Ignition problem? well maybe a carb problem? or is it something else? How to tell?

Ignition problem? well maybe a carb problem? or is it something else? How to tell?

Home
»
Keeping The Dream Alive!
»
Technical

http://209.208.111.198/Topic83672.aspx

Print Topic | Close Window

By Pete 55Tbird - 12 Years Ago

Peeeot

As much fun as it is to try and guess what might be wrong with your 57 Ford ( black) it is sort of like playing the game Battleship. One wild guess after another.

Can you hook up a compression tester and get some reading both dry and wet. POST the results.

Attach a manifold vacuum gage to the engine and leave it on while your car starts and then starts to have its problem(s) POST the results.

Leave a inductive timing light attached and test for regular spark pulse both before and after the problem happens. POST the results.

Throwing new parts at a car will work after some period of time but it will get expensive. Car engines are just air pumps. Put a combustibe gas in and provide a spark at the proper time then allow the spent gas to exhaust, then start the process again.

Give the forum some HARD DATA and you will get more than guesses. Pete

By peeeot - 12 Years Ago

Hi Pete!

I'm not sure what you mean by wet and dry compression, but the numbers taken hot after the problem showed up were as follows: 167,161,161,156,158,160,160,155

Manifold vacuum is upwards of 20". The needle is very steady until the misses show up. The needle will dip a couple points with each miss and bounce back basically in an instant. The vacuum drops off as the engine stops.

I will have to check the ignition signal cold again as I haven't in some time. When it is really acting up (hard to even get it to start up) there is far more "dead" time than flashing time shown by the timing light on the coil wire.

By aussiebill - 12 Years Ago

Pete 55Tbird (6/17/2013)

PETE, if you follow all the posts from #1 you can follow whats been checked at this point, i think there are a few other components that help the air pump run correctly.

By aussiebill - 12 Years Ago

peeeot (6/18/2013)

PEEOT, to me those comp figures are around 10% variation and fair for age of car. i cant help think the needle dip could be sticky or non seating valve to drop a couple of points, but still anything is possible. I,m assuming you have adjusted valves and checked for bent p/rod? Just my thoughts as i read on in your quest.

By aussiebill - 12 Years Ago

aussiebill (6/18/2013)

peeeot (6/18/2013)

The wet/dry comp test is retesting the cyls again but with a small squirt of oil in cyl you are testing, it basically restores compression at the rings and generally shows little difference if rings are good or greater difference in poorly sealing rings, i would be supprised if that is your problem. regards bill.

By peeeot - 12 Years Ago

Bill, I agree with you. I find no fault with the compression. I just did a valve adjustment about a week ago, and no pushrods are bent. It is extremely difficult to tell whether the fluctuations in the vacuum signal are responsive or causal. I believe they are responsive, as it is not at all surprising to me that there would be a dip in vacuum when an ignition miss occurs.

By Pete 55Tbird - 12 Years Ago

PETE, if you follow all the posts from #1 you can follow whats been checked at this point, i think there are a few other components that help the air pump run correctly.

AussieBill YYYY Forever Y Block YYYY

Bill, If this were 1970 in the US and peeeot drove his 57 Ford into any garage a guy who was very familiar with cars with points and carburetors would diagnose the problem and fix it. He could hook up his Sun machine, his occiliscope his timing light and his vacuum gauge. HE WAS THERE and he OBSERVED the symptoms.

This isn`t 1970 it is 2013 and the members of this forum are not where peeeots 57 Ford is and so we rely ,on the written description we get.

I find peeeots descriptions to be be vague confusing and not prescise, and or descriptive. This is probably a personal failing but since NO ONE else including YOU has any solution a BETTER, CLEARER, EXACT report on; 1 The manifold gauge reads X when first started and after warm up just prior to stalling reads Xa would tell me a lot. Like if the exhaust system has a mouse nest inside that is choking off the exhaust gas.

I agree with you that he has several components to replace ( engine ) ( car ) but that seems excessive to me. JMPO Pete

By oldcarmark - 12 Years Ago

If you read the Posts a suggestion I made early in the topic was to do a scope test with someoe who knows what they are doing and that should give a clearer picture of what is breaking down.I still think that would give an answer to this ongoing problem which I believe is ignition related.JMO!

By aussiebill - 12 Years Ago

Pete 55Tbird (6/19/2013)

PETE, if you follow all the posts from #1 you can follow whats been checked at this point, i think there are a few other components that help the air pump run correctly.

Yes, is difficult converting mechanical function to exact words and not being there, we are all only turning on our expeirence and having fun while we help, most of all peeoot, certainly gets my vote for dedication and perserverence. Actually that garage guy you describe was me , with automotive repair shop in mid 70,s till 1990, and specialising in all cars makes models mostly with carbs and points. I only just sold my SUN tune up machine! We await more reports.

By snowcone - 12 Years Ago

Don't often hear about "plugs n points" anymore.
I started my apprenticeship in 1972 and back in those days we didn't replace anything.
I had to clean spark plugs on the old Champion abrasive cleaner and then "refurbish" the contacts on the points with glasspaper.
An hours labour to save $10 in parts but that was how it was done then.
We had a timing light in the workshop but the old guys said they could do it better by "ear"
Times have changed a little.........

By peeeot - 12 Years Ago

Oldcarmark, I think you're quite right. I am going to try to locate a shop that has a scope (and maybe a tailpipe sniffer) with hopes they will reveal the key here. I have been avoiding shops because they are almost certain to redo everything I have done and charge me for it, IF they are even knowledgeable enough about the old stuff to get that far. EVERY interaction I've had with shops as a customer has been disappointing and frustrating.

Pete, I have been as specific as possible short of posting video as to the behavior of the gauges and engine. If I have been vague it is because the answer is vague. For example, the vacuum gauge needle at the point of stalling might go from about 3 seconds of perfect steady 21" to 0 in a matter of about a second. I cannot carefully describe what it does in that second, so I say it "drops off". There is no steady decline, no reliable, consistent behavior except that it will reliably stop running when I put it in gear or turn the lights on once it's hot. There is an intermittent, and I mean random, inconsistent, miss that will occur in the hot idling engine at about 700 rpm. If I back the idle speed screw off to decrease the idle further, the engine will slow to a stop much the same way it would if I had turned the idle speed below 450 rpm when the engine is still cold. I can tell that this problem is trying your patience much as it is mine, so please let me thank you again for trying to work through it with me. Please know also that I am posting in part as a sort of journal/means of thinking "aloud" as I try to work through this. The odds of a weird problem like this being solved without hands-on tinkering and observation are such that I can hardly expect a solution out of you guys, but it sure is helpful bouncing ideas around.

By lowrider - 12 Years Ago

Sounds like a valve problem to me. You mention when it starts to miss the vacuum gauge drops a couple points with each misfire. When it starts missing if you can pull plug wires one at a time while watching the vacuum gauge the cylinder that is missing wont change vacuum reading.

By oldcarmark - 12 Years Ago

If you can find a shop with a good scope and someone who knows how to read the results there is no reason for them to want to redo anything.All you are looking for is a diagnosis using the scope.I would hope that with the advanced equipment they have today it shouldn't take long to see the problem.They use these on todays "computers on wheels".The ignition system on cars 50+ years ago are simple compared to what they have now.

By peeeot - 12 Years Ago

lowrider, I am going to try that at the next available opportunity. If a valve or lifter is sticking, it must be doing it only partially and intermittently. It IS an item that could change with temperature and account for the behavior though, and I haven't tested for it specifically so I'll definitely have a go at it.

By peeeot - 12 Years Ago

Cautiously good news!

I began to do as Lowrider suggested and immediately noticed what I believe to be critical information. I started the engine with the vacuum gauge attached and looked at the perfectly steady 21" reading. Then, I pulled a spark plug wire and what I saw was a small drop in vacuum, maybe about 1", paired with a slight pulsing fluctuation in the needle. This is not at all what the needle looks like when I'm getting my hot engine miss. That miss is a much larger, hard drop of 3-4" which immediately springs back up. If I were dealing with a spark or mixture-related miss, it should look like it did when I pulled the plug wire. So obviously I have misinterpreted what the vacuum gauge was telling me.

Since my pushrods are not bent and compression is good, I believe what is happening is one or more of the lifters is binding up on its way DOWN from the open valve position, when the valve spring is pushing the rocker, pushrod, and lifter back against the cam lobe. I think it is only a partial bind, resulting in slow valve closing intermittently. I know that there was an issue with the exhaust valve rocker on cyl #1 delivering oil to the top of the pushrod. Perhaps that lifter has not been adequately oiled.

Any suggestions for how I could conclusively test this theory, or fix it? I am thinking warm the engine up, change the oil, add a quart of MMO, and run the hot engine with the MMO for a time and see if the miss goes away. I am also thinking I'll pull the valve covers and visually inspect the lifters for oil coverage or anything else that might be weird.

By aussiebill - 12 Years Ago

aussiebill (6/18/2013)

[quote]peeeot (6/18/2013)

Hi Pete!

Manifold vacuum is upwards of 20". The needle is very steady until the misses show up. The needle will dip a couple points with each miss and bounce back basically in an instant. The vacuum drops off as the engine stops.

PEEOT, to me those comp figures are around 10% variation and fair for age of car. i cant help think the needle dip could be sticky or non seating valve to drop a couple of points, but still anything is possible. I,m assuming you have adjusted valves and checked for bent p/rod? Just my thoughts as i read on in your quest.

With your latest observation being 3-4 point drop on vac guage generally indicating sticking valve when engine warms up, i would have a look at engine running without valve covers on, usually theres not that much oil idling, place a few rags on inlet side and other places, watch for rocker arm wobble or p/rod runout, also try rotating p/rods to see if free. you could also shine timing light on these one at a time to get clear look at them. I realise will be harder when gets hotter but miss may develop then and you may be able to pinpoint any differences? Could you have a worn rocker /shaft and binding r/arm, perhaps later when cool, remove assy and check shaft for wear, then see if you can wobble any valves. Again, this is only my view re the sympton you describe and thats what i would do to try and eliminate things before proceding further, Good luck ! Smile

By Y block Billy - 12 Years Ago

I recently had sort of a similar problem on a guys engine and it turned out the distributor vacuum was leaking very slightly so the timing would creep retarded until a small pop was heard, it was hard to tell the distributor was leaking. Also a defective condenser can cause a similar problem sometimes. A different distributor with petronics fixed the problem.

By aussiebill - 12 Years Ago

Y block Billy (6/23/2013)

Billy, i agree with that, have thought that would certainly be worth the effort, and you just cant beat Pertronix reliability. Sure is interesting post.

By Moz - 12 Years Ago

peeeot, also have you measured the voltage on the points side of the coil, I had a miss from mid range to top end once that I couldn't find, a low voltage on the points side will allow not enough charge in the condenser.

By peeeot - 12 Years Ago

Moz, the negative side of the coil shows 6.2V when the positive side shows 10V.

Billy, the vacuum advance is new and additionally I have been doing much of my testing with it disconnected.

I have made sure that I am not losing any timing when the car goes into idle or into gear. I have also done my best to determine exactly where on the crank damper TDC occurs, and as best I can tell, the damper markings are accurate within 2-4 degrees. I mention this because as I am working with the car right now it runs noticeably better at low speeds if I advance the timing to about 20 degrees initial. That makes no sense to me. It will quit right away if I retard the timing below 10 degrees.

I removed the driver side valve cover to look at the lifters and pushrods. They are definitely all oiling and spinning and not bent, with the exception of #1 exhaust, which is not oiling on the pushrod as mentioned. I moved the overflow outlet over so that the discharge of overflow oil falls directly onto the dry pushrod, but it didn't change anything about how the car ran. I did not remove the passenger side to look at it because I have looked at it before, not long ago at all, and it looked the same: rotating pushrods, plenty of oil everywhere, none bent. I am certain that has not changed.

Unfortunately I think I exaggerated the amount of a dip I was seeing in the vacuum reading. Certainly, it is larger and more pronounced than what occurred when I pulled a spark plug wire off, but I was really watching it today and the largest drop I ever saw was nearly 2", not 3-4. Most of the time when it would miss it would drop exactly 1". I pulled a wire again and the drop there with each miss was very small, maybe .25" of vacuum.

I took two videos of the vacuum gauge with the hot engine running. The first I took with the mixture screws out 1 turn. The second I took with the mixture screws out 0.5 turns. I would love for interested parties to take a look at these videos, as they show exactly what is happening, and how weird it is. I would be happy to email the videos; they are each under 800KB.

I was very hopeful that this was a valvetrain problem but it really doesn't look like it now that I'm testing for that.

By aussiebill - 12 Years Ago

Hmmm, 1 turn out with idle screws seems lean, have you tryed with screws out about 1 3/4 turns and reset idle speed and timing and see if miss occurs. Although i see you have tried with another carb. I,m starting to run out of suggestions.: Wink

By pegleg - 12 Years Ago

Pete, I know this has been asked (almost everything that would affect it, has been) but how are you sure the marks are correct? The comment about 20 degrees making it run better has me wondering. My own F code loves more initial advance, I have it set on 16 degrees but it would love more. Remember F codes are only around 8:1 though I can't see that making a lot of difference.

To me, it's beginning to sound as though the damper is wrong. The vacuum drop might be attributed to the vac advance retarding as the vacuum falls, which creates a further drop in revs, which creates lees vacuum etc, etc ad infinitum. I know that does not help with the vacuum disconnected, but it's the best I have right now.

By peeeot - 12 Years Ago

Aussiebill, the factory data sheet calls for 1 turn initial setting and a final setting range of 1/5 to 1 1/2 turns. It's funny because the carb that was on the car when I bought it would not run in that range, requiring at least 2 turns to run at all, whereas the current carb slows down noticeably with anything more than .5 turns, as long as the main fuel circuit is not in play. I even tried swapping the primary booster assemblies from carb to carb to see if that was where the difference was, but it didn't really change anything.

Pegleg, to check the timing marks what I did was to remove spark plug #1 and stick a screwdriver in the hole with my fingers against the head holding the shaft of the screwdriver. I slowly turned the engine with a wrench and socket with my other hand and tried to get a feel for where the piston stopped moving upward and where it started to go back down again, knowing that TDC would be in between. It is not the most precise way in the world but when I would think to myself "this should be top" I would look at the pointer and it would be very close to the TDC mark, within a few degrees. I tried it a few times consecutively and the result was consistent.

I am very discouraged. There have been so many times that I thought "aha! A new angle that hasn't been considered yet. Surely this will reveal the problem!" only to end the day with the car unable to move under its own power yet again. I just don't understand how so many changes, adjustments, replacements, and experiments can fail to yield any conclusive sense of what is wrong. I have been thinking about it so long that I don't even know how to get a clean slate in my mind or a fresh perspective on how this problem could still exist. Those vacuum gauge videos are about the only thing I can think of that one of you might look at and be able to see something right away that I'm not recognizing.

By MoonShadow - 12 Years Ago

Some times the best thing to do is step back for a while. The approach it as a new problem with a fresh mind. We can get so wrapped up in what we have done that we miss simple things.

I did a tune on on an Olds years ago. The regular points, plugs, condensor, cap and wires job. When I went to start it to set the dwell and timing the engine would not start. I went over everything I had touched probably 20 times each. Reset, re gapped, etc. etc.. After a couple of hours my buddy walked in and I told him the monster delima I was having. He took a quick look and said "did you check the coil"? Of course I hadn't, put a used coil on and started it right up. The symptoms were all there but I was so focused on what I had changed on the car I couldn't see it.

Anyway, thats my story for stepping back a bit. Hope this helps. Leave it for a while, come back fresh, and start the troubleshooting again. Good luck. Chuck

By Moz - 12 Years Ago

6.2v is fine, I was just curious as I also have a Mazda rx3 that has a rough idle & misfires from 6000 to 8000rpm. With its twin ignitions it does make diagnostics more difficult, but on testing the coils I found one of them was only at 4v on the points side, the spark plugs that are run by that coil kept fouling as well, although I haven't changed the coil yet to see if that fixes it or not I have also noticed when I turn my headlights on the idle drops about 100rpm & that's with the regulator set at 14v.

By Moz - 12 Years Ago

hey chuck I forgot to put the wire on the points on a customers car once when tunning it pulled my hair out for hours, I didn't notice it because it was sitting next to the points & not touching them, I only found it when I decided the points must be faulty & went to pull them out.

By Moz - 12 Years Ago

another thought I agree with bill I would have the mixture screws out a little further than one turn, I know the factory data sheet says that but they can be wrong most carbys like between 1.5 -2 turns out from seated, all carbys are different so I take no notice of the factory data as that is done by engineers in the factory & not under outside influences. the autolite on my 272 has a sweet spot at 2 turns out, in your case at the moment I would screw them in to seated then screw them out slowly until it sounds right & don't worry about the turns out for now. if they run better at 2 turns or even 2.5 then leave them at that for now, remember its only idle mixture, re adjust the idle speed & then that's 2 things to remove from the list.

By OldTGuy - 12 Years Ago

Peeot,

From your vacuum gauge readings, it looks like you have a sticking valve in a valve guide. I would suggest you add a couple of ounces of MMO to your gas tank, this should help. As far as your carburetor adjustment, set the idle screws with the vacuum gauge also. Adjust to get the highest vacuum reading and smooth idle, disregard the amount of turns out on the screws as per the manual. The gas we get today is going to run different than the gas availible in 1957. Since your vacuum reading is 21" at idle, your engine should be real close to be in tune. I hope this helps.

JJ

By peeeot - 12 Years Ago

All right guys, I believe I have finally seen what I needed to see to completely be on board with all of you who have pointed to a sticking valve.

I drove the car around and warmed it up and let it idle in neutral, then went out back with a clean paper towel and held it about an inch behind each pipe. Sure enough, right before each miss/spit, the paper towel would suck into the pipe. I wish I had thought to try that a long time ago, as it was very obvious.

Question now is, what do I do about it? I have just added some MMO to the gas and crankcase. If that gets me nowhere, I'm guessing nothing short of removing the heads and having them rebuilt will get me anywhere? Any suggestions?

By GREENBIRD56 - 12 Years Ago

Just thinking out loud - when I adjust the valves on the bird, I use a gloved finger on them one at a time to single out one on the verge of clicking or not. would that help isolate the culprit here?

By aussiebill - 12 Years Ago

GREENBIRD56 (6/28/2013)

Just thinking out loud - when I adjust the valves on the bird, I use a gloved finger on them one at a time to single out one on the verge of clicking or not. would that help isolate the culprit here?

Steve, i agree and glad to see we have narrowed it down to one thing to persue at this time, Peeoot, i would try resetting the valves with engine running, first loosen lock nuts if that style of rocker, then bend feeler guage, makes it more accessable past exhaust, just slip feeler in and note any rpm changes, and loosen or tighten rocker, my lingering thought earlier was worn rocker tip giving wrong setting and once warmed up may tighten valve clearance,be on lookout for that misss as it warms up and you may be able to localise it. i know its just a thought and we await your pleasure. Smile

By oldcarmark - 12 Years Ago

If you are trying to isolate the problem cylinder would removing one spark plug wire at a time and run the engine not tell you which cylinder is the problem?I seem to recall reading the instructions on the Vacuum gauge and there was something along those lines when trying to locate a cylinder causing vacuum to drop.If the plug is not firing you would not get the reaction at the tail pipe.Does this suggestion make sense?

By peeeot - 12 Years Ago

Greenbird, what exactly do you do with your gloved finger, and how can you tell whether it's on the verge of clicking? I do not have excessive valvetrain noise.

aussiebill, are you saying you leave the feeler gauge in between the valve and rocker with the engine running? Wouldn't that deform the gauge? I have always wondered how people check clearance on a running motor.

oldcarmark, I'm not sure whether that would help or not. If the paper towel sucks into the exhaust right before the miss, it would suggest an exhaust valve hanging open temporarily during some or all of the intake stroke. That way, the intake draws in some inert exhaust gas, weakening the charge strength to that cylinder. As the compression stroke begins, the sticky valve is forced shut, giving good compression numbers, and the weak charge is burned. It completely accounts for the symptoms. So as long as the valve is still sticking, even with the plug wire disconnected I should see the temporary suction at the pipe end created during the intake stroke.

There are at least 2 exhaust valves sticking because the dual exhaust pipes are separate and I get misses out of both of them at different times (not simultaneous).

Do you think if I can isolate the offending valves, I might be able to resolve the issue without pulling the head? If so, my next task will be to find the trouble! May be able to see it with the timing light, because if the cylinder is too lean it might not fire at all.

By MoonShadow - 12 Years Ago

Try this link.

http://www.y-blocksforever.com/tech/html/valvelash.html

It was written by one of our members that is no longer with us. The directions are simple and it takes the wear out of the equasion. Chuck

By GREENBIRD56 - 12 Years Ago

I'm thinking that the sticky valve can be felt with your finger on the rocker tip - the clearane gap will go excessive and a touch will silence it.

By aussiebill - 12 Years Ago

[quote]peeeot (6/29/2013)

By Hoosier Hurricane - 12 Years Ago

Peeot:

You mentioned a couple pages back you would look for a shop with a scope. Did you find one? If so, the scope would likely be equipped with a cylinder leakdown tester. With that tester, properly used, they can evaluate each valve in each cylinder for proper sealing. They can also check the rings and for leakage into the cooling system. If they find a bad valve, there will be no fix except to pull the head(s) and grind the valves.

By peeeot - 12 Years Ago

Hoosier, I have not yet located a shop equipped to scope my ignition system. That doesn't mean there isn't one within reach, there just aren't many places that work with the old stuff anymore.

Moonshadow, those instructions are the ones I followed to set the valves most recently.

Just an observation, if I pull a spark plug wire, I get a steady miss out of that cylinder's exhaust pipe, and if I hold my paper towel at that pipe it sucks in steady with every miss. I thought that the paper towel sucking in was a definite indicator of sticking valves, but if that's the case, then why does a KNOWN, intentionally caused ignition miss cause the same result (sucking in at the tailpipe)? Also, if the valves are sticking, why does bypassing the resistor eliminate all misfiring?

By peeeot - 12 Years Ago

Here is the latest update.

First, still trying to find a shop that might be able to solve this. I found one with a scope nearby but they are not experienced with old car technology.

Second, have redone some old tests and tried some new things, each time recording what I did and what affect it had. Here they are, not exactly in the order performed:

SYMPTOMS: hot engine develops intermittent random sputter/misfire below approx 750 rpm. Hot engine stalls immediately when shifted into gear. Hot engine will not remain running below 650 rpm for an extended period of time in any gear.

1. Installed Edelbrock 1405 carburetor. Regardless of how I adjusted it, I was unable to produce any improvement on the symptoms.

2. Tested for vacuum leaks. I tried creating a vacuum leak at the vacuum pump, which increased the engine speed, and I tried hand-choking the engine, which slowed the engine down. In the past, soaking the intake and lower carb with water did not affect engine running.

3. Checked coil current draw. 4.0A engine stopped, 2.7A engine running about 700rpm. Rechecked current draw on cold engine, engine stopped, no change. Specs are 4.5 and 2.5, stopped and at idle, so I see no problems there.

4. Increased dwell angle from 26 to 29, no change in symptoms.

5. Checked voltage to coil with analog meter and confirmed coil always sees at least 9 volts, even during trouble symptoms.

6. Checked resistance from starter relay to resistor; was negligible.

7. Advanced timing as far as 22 degrees initial, vacuum advance plugged. Engine ran faster and better with all of that advance but ultimately symptoms persisted. Retarding timing below 10 degrees exacerbated all symptoms.

8. Checked for accuracy of damper markings by hand-turning engine with my pinky against the cylinder wall and top of piston. Marks accurate within 2-4 degrees.

9. Repeated hot compression test, numbers all within 2 psi of last time I ran the test, most exactly the same. Worst cyl 155, highest at 167, rest 160-162.

10. Ran with battery charger attached, no improvement

11. Ran with gas cap off, no improvement

12. Ran with 0.6 ohm resistor installed, no improvement

13. Ran engine with valve covers off, feeling each rocker arm and then each spring cap looking for signs of a sticking valve. Nothing felt at all out of the ordinary. No unusual noises, or more pronounced clicking, or "double seating" of valves (by which I mean, once the valve came back up it didn't move anymore, and the motion from closed to open to closed was smooth and regular on every valve)

14. Listened with hose at tailpipes and intake as engine was spun with ignition disabled and throttle open for evidence of valve irregularity. I wasn't sure that I heard anything unusual.

15. Held paper up to tailpipes as disabled engine was spun over; there was some sucking in but I am not sure whether that means anything

16. Checked manifold vacuum as hot engine was spun over; reading fluctuated between 4-4.5". Was not rock steady.

17. Loosened all valve screws a small amount twice; based on calculations, probably opened them all up 2 thousandths or more. They got noisier but engine running was not improved.

18. Watched timing light with pickup coil on coil to distributor ignition wire. Ignition signal was 99% perfect. Tried retarding timing, leaning mixture, putting car in gear, stalling the car by each method a few times while watching the timing light, and the signal was strong to the finish every single time.

19. Verified the presence of fuel in the carburetor bowls at time of trouble.

As I understand it, to run an engine needs compression, fuel and air in the right mixture, and a spark at the right time. I have done everything I can conceive of to confirm the presence of all of these elements. In my experience, vehicles which have tested worse in every category have been able to succeed where this one fails.

If I am unable to find a shop or get this resolved for a reasonable cost, I will abandon this drivetrain, if not the whole project. What a bummer.

By slick56 - 12 Years Ago

Is the exhaust butterfly valve (if still fitted) opening?

Have you tried a different intake? A crack into the exhaust crossover passage could cause problems.

Man, I think I would have given up by now...

By ian57tbird - 12 Years Ago

I feel for you. Have you checked plug lead impedance? If a lead or leads are marginal they can break down with temp change. A trick I learnt, Try a carb starter spray when looking for air leaks instead of water. It's very effective, but just remember it's flammable.

By PWH42 - 12 Years Ago

With that much compression and that little vacuum,you've got valves open when they shouldn't be,or you have a substantial vacuum leak.I'm betting you have a timing chain that's jumped a couple of teeth.I don't know why it gets so much worse when warm.

By aussiebill - 12 Years Ago

slick56 (7/13/2013)

Slick, i have come across that cracked floor in intakes over the years and generally gives backfire result , but changing intakes could be worth a try, as its the one thing that hasnt been changed?

By peeeot - 12 Years Ago

PWH42, just to be clear, that low vacuum reading was the number when the engine was being spun by the starter with the ignition disabled. When it is actually running the number is 19-21" depending on mixture, timing, etc.

ian57, all the wires are new, and it's true I haven't gone back through them and measured resistance since installation. I have avoided using carb spray because I didn't want to ruin the paint on the intake but I suppose at this point having to repaint it is worth getting that confirmation. I would think that if I were dealing with a vacuum leak that intentionally creating one as I have done would make all the symptoms worse, but it didn't seem to do that. I tried creating a vacuum leak on my other old car to see how it behaved and it did not cause the same trouble. Perhaps it would be worth running the valvetrain-related tests on the other car for a comparison.

Slick, the butterfly has been removed. I have checked for a leak in the manifold as best I knew how, both visually and plugging one pipe while blowing air into the other and listening at the intake, but there was no evidence of leakage. Who knows, though, maybe it cooled down enough to close in the time it took me to get that test together.

I have a couple questions you guys might be able to answer that would help out, all based on assumptions I'm making that I'm not totally certain are valid.

1. I assume that if I see a steady flash from my timing light at the coil to distributor wire, that means that a spark is jumping the gap at each spark plug consistently OR ELSE leaking out of a plug wire to ground consistently. In other words, I can take such a steady signal at that wire to indicate that my ignition system is reliably generating and distributing a spark and therefore any misfiring that occurs while I see a steady signal must be caused by a mechanical or fuel-related issue. Is that a valid assumption?

2. I assume that consistently getting the compression numbers I'm getting means that, at least while conducting the test, the valves ARE fully seating. Is that a valid assumption?

3. I assume that in the course of trying 2 different '57 AFBs with bone-stock correct calibration and 1 modern, quasi-universal, never-been-used-new carburetor, and adjusting float levels and mixture settings and checking passages and replacing gaskets in each, that if I was dealing with a carburetor problem here I should've been able to resolve it by now. Do you think it's fair to rule out carburetion?

If we agree that all signs point to properly functioning fuel and ignition systems, then mechanical is the only alternative. I've tried what I know to actually FIND a problem in the valvetrain without getting a conclusive result one way or the other. I could remove the intake and test it for cracks. I could also remove the heads and go through the valvetrain, have them rebuilt, whatever. My goal has been to find concrete evidence that there is a problem in either area before digging in, but as has been the case with this whole problem, I haven't seen enough to make me sure.

What would you do at this point if a full teardown and rebuild was not an option?

By ian57tbird - 12 Years Ago

I wouldn't rule out ignition yet. Coils can give intermittent faults that will kill an engine, earthing internally when warmed up then appearing perfect a short time later as they cool slightly. Not sure what you would see with timing light direct from coil being 8x that of a plug lead. The light might not dull fast enough and for that matter the brain might not be able to register it.

By Pete 55Tbird - 12 Years Ago

peeeot

It could be that the 9 volts that your coil sees with the engine running is TOO MUCH and the coil is overheating. Try another ballast resistor and get the running coil voltage below 6.9 volts ( Fords 1966 car limit ) and see what that does. Pete

By ian57tbird - 12 Years Ago

From my understanding coils aren't specific to a particular impedance resistor. I recently purchased one and tried to match it to the resistor for my car but they all just specified, (use with resistor). If the coil is the problem then it would be faulty and it would be unlikely that changing the resistor would fix it. If the coil is designed for a lower voltage and is now breaking down then it still has something wrong with it now.

By pegleg - 12 Years Ago

ian, Go back and read the entire post from the beginning. He's tried 3 or 4 coils and almost the entire ignition system.

By ian57tbird - 12 Years Ago

Sorry, might of missed it. I did read all that is there quickly and the piece written on latest update by peeeot. Could see the testing of voltages but not swapping out of coils. When I go back to page 1 the subject seems to have already started. I don't see the subject from the beginning for some reason, maybe it was in there.

By ian57tbird - 12 Years Ago

I didn't read anything on road test. Has it been driven? If so is it doing anything unusual?

By slick56 - 12 Years Ago

The post was originally More ignition problems. , posted on April 16th. I don't know how it evolved into this one. The first post in the original thread describes Peeeot's "first lengthy drive in warmer weather". I would post a link to the original thread, but i don't know how...

By peeeot - 12 Years Ago

http://forums.y-blocksforever.com/Topic81719.aspx is the original topic. Pete 55Tbird started this one, I think with a mind to getting a fresh start on the subject. Rather than posting in two topics I just let this one take over, but when I have resolution I will update the original topic and link to this one as well.

My recent post with the 19 things I tried recently starts off with a list of a few symptoms. The only other thing the car is doing is stumbling under sudden throttle, but that is caused by the accelerator pump, which is hanging up in the bore in the carb body. I need to polish the bore thoroughly.

I was thinking about it while working on another car today, and in addition to the things from my last post, I'm also wondering: if I had valves sticking open, even temporarily, wouldn't I be getting backfiring through the carb or out the tailpipe? Because I am never getting either.

By ian57tbird - 12 Years Ago

Found the old post. Did not realize it has been going for 3 months. DEPRESSING.

Spent a few hours reading through it all and I might mention a couple things.

The symptoms sound so much like it is running out of fuel but you sound absolutely sure there is still fuel up there when it dies.

It is normal for voltage to drop at idle when you load up the system by turning on lights and other things. The gen can't produce enough at low speed and it is not uncommon to even see it go below 12v. Spinning the gen faster would fix it but then it would destroy itself at higher revs because of the windings on the armature. Alternators can be spun faster but will still drop of a bit at idle. Nothing to worry about and the car should run OK if everything else is good.

Your charge voltage is very high which will bring the battery up to full charge quicker but is also over charging it and will be putting all of the car electrics under extra load as well, and may shorten the life of globes, fuses and alike. When I was studying auto electrics in my earlier day, we were taught that the ideal voltage to set the regulator at was 13.8v to 14.2v. My FJ62 Landcruiser runs at about 13.8v and I seem to get an unusually long life out of batteries which I suspect might be to do with the lower end charge voltage.

It is normal to have a small amount of resistance in the wiring to the resistor through the ignition.

You said you can't test condenser but you can test them for leakage with an ohm meter.

You have been quoting higher than stock idle speeds so does it have a bigger cam and if so what idle speed is expected with it?

Something that wasn't mentioned was if you checked wire from coil to dizzy where it connects through the distributor and on the other side to the points. Is there any chance the insulating washers are compromised and it could be getting a partial short to ground on the distributor housing, maybe with temp change. Check this by opening you points, disconnect wire from coil and check with ohm meter to ground, just on distributor is good. I would also disassemble where it enters dizzy housing and check that all washers are good.

Slightly higher voltage to the coil should not bother it unless it is already on its way out. To give you an example, I had an intermittent problem with my car cutting out while I was driving and running rough when it came back to idle which I thought was the coil as it would come good if the car sat for ten minutes and then restarted. I went looking for the resistor and after discovering there was none I bought a new coil as well as a resistor. It wasn't the problem and the coil was fine but it had been running for a couple of years that I had the car and I'm not sure how long like that with the previous owner. That coil was running at about 14v most of the time and did not give up, (though not recommended). My coil sits on the manifold as well and the heat is no problem.

While grasping at straws here, something that can happen on the ignition side of things but I think is unlikely as you said you changed the leads, is cross firing but not just through bad insulation but also induction. When wires are run parallel to each other for a long distance a voltage can be induced in the other wire similar to what happens in the coil. Crossing wires over should eliminate that.

Good luck.

By peeeot - 12 Years Ago

Tell me about it! Thanks for taking the time to read the whole saga and offer advice.

Yes, I am quite sure that there is plenty of fuel in the bowls when the trouble symptoms show up and the engine dies. The early AFB has a pair of sight plugs, and I have been able to verify that fuel is in there at the same level from cold to hot & stalled.

With regard to charging voltage, the regulator is temperature-compensating and in the summer weather the typical charging voltage is about 14.5, which is pretty reasonable I think. I tried dialing the voltage back a month or so ago and it didn't help anything. What's more, the manual specs voltages approaching 16 in cold weather. I called a local specialty shop that rebuilds generators and talked with them about the charging system for a while. Between the manual's info, my testing and experimentation, and that conversation with the generator shop, I feel confident that the charging system is functioning satisfactorily and not a cause of my hot running problem.

I don't think I have tested my condenser for leakage, but I have installed 4 brand new ones with no change in symptoms, so that's another item I've ruled out.

The cam is stock, in fact I believe it to be original from 1957. I have been talking about idle speeds of 650-800 rpm because once the thermostat cycles about 3 times I have been unable to get the engine to stay running below that general speed range. The last time I worked on the car, I advanced the distributor to about 22* initial, and only then was I able to achieve hot engine idle at speeds of around 500 or lower. Even then, I still have intermittent misses, stalling in gear, and hard starting (the last symptom to show up).

I may not have mentioned it, but I did check the coil to distributor primary wire for continuity, voltage drop, and short to ground. I have watched the voltage at the negative terminal of the coil with an analog voltmeter on several occasions. It is stable with a slight, regular vibration of the needle, around 6 volts as I recall. I am not sure that I have watched that voltage through the point of stalling though.

If I have crossfiring, wouldn't I be getting backfire or afterfire? And if the ignition were at fault, wouldn't I be seeing interruptions in the signal at the coil wire with my timing light?

Isn't it strange that the engine acts better and not worse with 22* of initial advance? That bothers me.

Could some fault of the transmission or torque converter cause any of these symptoms, ya think?

By stuey - 12 Years Ago

hi Peeeot

just been reading thro 11 pages 1st thread and 6 pages of the new. you have changed out just about every thing except the distributor. you have changed points capacitors and checked wiring.what sort of distributor do you have? 1957 is it one of those with a disc plate thingy with hundreds of ball bearings and the weights concealed below?

i had probs with one of those, not quite the same symptoms but similar turned out to be the weights stuck. i was real put of looking for the trouble because the first time i lifted the dist. i dropped the oil pump drive into the sump pan and the site of all those balls i had visions of them all over the garage floor. so i got a later model and swapped it out. not too dear. just a thought i you have access to a spare dist.

keep up the fight

stuey

By peeeot - 12 Years Ago

Stuey, yes, I have the original style rotating-plate ball-bearing distributor. In an older post, not long after I got the car running, I had problems with stalling in gear. The problem went away (for the time) when I removed the distributor and completely cleaned and lubricated every part of it. I have not even driven 1000 miles since then. At the time, I was losing timing when I shifted into gear, but even then I was only retarding to 6*. I have made sure that the mechanical parts of the distributor are still clean and moving freely. I also made sure the oil pump shaft retainer was installed properly when I had the engine apart, so thankfully, it has not fallen into the pan!!

By ian57tbird - 12 Years Ago

You may think this is a stupid question. Just checking your terminology. Are you disconnecting the vacuum advance and plugging the carb when it is at 22 degrees advance?

By peeeot - 12 Years Ago

Yes indeed! I would have guessed that that much initial would make things worse at idle, not better. I was playing with an MG midget just yesterday which had a clear timing "peak" which, if advanced or retarded from the peak, would result in a decrease of rpms. But I can offer no explanation for why 22 degrees would be OK on my engine. It must mean that the mixture is burning really slowly. Maybe I should try regular gas instead of premium? But I run stock timing with premium on my Chrysler and there's no issue there.

By GREENBIRD56 - 12 Years Ago

Peeeot -One of our members - "oldcarmark" - once had a problem that I was reminded of as I read the various symptoms of your outfit. Initially, it wouldn't shift from park to drive without staggering and stalling ('56 sedan with 390 cfm Holley installed). The problem didn't turn out to be singular - it was many - and the sum result was an engine tune that didn't produce enough idle torque at low rpm. He could speed it up (to raise the idle torque) - and it would then slam into gear and stay running - no good, not a solution. He was very frustrated trying to get a handle on this - too many variables. On yours, it would seem the addition of heat decreases the idle torque further and makes the problem get worse - another variable.

His outfit had:

(1) Unsuitable spark advance - initial, increase rate, and total mechanical.

(2) Vacuum leak (excessive PCV passage in that case).

(3) Carburetor idle set-up incorrect (for his new Holley).

When a "tuner" takes on an engine/vehicle combo and works it up for a customer - they can take a "ho-hum" carbureted engine and literally make a whole different animal out of it. Most start by getting the ignition in order and going on from that. From the depth of investigation so far - you must have some useful components in hand - coil, condenser, cap, wires etc. I think you can do this tune-up yourself - just start with the distributor and go from there. For pros it is nearly always step one as the spark advance will dictate the carb tuning.

So what is the maximum mechanical advance in your distributor? - I'm assuming the flyweights are in good working order. If you "power time" the engine - determine the maximum mechanical advance by raising rpm until it stops - what is it? These Y blocks without special or reworked cylinder heads like a 36º maximum when there is no vacuum advance connected. If you set the timing at 36º (elevated rpm necessary) and allow it to return to idle - how far does the spark advance drop? This might require placing an auxiliary upper mark on the damper by measurement from the current "0".

Factory set-ups of the era had initial settings at idle of 6º and such. The engines actually produce better idle vacuum (and still start nicely) when that initial number is 10º and higher. Some of our clan are running as much as 14º+ initial with the Ford "timed" vacuum ports in use. In any case - the combination of your chosen initial and mechanical (only) should add up to no more than 36º. You will find that the engines run a bit cooler at idle when the timing is advanced as discussed here - the 6º is a bit retarded and builds water temperature from wasted heat. To get the distributor to operate in the desired advance range - from the initial you choose up to 36º - will take some alteration of stops in the flyweight mechanism. We can help you with this - the mechanical advance tuning is exclusive of the vacuum so that must be inactive.

The engine speed at which the advance can be "all in" - the rate of advance without "knocking"- is tied to compression ratio and gas quality. Swapping springs in the flyweight mechanism makes this happen. To be conservative, try to make the 36º be all in at 3000 rpm or there abouts. Getting the early spark curve correct can add many foot-pounds of torque to your engine - its worth the repetitive teardowns (if you don't know a guy with an old Sun machine). Ask Mark about this operation - he can probably field strip his distributor faster than I can explain the steps. You can get a variety of advance springs from various sources - Mr. Gasket #925D will get you a few choices.

Test the vacuum pot on the distributor to see how much advance it provides. With the engine running a fixed "high idle" speed and stable vacuum - apply manifold vacuum to the distributor and see how much it alters the spark advance. I've done this before with a long piece of tubing and another (high vacuum) "donor" vehicle running alongside. There are other ways to get the vacuum source - just try and be cognizant of the available change when it comes into play. A lot of the pots are adjustable if the upper end turns out too high when the vacuum advance sums with the full mechanical.

Next go to the carb and make sure it is in good condition to take tuning - float level correct - fuel pressure normal. Rule out every possible source of vacuum leak - my own experience has included poor fitting manifold gaskets, worn throttle shaft bushings and passing excessive air through the PCV. If you have PCV installed, a quick change is to simply plug the hose and shut it off at both ends, carb and manifold both. I used a 'Standard" '64 292 truck PCV on my outfit and it would literally run on the PCV air alone (throttle closed) - not good - had to orifice the hose to make the carb work correctly. It has to provide just a small amount of fuel to mix the PCV air - if the requirement goes too high, the mixture screws won't work in the proper range. If your engine doesn't have a PCV fitted it won't face this problem and you must look elsewhere.

This can go on and on - but the advice is to get the various "systems" functional and answering adjustment - and then optimize the next and so on. You will eventually reach the point where the engine produces the necessary torque to run at low rpm hot idle, in gear.

By Jerome - 12 Years Ago

If I remember correctly, when I went to rebuild my 57 distributor, I found the ball bearing advance plate had wore a memory pattern in the bearing race that biased where the advance plate came to rest under vacuum advance and distorted the point gap as well. I got lucky on CL and found a NOS vacuum advance ball bearing plate. I also discovered nearly all the ground wire strands (wire from the points plate to the distributor case) were severed from flex fatigue and ended up replacing it with a new small braided ground strap that would not bias vacuum advance.

Jerome

By ian57tbird - 12 Years Ago

As mentioned it could be a combination of problems compounding. I would at this point start swapping parts out with known good ones if possible (carb, distributor) and if that did not fix it then start to look at other things but at least you will have eliminated then as the problem.

By peeeot - 12 Years Ago

Greenbird, thanks for your thorough and informative post. I have always intended to test and tune the advance curve. I have been waiting to sort this issue out to try it. I have assumed that the curve is not critical to hot idle issues because it is a static value (initial only) at that engine speed. I have checked and confirmed that it is indeed static at low RPM many times. A cursory study with vacuum advance disconnected shows that advance begins around 700 crank RPM and hits the second spring probably around 1800 rpm and 10* of additional advance. It looked like it maxed out around 20* of advance on top of the initial. Perhaps not optimised, but nothing highly irregular.

I was away on vacation for a week and am back to take another look at things. I decided to ignore the idle/miss/die in gear and take care of the stumble I have mentioned. I have always thought it was the accelerator pump. At first, I had an old pump in there. Then, the new one was binding in the bore. I examined the bore more closely and it had some "texture" so I attempted to polish it with my dremel tool until the new pump was moving smoothly. I put a little oil on it and installed; it wasn't binding at first but as soon as it had soaked in the gas long enough it was binding again. I removed it and put the old one back in, and ever since I have had a nice consistent pair of streams of fuel from the pump. It appears, to my eye, to be as sensitive as it ought and delivering an acceptable volume. The stumbling, however, remains. I tried all three pump rod positions, no change. I tried choking the engine manually AND maximum pump volume and still no change. To open the throttle suddenly FROM IDLE SPEED is to stall the engine. I tried completely disconnecting the pump and there was still no change in behavior.

I noticed that the main boosters are beginning to discharge at about 1500 rpm, when there is still at least 1/4 of the idle transfer slot exposed above the throttle plate. Even with the accel pump disconnected, before the engine stalls when I snap the throttle there is some discharge from the boosters. Combined with the fact that my mixture screws prefer to barely be open, I concluded that I was probably dealing with a RICH bog and not a lean one, so the float setting, though set to spec, must be too high. I lowered it 1/32" and repeated the tests with no change to ANY aspect of performance.

By the end of all of this the engine had reached that stage in its troubles where it became difficult to start. I set up my good timing light and saw a perfect spark signal as the engine spun over but wouldn't start. To start the engine, I had to treat it like it was flooded, even though there was not any fuel leaking in (above the throttle plates, at least).

After lunch, I intend to go out and continue to lower the float incrementally until I notice some kind of change. Will post back then.

By peeeot - 12 Years Ago

I dropped the float as low as 5/16", double the specification. I didn't notice any difference until I dropped it that low. It became very difficult to start. When I got it started, the boosters did not flow at 1500 rpm, but had started flowing by 1800 rpm. I had to open the mixture screws up to 1.5 turns to get it to start, but once it started, it wanted them back at the usual spot of about 0.5 turns. Other than these things, every other aspect of performance was unchanged. Smooth, steady, miss-free running on the lowest step of the fast idle cam; missing and soon stalling at hot idle. Timing set to about 11* initial. Misses on the vacuum gauge involve a drop of about 0.5" Hg each. Timing light shows spark present always. Sudden throttle motion causes a stall. Blah blah blah.

At least it's consistent.

By peeeot - 12 Years Ago

I marked a piece of tape with timing marks at 5* intervals up to 50* BTDC. With the engine thoroughly hot, it would go into gear without stalling immediately ONLY IF the timing was 27* or more. With that much advance, the stumbling problem also vanished.

Why could it possibly require so much advance?

By GREENBIRD56 - 12 Years Ago

Old question - you're sure of the TDC location you are basing this on? Just checking....... 27º seems like a lot to me too.

The Y-block stocker cylinder heads typically need some early low rpm advance to work well. I use 17º (10º initial plus 7º of live manifold vacuum advance) to get the best idle vacuum on my outfit. Stock "C" heads, factory cam and tuned for this arrangement. Several have told me they use 14º initial and ported vacuum to the distributor. Anyway, half of the 27º and a little bit more wouldn't be unusual.

By aussiebill - 12 Years Ago

peeeot (8/4/2013)

I,m with steve, obviousley that much initial advance is not usual amount and we know how thorough you are, I think the TDC mark may need rechecking then see if the distributer is not a tooth out, but glad to see some of our initial suggestions re advance settings have made some improvement as we were all starting to doubt our own knowledge. looking forward to your findings. regards bill.

By oldcarmark - 12 Years Ago

Have you considered setting the timing using a vacuum gauge like the oldtime machanics did?It would be interesting to see where the timing ends up if you did it using a vacuum gauge as compared to where it is with the timing light showing 27 adavance.

By peeeot - 12 Years Ago

Indeed, I have checked TDC and the crank marks more than once and am confident that they are accurate within 2-4 degrees. I remember checking for it when I had the heads off too, when it's easiest to see.

I watched the timing and revved the engine up a bit before attempting a test drive. According to the marks, I was hitting the mid- to upper-thirties on the 1st spring alone, then continuing to accelerate the engine pushed the timing into the forties. The engine didn't seem to mind it, so I left the vacuum advance disconnected and took a spin. It was very nice to have a responsive throttle again. I could mash the throttle at any time and get a rush of power. If I pushed it hard enough, I did at times detect some spark knock, so needless to say I wasn't too rough with it. I did some stop-and-go and also some highway cruising at 3k rpm, everything felt fine and the engine was definitely running closer to the middle of the temp gauge (that is to say, running cooler) than it had last time I took it on the highway. I picked a route that avoided stops and two-footed it when I had to sit. When I got back to the driveway, I took my foot off the gas and the engine died pretty much immediately. It then started right back up in neutral, but stalled as soon as I put it in gear.

So, whatever it is that's going on, there comes a point when even all of that extra timing doesn't help. I tried advancing farther, retarding, enriching, leaning, idling up, idling down in too many combinations to mention through the course of today's tinkering but ultimately it was clear that no matter what I did it would not start behaving like a proper engine.

Wanted to mention that I temp-probed both the Chrysler and the Ford in several key places (exhaust crossover under carb, carb itself near mixture screws, exhaust manifolds, exhaust pipe before and after muffler). I wanted to be sure it was worth my while to remove the mufflers to see whether they were over-restricting the exhaust, which I have thought to be unlikely. Both engines showed very similar temperatures. Most important to me was the carb temp; the Ford was 105 while the Chrysler was 100. Both showed a temp drop of 20-30* from one end of the muffler to the other. I was not seeing any reason to assume trouble with exhaust flow so I did not remove them.

I'm ready to throw in the towel. I see two options to get this engine running: take it to a pro shop and pay them who knows what it might cost to let them figure out what's wrong with it, or else pull the engine and fully overhaul it. I just want to KNOW what it is. Can you imagine how terrible it would be to install a freshly overhauled engine and be right back where I am now?

By ian57tbird - 12 Years Ago

Just having a guess and not sure what it would do, but it sounds like you may have covered everything else. Could cam timing be out, and making it run like s__t

By Pete 55Tbird - 12 Years Ago

It might help to understand what is going on if you can give more specific information. I have nerver seen an engine that had the same manifold vacuum reading if the RPM was constant but the ignition timing was changed. If I understand your other posts the manifold vacuum on your car is 20 inches and rock steady until just before it dies.

Can you put a manifold gage on AND a tach AND a timing light and take a series of reading starting from a cold engine and then advancing the timing in stages until you have the 27 degrees that you find works best?

With the vacuum advance disconnected and the dist timing at 10 BTDC the engine RPM is ----, the manifold vacuum is----, and the RPM is---? Do this every five degrees of dist advance AND POST THE NUMBERS. It should be very interesting. Pete

By Pete 55Tbird - 12 Years Ago

It might help to understand what is going on if you can give more specific information. I have never seen an engine that had the same manifold vacuum reading if the RPM was constant but the ignition timing was changed. If I understand your other posts the manifold vacuum on your car is 20 inches and rock steady until just before it dies.

Confirm you are not using "timed vacuum" from above the throttle plates.

Can you put a manifold gage on AND a tach AND a timing light and take a series of reading starting from a cold engine and then advancing the timing in stages until you have the 27 degrees that you find works best?

With the vacuum advance disconnected and the dist timing at 10 BTDC the engine RPM is ----, the manifold vacuum is----, and the RPM is---? Do this every five degrees of dist advance AND POST THE NUMBERS. It should be very interesting. Pete

By peeeot - 12 Years Ago

Pete, I'd be happy to do that. Just to clarify, am I taking those readings (vacuum and RPM) with the engine at curb idle (off the fast idle cam), and doing the full process once while the engine is still cold and once when it's hot?

By peeeot - 12 Years Ago

So for about a month now my Fairlane has been in the care of a local shop. They are certain that the cause for the trouble is a loss of spark, but they (we) continue to struggle with an explanation for what's going wrong.

They say that the air gap between the rotor and dist cap is 0.150", and that consequently the coil is unable to reliably generate enough voltage to get a spark across the gap in the spark plug. I suppose that as the coil heats up its maximum voltage output decreases to the point that I have trouble symptoms, and that the rest of the time (before symptoms show up) the coil is working "wide open," causing it to run hotter than it should. They say that the coil makes a strong enough spark to jump 1/2" outside of the distributor, but they are not getting any juice out of the cap.

This theory makes sense, but since cap and rotor have already been replaced, the problem would have to be in manufacturing, and I have never heard anyone complaining about a similar issue. I am wondering whether there is perhaps some slight difference between the '57 distributor and the later, service-replacement unit you can buy at the parts store which makes the new parts the stores sell not quite right for the original dist. Anyone know anything about this?

By MoonShadow - 12 Years Ago

Have them check the ground wire in the distributor. Also the hard wire going from the points to the condensor. I've seen them break internally where they can't be seen. Chuck

By charliemccraney - 12 Years Ago

Did the problem arise after replacing the cap and rotor? If yes, then it could be the issue. If no, then it probably is not. It seems like the rotor could be shimmed to move it closer to the cap and test that theory.

By 57_ford - 12 Years Ago

I had a similar problem with my 272 in my old truck. It drove me nuts. Tried different dist. carbs etc. advanced the timing a lot nothing helped. I would put the timing light on it and it wouldn't stop blinking but I did notice when it missed the timing mark moved. I didn't think much of it at first. Thought it was caused by the miss it self. The fuel pump started to leak and when I took it off I put my finger in the hole that the fuel pump goes into and felt the timing chain. And noticed the timing chain was very loose. Changed the timing chain and gears and the problem was gone.

By bn - 12 Years Ago

That internal ground wire can be real tricky. It flexes as it follows the motion of the timing advance plate and over the years the wires can fatigue (break) while the insulation still looks good (if it has insulation). Checking its continuity may show it good while in reality it is bad when it is flexed in a particular position. Be sure and replace it with a wire designed to withstand many cycles of flexing.

By peeeot - 12 Years Ago

57 Ford, I just replaced the chain and gears less than 3k miles ago. The timing marks are nice and steady even when it misses, but it's a good thought!

bn, you're right, the only way to be certain about that wire is to replace it. I think. heh.

I hope to go take the car back from the shop tomorrow or, at the lastest, Friday. Then I will replace that wire.

I am also contacting internal combustion engine experts in academia to try to get a handle on how the engine can stand such extremely advanced timing; clearly, the mixture burns very slowly, but why? It may be a critical clue.

By peeeot - 12 Years Ago

I got the car back on Friday. It was missing so badly on the way home I had to pull over. I bypassed the resistor and it was smooth sailing the rest of the way, though I was expecting trouble at any moment.

I really thought the shop was on to something with the whole rotor-to-cap gap thing. I did my own measurements and agree that the gap was excessive. Amazingly, though there is no reference to this on any parts web site, there IS a different rotor available for this distributor, and Autozone sells it. All of the rotors the shop and I had tried were marked with an E on the firing bar. Something about that rang a bell to me. Some web snooping turned up the following info:

"In later GM vehicles with window style caps, there are two different gap specifications available, standard, and emissions.

Standard gaps are set to a spec of .100 and have a +/- tolerance of .030. These rotors have no marking on the end of the firing bar. These gaps have the least resistance of the two designs.

Emissions rotors have a shorter rotor firing bar length, to give a larger gap to bridge, to force the coil to make more spark energy, by having to overcome the larger terminal to tip gap. This was done to have the ignition coil work harder to make more volts from the coil, which ended up marginally increasing spark energy, but ended up just overloading the coil. Attempt was to make ignition output higher so it would help lighting off ever leaner mixtures, doesn't work well. Gaps for these rotors are usually set to .200/.250, and the rotor firing bar is identified with a letter "E". The large gap rotors are not the best for performance applications.

Not all small gap rotors are unmarked, example, NAPA RR167R is made by Echlin, is a short gap rotor, non-emissions, but the NAPA RR169R is a large gap rotor, has the E as well, so...best to measure the tip length and select the longer rotor tip when obtaining a new rotor. In the case of the RR167R, the E is for Echlin, the RR169R, emissions, somewhat confusing if you don't know what is what."

Of course, that was written about GM parts, but the E was there on the Ford rotor, so I thought, could be the same. Well, the non-E Autozone rotor was about 1/8" longer in reach than the others I had tried, so I thought for sure I had found the heart of all of this. Ultimately, even that has not resolved the trouble. I believe that most if not all of the intermittent missing has gone away with the new rotor. Also new is spitback through the carburetor, particularly if I snap the throttle open; I have never ever had that happen before. But, regardless, I can't idle the car in gear when hot, and I even had it shut off once or twice in today's tinkering.

Next, I will replace the primary wiring, one piece at a time, starting with the little ground wire inside the distributor.

By stuey - 12 Years Ago

i have nothing to offer but encouragement. this has gone on for a while now but think of the experience gained.

re the rotor gap, that stirs a distant memory from my motorcycle days when people used to introduce a coat button in the ignition lead. i never tried it but was told it made a better spark at the plug.

keep at it

wishing you a successful outcome

stuey

By aussiebill - 12 Years Ago

peeeot (9/29/2013)

I got the car back on Friday. It was missing so badly on the way home I had to pull over. I bypassed the resistor and it was smooth sailing the rest of the way, though I was expecting trouble at any moment.

Of course, that was written about GM parts, but the E was there on the Ford rotor, so I thought, could be the same. Well, the non-E Autozone rotor was about 1/8" longer in reach than the others I had tried, so I thought for sure I had found the heart of all of this. Ultimately, even that has not resolved the trouble. I believe that most if not all of the intermittent missing has gone away with the new rotor. Also new is spitback through the carburetor, particularly if I snap the throttle open; I have never ever had that happen before. But, regardless, I can't idle the car in gear when hot, and I even had it shut off once or twice in today's tinkering.

Next, I will replace the primary wiring, one piece at a time, starting with the little ground wire inside the distributor.

Good to continue on this journey with you. I wondered about the spitting back on snapping the throttle, with all the new fiddling by the shop, and change of rotor, how about resetting the timeing and check if spitting stops, that sounds like retarded timing to me? regards bill.

By John F - 12 Years Ago

You stated it ran good after bypassing the resister. I would start by replacing the resister, check the points and reset the timing and see how it does. You may have the answer already.

By peeeot - 12 Years Ago

Folks, AT LAST, I can report that this issue is fully and completely RESOLVED!

And, in total humility, the answer has been suggested repeatedly, and could have been addressed a long time ago.

As I said in my last post, I found a new rotor that decreased the rotor-to-cap gap, and while the intermittent missing seemed to have disappeared as a result, the car would still shut off suddenly and fail to run in gear when thoroughly hot.

So, I removed the distributor and thoroughly cleaned the base and clamp to make the best ground to the block possible. I also disassembled all of the wires internal to the distributor (breaker plate to ground, points to distributor terminal) and reattached the metal ends to new wire with solder. I did the same with the wire from the resistor to the coil. I replaced the wire from the distributor terminal to the coil with a new wire as well.

When I put it all back together, I ran through the usual battery of ignition system tests. As before, the voltage drop to the resistor was about .29V, and the voltage drop from the coil negative to ground was about .18V. Spec is 0.2 and 0.1, respectively. Not seeing any change, I drove to the gas station to fill up as I was nearly empty, but I did not expect any improvement. I decided to run the full test loop I have been using just for grins and when I got to the critical point, everything seemed OK. I got back to the driveway and the car was still idling in gear! I turned the idle in gear down to about 480 RPM and the car idled without a hiccup for ten minutes. Sweet, sweet victory!

So, today I drove it to work and covered about 75 trouble-free miles. Now, finally, I can think about other aspects of this project... but first, I'm just going to enjoy driving it Smile

Thanks for all of your patience, suggestions, wisdom, and encouragement. And, for all of you who suggested it (some of you multiple times)--you're entitled to a hearty "I told you so!" Wink

By MoonShadow - 12 Years Ago

Sounds like a combination of things from poor grounds to bad solder connections. Glad you've got it fixed. Now enjoy the drive! Chuck

By Meandean - 12 Years Ago

peeeot (10/1/2013)

Thanks for all of your patience, suggestions, wisdom, and encouragement. And, for all of you who suggested it (some of you multiple times)--you're entitled to a hearty "I told you so!" Wink

Yea! So glad this long ordeal is over. I can only imagine how freaking FRUSTRATING it had to have been. I'm sure you're extremely relieved.