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By Countrysquire - 11 Years Ago
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I just picked up a '55 Thunderbird that was restored a few years back, but has been sitting for the last year or so. Once I got it started, there was a pretty healthy gasoline leak from the pump, no doubt caused by the upstream electric pump. With the electric fuel pump disconnected and a new stock pump in place, it's running again, but it doesn't idle well. New plugs to replace the fouled ones didn't help a lot. I connected a vacuum gauge and it is between 10 and 11 inches hg, which seems awfully low. The timing seems to be advanced well beyond the 6 or 8 degrees that it should be, but retarding it makes it worse. When you rev it, it seems smooth and as powerful as you would expect, with vacuum in the 22-24 range.
The previous owner kept receipts of all the work that had been done, and it looks like a couple shops have tried to resolve similar issues with it. There has been a valve job with the heads resurfaced, new intake gaskets, carb overhaul, Pertronix ignition, etc. Compression is a little low, but consistent at 105 psi or so. The valves were set a little loose, so I reset them at .020 but that seemed to make the vacuum drop an inch or so. There is zero blow-by and no evidence of oil on the plugs, so I think that the rings are good.
Finally, sometimes it will idle as long as you like at 7-800 RPMs and is almost acceptable. Other times, one of the secondary barrels fills with fuel, eventually killing it by flooding. It has the original Holley 4000 teapot carb, which I have no experience with.
Anyway, it strikes me as having a vacuum problem that no one has been able to find as well as a carburetor issue. This is my first Y block, but I wouldn't think that it would be much different than diagnosing any other engine. That said, it's kicking my butt and I'm having to reach out to the experts.
Any help is appreciated.
Thanks,
Bobby
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By Meandean - 11 Years Ago
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Is it still 6V? If so, the Pertronix may not be putting enough spark to the plugs. I had beau coups trouble with the one I installed. I finally went back to points.
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By Glen Henderson - 11 Years Ago
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The dampers are know for slipping on the hub, I would set the timing using a vac gauge and not worry about the timing marks. Can't help you much with the t pot but there are others on here that can. Just be patient and someone will jump in with good advice. Best advice I could give is dump the 55 dist and go with a 57 later unit. If you search around here you can find a lot of information on the problems with the pre 57 dist.
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By speedpro56 - 11 Years Ago
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Some times the rear top large screw on the carb will not be tight enough and will leak into the back barrels causing the engine to overload and idle rough and stall the engine at times. Try setting the timing at 10 degrees if the damper has not slipped, the 3 to 6 degree recommended by ford didn't work very well and made the engine run a little sluggish. The teapots are bad for leaks if not taken care of but once fixed they run very well.
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By Countrysquire - 11 Years Ago
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Thanks for all the advice. The car is 12V and had the Pertronix installed after the problem was noticed.
Since the last post, I have reran the valves to make sure that they are at .020 and done a compression test. All the cylinders were between 112 and 128. Not high, but I would like to think it's enough to pull more than 9 inches of vacuum. What I keep thinking about is the timing. The marks on the balancer run from TDC to 10 degrees (I think). However, it wants t run at about 2.5 inches past that, which I would estimate about 25-30 degrees. Advancing it from there makes it ping, retarding it to the specified 8 degrees makes it feel very sluggish. When it's at TDC per the balancer, the rotor is pointed right at #1. One of the shops that worked on it pulled the timing cover to verify that timing hadn't jumped. Still, it sure makes me think that the cam is not synced up with the crank like it should be.
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By Talkwrench - 11 Years Ago
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Welcome ! Your in for a learning curve, we'll get to the problem don't worry. We may need to find out if your a purist or you don't mind changing a few things like the vacuum operated dissy you have in the 55, going to a later model etc etc.. Its not going to cost you an arm or leg but slowly does it..  
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By Countrysquire - 11 Years Ago
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I don't mind changing a couple things to get the car right. What's the point owning it if I can't enjoy it? My experience has been with small block and FE Fords, so the Y block is somewhat new to me. Again, I appreciate the sharing of knowledge and willingness to help.
Bobby
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By Pete 55Tbird - 11 Years Ago
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Bobby
With the engine at idle and a vacuum gage hooked up to the MANIFOLD advance the distributor to the MAX VACUUM that you can get. This will tell you if your engine timing is near what it should be. 9 inches of manifold vacuum cannot be right. Vacuum leak or retarted timing. Find out. It does not matter what engine, they are all very similar. Pete
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By Countrysquire - 11 Years Ago
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Thanks Pete. with it idling around 800 RPM, I could move the distributor 20+ degrees either way and the vacuum would struggle to get above 11 in hg. Also tried adjusting the air mixture screws for max vacuum, but it didn't make much difference either. The manifold had been resealed by a previous shop trying to solve the same problem. When checking with an unlit propane torch, there was no sign of a leak. I might try to cobble together some type of smoke machine tomorrow to see if anything shows up.
I would like to think that the engine builder lined up the dots on the timing gear instead of what the Y block requires, but with the balancer at TDC, the rockers on #1 are loose and the rotor lines up with #1 on the distributor.
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By Hoosier Hurricane - 11 Years Ago
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If it is a T-Bird engine with the correct front pulley, the timing marks are on the fixed part of the pulley and cannot slip. Does it have power brakes? If so, try disconnecting the vacuum hose to the the booster and plugging it. Sometimes the diaphragm in the booster leaks vacuum. In addition to what Speedpro said about the large plug on the back of the fuel bowl, there is also a brass transfer tube between the base and the bowl, sealed with O rings. If that leaks, fuel will run into the secondary bores. And speaking of secondaries, are they closing completely? If not, they become a vacuum leak as there is no idle circuit in them. Also, the vacuum hose to the wipers could become a leak, try disconnecting and plugging it.
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By Countrysquire - 11 Years Ago
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Thanks John. The timing marks are on the pulley. It does have power brakes, but I disconnected the booster and blocked it off to eliminate it as a leak source. I do not see any fuel leaking from the large screw, but occasionally there will be a little bit around the vase of the two vertical tubes. The only time I see the one rear bowl fill is when the secondary butterflies open. It will hold the fuel until I manually open the butterfly, so I think they are fully closing. While I do think the carb has issues that need attention, could it be bad enough to make the manifold vacuum half of what it should be?
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By Countrysquire - 11 Years Ago
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I'm still puzzled why the the timing has to be so far advanced for it to run. I had mentioned before that when the previous owner had it in a shop (foreign car shop, don't know how much they know about Y blocks) that they pulled the timing cover to check it. It could be that they were expecting to see the two dots on the gears lined up, which I understand is not correct for a Y block. So it may or may not be right. That said, with the balancer at the TDC mark, both of the rockers on the number 1 are loose, so the lifters must be pretty close to the bottom of the cam lobe. Also, when at the TDC mark, the rotor is pointing to number 1 on the distributor, but I guess that you can stab the distributor in any orientation.
I'm going to pull the rocker shafts this morning to make sure that none of the pushrods are bent. They spin freely when relaxed and all the valves look to travel as far as you would expect when the cam turns.
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By mac - 11 Years Ago
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i was having a lot of trouble getting mine timed, i'd rotate until i got tdc on the compression stroke, look at the rotor and it'd be pointing somewhere around 1 on the cap. wouldn't run. finally i was told to rotate the engine to 10 tdc (i basically guessed as my damper has no numbers on it), loosened the distributor hold down, and brought it counterclockwise until the rotor was pointing at #1 and the points were open. that got the engine running pretty well. i realize you don't have points anymore though, so i don't know how you'd know when the pertronix would be "open" or sending spark...
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By slick56 - 11 Years Ago
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Be aware that no.1 cylinder is the front passenger side, ie. on the left looking at the engine from the front of the vehicle.
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By yblock - 11 Years Ago
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remember if you upgrade the distributor you have few options re the tack drive(just 57 tbird)and the newer carb must go with it.like others the original 55carb and dist can work well. is your vacume advance ruptured? is the vacume valve for dist working? the earlybirds need lots of inital advance even when all elce is working ,sounds like some good advice re power brake and othe vacum leaks . get hold of a 55 56 motors repair manual they explain the carb and dist advance process. i had 2 55 birds and made the last one run great with original carb ,dist,and points and 6volt. 1st 0ne came with elct.tack so any 57dist worked and 57 int manifold and carb ran well but i prefered the the purest rout. be patent and it will be a fun project
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By Countrysquire - 11 Years Ago
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What do you mean by vacuum valve to disributor?
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By Countrysquire - 11 Years Ago
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Update: Pulled the rocker shafts and ensured that all of the pushrods are straight. Reset valve lash at .019" with everything cold. Started back up and valves were quieter, but vacuum now in the 7-8 range. The previous shop had it set at .035", maybe in an effort to increase the vacuum, not sure. Anyway, it still has the same miss. I did notice that the rotor had a ton of play (the shaft itself seemed fine), so I will see if I can find another rotor that fits better.
I did make a discovery that will hopefully lead to a solution. I scanned all of the inlet ports on the exhaust manifolds and realized that there's a problem with #5 & 6 cylinders. The other six cylinders were between 400 & 425 degrees, while #5 was about 190 and #6 was 285. Both cylinders were getting good spark and the plugs were not fouled when I pulled them yesterday. Compression of both cylinders were in the same range as all the others, so I think the issue is that that corner of the engine is not getting enough fuel for combustion to occur. That has to point to either a carb or intake issue, I would think, but would sure like some other opinions.
Thanks again for all of the advice.
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By Hoosier Hurricane - 11 Years Ago
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Doesn't sound like a carb issue, because 5 and 6 are fed from different sides of the carb. Cylinders 1,4,6,and 7 are fed from one side of the carb, 2,3,5, and 8 from the other. A lack of intake manifold seal at the left front could be a problem Hey! I just got an idea. If the front valley cover bolt is sticking up too far, the manifold rests on the head of the bolt and doesn't pull down tight. A lot of front ears are broken on Y manifolds because of this. See if you can slide a thin piece of metal or cardboard between the bolt and the manifold.
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By Countrysquire - 11 Years Ago
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Did a test for vacuum leaks this afternoon with a homemade smoke machine, but didn't see anything leaking. I'm going to pull that valve cover again and watch the rocker movement on #5 closely.
I'll look closely at the valley cover bolts and see what I have.
Thanks.
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By Countrysquire - 11 Years Ago
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OK, the issue on 5& 6 is solved. I seemed to swap those two plug wires when i reassembled it this morning. I meant to do a continuity test then, but got sidetracked and forgot. Vacuum is back in the 11 range, but it has a bunch of initial advance. When I crawled underneath to investigate an exhaust leak, I did notice that the rear main seal is leaking badly and there's a good bit of smoke vapor coming from the road draft tube, which makes me think it must be seeing a lot of crankcase pressure. Not good.
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By Pete 55Tbird - 11 Years Ago
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Next thing to check is if the camshaft has become flat. Pete
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By NoShortcuts - 11 Years Ago
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Previous suggestions are all good. More thoughts…
The ’55 Holley 4000 has a small, mushroom shaped, vacuum diaphragm on the passenger side of the carburetor base toward the front of the carburetor. This device is a ‘spark control valve’ and is part of the distributor vacuum advance system. Look for it directly below where the air cleaner housing sits, in front of the vacuum secondary diaphragm throttle shaft connection, and adjacent to the idle mixture screws. IF the diaphragm in this unit is bad, it will cause a vacuum leak. _________________ Previously mentioned… the diaphragm in the vacuum control canister attached to the distributor could be defective. Potentially, it is 59 years old! Again, bad diaphragm, vacuum leak. The ignition advance on the ’55 ‘Bird is TOTALLY vacuum controlled. _________________ Wherever the vacuum take-off for the windshield wiper ‘motor’ is located on the intake manifold, it leads to the fuel pump. Weird, huh! In addition to drawing and pumping fuel, the ’55 fuel pump has a second diaphragm that boosts the vacuum to the windshield wiper ‘motor’. Although you replaced the pump, the diaphragm that does this could be defective, again causing a vacuum leak. Block the intake manifold vacuum take-off to rule this second diaphragm out. _________________ Holley 4000 carburetor shafts are prone to wear more than some. This can cause a vacuum leak,also. On the ’56 Power Pack set-ups and the ’57 ‘E’ set-ups (2x4 carbs), high idle speeds that can’t be brought down are often the result of worn throttle shafts or shaft bores. Squirting some 30 weight oil on the ends of the primary and secondary throttle shafts will rule this out if the idle speed drops.
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By Countrysquire - 11 Years Ago
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Thanks for the suggestions and continued support.
- I have been checking the vacuum by disconnecting the line that runs from the intake manifold to the fuel pump and attaching my gauge to that line.
- I have blocked off the brake booster, no change.
- I have disconnected the vacuum line to the distributor and didn't see a change. When connected, the timing does advance with RPMs.
- The mushroom shaped diaphragm on the side of the carb seems to move in about 1/16" or so when revved.
- Vacuum is idle speed and ignition advance dependent. Initial advance is somewhere around 25 degrees. With the idle at ~750 RPMs, vacuum is ~7"hg. At 1000 RPMs vacuum is between 10 & 11"hg.
- Placing the car in gear will drop the idle from 1000 to about 450, barely enough to keep running.
- All the valves look to be opening the amount, but I have not measured yet to see if they are within spec.
- The car seems to run best at ~25 degrees initial advance. Move it much further and it detonates under a load, retard it and it's really sluggish.
- When the car is idling, there's a steady stream of fumes coming from the road draft tube. Is this normal?
I haven't checked compression since I have adjusted the valves, but plan on doing that this evening. Also, I will do a dry and wet compression check to see if it's a piston ring issue. The first test I did was dry and the cylinders were all in the 110-128 range.
At this point, I think that the problem is either the camshaft orientation or an issue with the rings.
The motor looks like it's been rebuilt (I know that the heads have been), but that doesn't mean anything. Maybe the engine assembler installed the rings wrong, or maybe they are all stuck because the car has done a lot of sitting after its restoration. Or maybe it was only painted and not rebuilt.
The fact that it needs so much advance makes me think that the timing set may have been installed wrong. A previous shop had pulled the timing cover to inspect this, but it's a foreign car shop, so their Y block experience is probably very limited. It could be they were looking to find the dots on the gears lined up at 6 & 12 o'clock like every other V8 that I've ever worked on. If I understand correctly, the dots on the gears should both be around 3:00 with 12 links between them.
Sorry for the long post, but I wanted to keep those of you who have been helping me up to date.
Thanks again,
Bobby
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By Hoosier Hurricane - 11 Years Ago
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Bobby:
There should be 12 PINS between the dots on the timing gears, 6 links. My latest thought is that maybe your vacuum gauge is lying. Have you tried it on another car?
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By Countrysquire - 11 Years Ago
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12 pins, not links, thanks. I did try the gauge on my old Nissan truck and it is rock solid around 22", just like you would suspect.
Here's a link of it running. The valves sound much louder in the video than they do in real life.
http://www.youtube.com/watch?v=vOMI_Hp88oE&feature=youtu.be
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By charliemccraney - 11 Years Ago
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It's hard to tell a whole lot from that video because of the way the microphone picks up sound and the way the frame rate can interfere with the movement of the vacuum gauge. Judging as best I can by the exhaust sound, something is definitely wrong if it is a stock cam. The 15" hg at 800 rpm is not unusual for a mild cam, though I would expect your compression pressure to be much higher.
In an earlier post, you asked "While I do think the carb has issues that need attention, could it be bad enough to make the manifold vacuum half of what it should be?" Yes, a poorly tuned carb, either due to wear or the tuner can cause all sorts of problems, including decreased vacuum. However, the low compression does still point to another issue. Given that you don't know much about the engine, I think it is probably just worn out and getting to be time for a proper rebuild.
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By Countrysquire - 11 Years Ago
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That's actually about 6" of vacuum in the video. The numbers on the outside of the dial are metric.
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By Countrysquire - 11 Years Ago
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Well, tore off the front end and didn't find what i was hoping to find. The timing is oriented as it should be, so I guess that means it's the rings. I had been contemplating pulling the engine anyway to repair leaks and freshen up the restoration, so why it's out why not freshen up the engine so that I know what I have.
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By Hoosier Hurricane - 11 Years Ago
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Maybe it's just the camera angle, but that chain looks a little loose to me. Maybe during the overhaul the main bearing bores were align bored, which moves the crank closer to the cam.
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By Countrysquire - 11 Years Ago
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I haven't measured the play in the chain with a ruler yet, but it looks to be about 1/2".
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By Ted - 11 Years Ago
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Loose timing chains can be responsible for up to 8° of cam retard. If the camshaft was already on the retarded side when first installed, then the loose chain simply compounds this. I’ll suggest degreeing the camshaft before removing it just to verify both the camshaft specs and where it’s installed. This could answer the question about the low compression readings.
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By Countrysquire - 11 Years Ago
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Thanks Ted. I have had a degree wheel, new in the package, that's been sitting in my toolbox for years. Guess I have an excuse to finally learn how to use it. Would you recommend putting a new timing chain on it before I do this? I haven't done an actual measurement yet, but it looks to have about 1/2" of slack, so I would like to replace it before it goes back together.
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By charliemccraney - 11 Years Ago
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The degree wheels usually come with bushings to fit a variety of crankshafts which does not usually include the Y-Block. You will need to drill one of the smaller ones to fit or have a bushing made.
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By Countrysquire - 11 Years Ago
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I was helping my son with his car last night, so no updates other than I did check the timing chain and the play was 5/16".
I do plan on doing a leak-down test as part of my testing to decide how far to go while I have the motor out. That said, I'm on the slippery slope of "while the motor is out, why not do X". The time and expense of pulling it all the way down while it's on the engine stand is not great. If the cylinders are within spec, a simple hone and new set of rings is simple enough. Testing should tell me if I need to go that far, but my preference would be not to pull the heads and pistons if I don't need to. I will be installing a new timing set, and probably a new cam and lifters. We'll see what more testing tells me.
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By The Horvaths - 11 Years Ago
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You' may well find it would be best inverting the block (literally) if you wish to change the lifters.
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By 314 - 11 Years Ago
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tim McMaster has a nice video on degreeing a yblock cam.google it.
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By Hoosier Hurricane - 11 Years Ago
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Country squire:
I believe I would degree the cam as is, so you would have an idea whether or not cam position is the problem. Would be a shame to replace the timing set and find that you have exactly the same symptoms. Also, 5/16 doesn't seem to be excessive slack to me.
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By charliemccraney - 11 Years Ago
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Countrysquire (3/5/2014)
That said, I'm on the slippery slope of "while the motor is out, why not do X". The time and expense of pulling it all the way down while it's on the engine stand is not great. If the cylinders are within spec, a simple hone and new set of rings is simple enough....
It's not really a slippery slope if if you don't give in to temptation and decide to do only what needs to be done.
What is more important than the cylinder spec is the piston clearance. The cylinder can be within spec but worn pistons bring the clearance out of spec so you need to be sure to check both.
You should go ahead and install the timing set to see if that brings your compression pressure back up. If it does, then things are probably good enough on the bottom end and you don't have to pull the engine from the car and the new cam and lifters will be going down that slope.
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By Countrysquire - 11 Years Ago
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Hopefully I will have time to do a leakdown test this evening. I'l have to do it cold, but that's my only option right now.
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By Countrysquire - 11 Years Ago
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Well, hmmm. OK. Had a little time this evening to look at the motor a little more. The dots on the cam & crank gears were at 3:00 with twelve pins between them, just as in the picture from a couple days ago. Used a piston stop and found exact TDC, then installed the degree wheel. Popped of the valve cover and noticed that the valves on #1 weren't loose, so the engine was on the exhaust stroke. Turned it 360 degrees and the cam gear dot was at 9:00, as you would expect. When I popped the distributor cap, I see that it was 180 degrees from #1. Turned it again to get the rotor pointed at #1 and that leaves the cam gear dot back at 9:00.
Can you install the cam in a Y block 180 out, or is it only possible to install the distributor that way, like on other motors? Either way, how could it run this good with something 180 out?
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By The Horvaths - 11 Years Ago
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It sounds like the cam is right, you counted the dots. The distributor can go in as many ways as there are teeth in its gear.
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By charliemccraney - 11 Years Ago
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Countrysquire (3/6/2014)
Can you install the cam in a Y block 180 out, or is it only possible to install the distributor that way, like on other motors? Either way, how could it run this good with something 180 out?
If the timing set is installed correctly and the cam is ground correctly, no. You didn't find exact tdc with only the piston stop. You need he degree wheel for that, which you seem to have installed after you thought you found tdc. That is probably why the valve was open slightly.
It wouldn't run 180 out.
Does the degree wheel have instructions? Follow them!
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By Countrysquire - 11 Years Ago
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The degree wheel was installed first. I used the piston stop turning the engine both directions, and used the degree mark half way between those two for exact TDC. While at TDC on the compression stroke, the contact of the rotor is at #6 on the distributor. It lines up with #1 on the exhaust stroke, which is when the timing dots are "aligned".
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By charliemccraney - 11 Years Ago
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If the distributor rotor is pointing at #6 when #1 is at tdc on compression, then it is 180 out. I have trouble believing that because I've never had an engine do anything that I would even remotely say is running when the distributor is off like that. The fact that you have timed the engine is also evidence against it being 180 out.
If you forget about the degree wheel and piston stop and just turn the engine until the valves on #1 , front passenger's side, are closed, and you have clearance between the rocker and valve, is the dot for the cam on the driver's side or the passenger's side? Where does the distributor rotor point?
Something else that can be contributing to your problem is valve train wear. Take a look at all of your adjusting screws. They should all be adjusted very nearly the same. If one is in or out farther than the rest then it is a clue that something is going on with that valve or the related components.
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By Countrysquire - 11 Years Ago
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With both valves closed and rockers 'loose' on #1, the cam gear dot is on the passenger side at 9;00 and the rotor is pointed at #6.
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By charliemccraney - 11 Years Ago
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Then the distributor is 180 out. It should be pointing at 1 when 1 is at tdc on compression.
I'm not sure about the relation of the dots, if 3:00 or 9:00 is compression.
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By Ted - 11 Years Ago
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Most timing sets for the Y’s have the 12 pins aligned with the #6 cylinder coming up on the compression stroke at TDC. That simply fools you if trying to put the distributor in place thinking #1 is at TDC compression without first checking the lobe orientation first. In these cases, I simply install the distributor with the rotor pointing at #6 in the cap rather than #1 if not going to the trouble of rotating the engine through another revolution.
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By Ted - 11 Years Ago
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Countrysquire (3/4/2014)
.....Would you recommend putting a new timing chain on it before I do this?
I agree with John (Hoosier) on using the existing and well used timing chain and gears when checking the camshaft phasing. This will give a more accurate picture of where the camshaft is sitting now and will help to isolate a potential reason for the lower than normal compression readings. When reinstalling the camshaft, then re-degree the camshaft using the new timing set as manufacturing variances in the new gears can have the cam timing changed up significantly from where you were with the old set.
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By Countrysquire - 11 Years Ago
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Thanks Ted. That makes sense, and it appears to be how it's installed, but I expected to see the rotor pointed towards #1 while at TDC with both #1 valves closed.
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By Ted - 11 Years Ago
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Countrysquire (3/6/2014)
Thanks Ted. That makes sense, and it appears to be how it's installed, but I expected to see the rotor pointed towards #1 while at TDC with both #1 valves closed.
Have you checked the damper to insure it hasn't slipped?
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By Countrysquire - 11 Years Ago
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It's a fresh rebuilt Thunderbird damper with the numbers on the pulley. Plus, I used a degree wheel and piston stop to find TDC.
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By Ted - 11 Years Ago
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Ooops. Forgot. Seems like you had already mentioned earlier it was a Thunderbird damper. In that case, TDC should be reasonably close. Something else you can do is put either the #1 or the #6 cylinder with both valves at overlap equally (straight edge across the top of them so they are level) and check that the TDC on the damper is reasonably close to the pointer. It should be within 4-5 degrees and with a loose chain, possibly with the TDC on the damper being slightly past or after the pointer. This is simply a quick and dirty check for cam phasing for engines in cars without going to the trouble of doing the degree wheel / dial indicator bit.
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By charliemccraney - 11 Years Ago
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So the timing set seems to be installed correctly.
Another thing, have you traced all of the plug wires? While #1 is typically a certain location in the cap, the installer of the wires can put #1 wherever he wants and as long as all of the wires follow the firing order and the engine can be timed, it will run just fine. So maybe the wires are not installed correctly but it is still functionally correct which is why it appears to be 180 out yet still runs.
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By Countrysquire - 11 Years Ago
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Cam overlap on all cylinders is the same, and it's about 5 degrees earlier than TDC. Also, it looks like there's about 2 degrees worth of slack in the chain. I wouldn't think that's enough to cause compression and vacuum issues. 6" of vacuum is pretty piss poor for a stock cam. I checked cylinder by cylinder per the firing order, 90 degrees at a time and the overlap followed on the cylinders per firing order. Measurements were taken with a metal ruler across the valve retainers, giving me two contact points on each valve.
When turning the engine by hand, you can hear the air blow into the oil pan pretty easily. Maybe the rings ain't as good as I hoped, but my experience doing that has been with new engines that I've built, so I'm sure they are tighter. I've not done a leakdown test yet, but I guess that will be next.
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By Ted - 11 Years Ago
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Have you checked your compression gauge for accuracy? Was the throttle opened up during the compression test? Adding oil to the cylinders and redoing the test will confirm if the ring seal is part of the problem regarding the low numbers. Your test numbers are well within the required 10% for the values between the highest and lowest so that part is good.
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By Countrysquire - 11 Years Ago
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Ted, I was headed that direction with the compression test when the starter gave up, so I'm waiting for it to get back from the rebuilder. I did check the vacuum gauge on a known good engine to verify it, but I have not done that with the compression gauge. I will do that before my next round of testing.
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By Countrysquire - 11 Years Ago
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Finally had time to do a cam timing check this afternoon, and here's what i came up with:
Intake valve opens at 29° BTDC vs. Ford spec of 12° BTDC
Intake valve closes at 85° ABDC vs. Ford spec of 54°ABDC
Exhaust valve opens at 89° BBDC vs. Ford spec of 58° BBDC
Exhaust valve closes at 41° ATDC vs. Ford spec of 8° ATDC
All opening and closing measurements were taken at .020" to compensate for valve lash, dial indicator inside of pushrod cup.
The intake lobe center angle came out to 112°.
Intake valve lift measured .278" (.298" - .020") vs. Ford spec of .264"
Exhaust lift measured .281" (.301" - .020") vs. Ford spec of .262"
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By charliemccraney - 11 Years Ago
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Those look like numbers for a decent sized cam, which explains the exhaust sound and low vacuum. It may also explain the low compression pressure, if the static compression was not increased to compliment the cam.
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By NoShortcuts - 11 Years Ago
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Countrysquire (3/10/2014)
Finally had time to do a cam timing check this afternoon, and here's what i came up with:
Intake valve opens at 29° BTDC vs. Ford spec of 12° BTDC
Intake valve closes at 85° ABDC vs. Ford spec of 54°ABDC
Exhaust valve opens at 89° BBDC vs. Ford spec of 58° BBDC
Exhaust valve closes at 41° ATDC vs. Ford spec of 8° ATDC
Those are 'WoW!' numbers to me! No wonder the vacuum gauge readings are L-O-W!
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By Countrysquire - 11 Years Ago
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Yeah, assuming that I'm doing the measurements right, those numbers are way out there. But it does explain the low vacuum and compression readings, plus how far the cam has to be advanced for the car to run decently. I think that I've convinced myself to go ahead and hone the cylinders and put in a new set of rings while I have it out of the car. Not much more expense and I'll know exactly what I have.
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By Lord Gaga - 11 Years Ago
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If the engine is out, I would remove the welch plug @ the rear of the cam and look for after market manufacturer's I.D.
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By NoShortcuts - 11 Years Ago
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IF you're going to use the 'Bird on the street, consider changing to a milder cam, too. 
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By Countrysquire - 11 Years Ago
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Haha, it's easier to laugh now that it looks like I've found the main problem. Once the cam is out, I'll make it available to the highest bidder...
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By Countrysquire - 11 Years Ago
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I'm wanting to go back with a stock cam and I see that Carpenter, C&G, and Joblot both have NOS cams for $70. Any reason not to go with one of these and a set of the Comp Cam lifters?
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By slick56 - 11 Years Ago
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Countrysquire (3/10/2014)
I'm wanting to go back with a stock cam and I see that Carpenter, C&G, and Joblot both have NOS cams for $70. Any reason not to go with one of these and a set of the Comp Cam lifters?
I would go with a stock or mild cam and lifters from JMummert.
At the very least, you know you will get USA made products, customer service, and you will support
a Y-Blocks forever member who has done wonders for the resurgence and longevity of this engine.
http://www.ford-y-block.com/
Just my 2c worth.
.
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By Oldmics - 11 Years Ago
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The new stock grind cams that are now availiable were patterned after the last version of Y Block cam availiable from Ford.
In late 57 early 58 the Y Block cam was "detuned" and a new crippled DOG was born. These are all that are availiable from the general sources.
Suggest you follow some of the other guys advise and look for a good aftermarket replacement for a driver engine.
John Mummert would be the guy to speak with who can sell you the correct item.
Oldmics
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By Ted - 11 Years Ago
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Lord Gaga (3/10/2014)
If the engine is out, I would remove the welch plug @ the rear of the cam and look for after market manufacturer's I.D.
Not all cams are marked regarding specs or manufacturer. Reverse engineering the cam specs with a degree wheel and dial indicator placed on the intake/exhaust lifters is one way to determine the cam specs on those cams not ‘stamped’with identifiers.
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By Ted - 11 Years Ago
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Countrysquire (3/10/2014)
I'm wanting to go back with a stock cam and I see that Carpenter, C&G, and Joblot both have NOS cams for $70. Any reason not to go with one of these and a set of the Comp Cam lifters?I’ll second the comments regarding the new replacement stock cams. I recently dynoed a stock 292 build with one of those cams and it made a whopping 153 HP. This is an engine that was built back to 1963 specifications so the camshaft wasn’t all the problem but a major contributor just the same. If you can find a replacement 1957 camshaft, then that would be a suitable camshaft for an upgrade in performance without sacrificing oem idle and fuel economy characteristics. There are plenty of aftermarket cams out there that will also give good idle and vacuum attributes so be sure to look at what's available before 'settling' for the 1958-1964 spec'd camshaft.
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By Countrysquire - 11 Years Ago
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Ted,
The available NOS cams have the 1958 part number B8A-6250C. The cam Mummert sells is based on the '64 truck cam C4TZ-6250A, which sounds like is the better option for a few bucks more. I will give him a call today and see what he recommends.
Now I have to decide what else to do while it's out...
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By Countrysquire - 11 Years Ago
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OK, now that it looks like the main problem has been found thanks to everyone's helpful advice, I need to decide what to do once I have the engine out. Obviously, I don't want to have to pull it a second time because I didn't fix something I should have, but I don't want to do unnecessary work either. A new cam, lifters, and timing set will be installed, but I haven't decided if I should pull the heads for inspection (they were recently reworked) and pull the pistons, then hone and re-ring. Of course, that means inspecting and measuring the bearings as well.
To recap:
- Vacuum around 6-8" hg at idle, compression 110-128 psi on cool engine, dry cylinders, and throttle closed.
- No blow-by out of breather, good bit of fume from draft tube (no PCV system), no sign of oil dripping from draft tube.
- What smoke there was from the tail pipes looked to be fuel related, not oil.
- Old plugs looked pretty good, not fouled from fuel or oil.
- When turning the engine over by hand with the front cover off, you can hear the air escaping into the pan. Reaching TDC compression is easier on some cylinders than others.
- While I assume that there aren't that many miles on it since rebuild, 5/16" slack in the timing chain might prove me wrong.
- Oil pressure at idle is about 25-28 psi when warm, at idle.
So what say ye? Should I tear it all the way down? The additional cost of rings and gaskets is about $150, which might be cheap insurance. Assuming that the bore is round, in spec, and not tapered, can I introduce any problems with a hone and re-ring?
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By lyonroad - 11 Years Ago
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If you haven't already done so, pull the oil pan and see whats in the bottom. I was in the same boat as as you. I had a 55 -292 that was supposed to have been rebuilt. The top end was spotless, so I thought the rebuild had likely been done. When I pulled the pan (I had to go from a rear sump to to a front sump) I found a lot of sludge in the bottom of the pan. That got me suspicious so I pulled the heads. There was a significant ridge indicating that the latest rebuild if ever was many many miles ago. When I sent the block out for a rebore they had to go 60 over.
It does not pay to assume!
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By Countrysquire - 11 Years Ago
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Mark,
That's exactly what I fear. Even if I have to go as far as boring it, stock cast pistons are cheap enough. The starter repair shop just called and told me that the starter is ready, so I could check compression again with looser valve lap, but I'm leaning toward getting the peace of mind from knowing exactly what I have. Plus, the starter had a nice coat of paint, but it looks like it hadn't been apart since it was new. That could be indicative of how the engine was done...
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By charliemccraney - 11 Years Ago
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Countrysquire (3/11/2014)
- Vacuum around 6-8" hg at idle, compression 110-128 psi on cool engine, dry cylinders, and throttle closed.
- When turning the engine over by hand with the front cover off, you can hear the air escaping into the pan. Reaching TDC compression is easier on some cylinders than others.
If the throttle was closed, then that also contributes to the low compression pressure reading. The throttle should be wide open during that test. I bet if the throttle was open it would jump to around 150 or more, which is good.
You should perform a leak down test before you dig in too deeply. If that turns out good, then I would not touch the rings or valves for now because everything else sounds pretty good.
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By Countrysquire - 11 Years Ago
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I guess that I should try to build a leakdown tester, it seems simple enough and I have most of the parts already. I hate to go spend $100 for a tool that tells me if I need to spend $100 for parts.
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By Oldmics - 11 Years Ago
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A bunch of the parts for a leak down tester can be obtained/utilized from certain compression gauge units.
Oldmics
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By Countrysquire - 11 Years Ago
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Thanks Oldmics, that's my plan. I believe I have everything I need but some quick setting epoxy, so I should be able to put one together this evening. The leakdown test will have to be done cold, but it ought to tell me something.
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By Countrysquire - 11 Years Ago
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OK, leak tester built and it appears to work, based on a lot of correlation with the compression test. All the cylinders but two had between 25 & 35% leakdown. One cylinder only had 6%(!), and one had 75%. That one might have a problem. I went back and checked it again and got the same reading. Moving the crank back and forth made no difference, nor did tapping the valves. I followed that with a couple squirts of oil and retested. The pressure came out about 5 psi, but you could hear the air blowing through the oil. I guess this tells me that I better go ahead and open it up while it's out of the car.
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By NoShortcuts - 11 Years Ago
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Although it is said that it can be done, those on this Forum that say they have done it, say they would NOT do it again. Do what? Change a Ford y-block cam and lifters without the engine being upside down.
Pulling the engine on a ‘Bird or any other vehicle is time consuming and work.
Money and time do not grow on trees. However, having to do something twice is one of those things that really irritates me, especially if I knew ‘I-should-have’ done something that I didn’t.
Too many people who rebuild engines do not KNOW the ins-and-outs of the y-block Ford engine that went out of production in this country 50 years ago.
ALL manufacturers' engines and ALL engine series have nuances. With a rebuilt engine, IF you don’t know who rebuilt it, IF you don’t have documentation of the work done (repair shop bill), what have you got?
Consider your plans for the car. IF you’re going to keep it, since you’re going to pull the engine to change the cam and lifters, consider taking it ALL apart. Disassembling, cleaning, measuring, and reassembling the entire engine and its components like the oil pump, distributor, and the carb will give you the peace of mind of KNOWING what you’ve got and HOW it was done.
At an earlier time, I had the experience of disassembling a never fired Ford re-manufactured 312 from an authorized Ford re-builder. Everything checked out as being correct EXCEPT that USED concave-faced lifters were installed with a new camshaft, mixed length pushrods were installed with the rockerarm assemblies, and the rockerarm assemblies had mixed ratio re-bushed rockerarms. I wasn’t impressed with the mixed valve train components, but was shocked that an authorized Ford re-manufacturer would push an engine out the door with used, obviously concave, valve lifters mated to a new camshaft.
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By Countrysquire - 11 Years Ago
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The engine was coming out either way because of the needs to freshen up the restoration, plus a significant oil leak at the back of the engine AND a leaking transmission. Like I said earlier, the last thing I want to do is do it twice. I would hate to pay a shop to do it, but this is all work I can do myself for not a lot of money. Well, do it myself with the help of the Y block community.
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By Outlaw56 - 11 Years Ago
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com check
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By NoShortcuts - 11 Years Ago
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Hi Bobby, When you first posted you mentioned that this was your first Ford y-block.
Recently, you’ve mentioned information from John Mummert's web site at www.ford-y-block.com IF you haven’t already seen it, look at John Mummert’s listing of common y-block assembly errors found at www.ford-y-block.com/assemblyerrors.htm
Other treasure troves of Ford y-block information from our Forum members are: - Tim McMaster’s web site at yblockguy.com
Hope you find these of help going forward. 
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By Countrysquire - 11 Years Ago
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Thanks Charlie. I've been studying all three of those websites, as well as this one. Plus, Tim has been helping me directly via PM. Right now the only decision that I have left is whether to pull the engine with the transmission or without.
Now that I've done a search, it looks like it is best to pull the engine separately.
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By Oldmics - 11 Years Ago
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With a Bird,if you have an engine hoist with enough height or some sort of crane where you can get the engine and tranny combo up high enough,you will save yourself some time doing the engine and tranny removal in one fell swoop.
Otherwise picking each piece out individually would be best.
Don't ask how I know !!!!!!!!!
Oldmics
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By Countrysquire - 11 Years Ago
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I will more than likely be pulling it myself, so separating the two should make it more manageable for me.
Will a tailshaft plug for a modern car (~1.5") work on the Fordomatic when I go to pull it?
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By NoShortcuts - 11 Years Ago
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Countrysquire (3/12/2014)
I will more than likely be pulling it myself, so separating the two should make it more manageable for me.
Will a tailshaft plug for a modern car (~1.5") work on the Fordomatic when I go to pull it?
The outside diameter of a '55-'56 Fordomatic drive shaft yoke is 1 1/2 by my tape measure, Bobby.
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By Countrysquire - 11 Years Ago
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Thanks.
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By Countrysquire - 11 Years Ago
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OK, the engine is out and everything but the rotating assembly has been taken apart. Here's my initial observations while tearing it down.
- Relatively clean inside, piston tops have a bit of carbon, more than I would have expected.
- Flat top .060" over pistons, no ridge at the top of the cylinders, just a layer of carbon.
- The cylinder walls have a nice glaze, no crosshatching is visible.
- The cam is out, and it's labeled CRANE F-294-2. A search of Crane's website and a Google search don't come up with anything. I did find some stuff about an F-294 cam for an FE, but no telling if it has the same profile.
- Once I get the garage back in order, I will pull the bottom end apart, starting with #4 (the one with 75% leakdown). I'm guessing the ring lands are full of carbon, but we'll see.
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By Countrysquire - 11 Years Ago
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#4 piston is out, but the rings weren't stuck like I was suspecting. However, the compression ring gap overlapped about 50%, so that should explain the leakdown for that cylinder.
I did a quick check on the bore and came up with 3.860", which can't be right. I don't have a bore gauge, so I have to do it with dividers and caliper, but that should be close enough for a rough measurement. I triple check, even changing calipers, but get the same reading. How could it be .110" over and be running .060 pistons? Could this be a 312? So I check and see the stock bore for a 312 is 3.800". Looking at McMaster's & Mummert's sites confirms that it's a 312. Casting number is ECZ-6015-C and it has ECZ main caps. The heads are the ECZ-G.
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By NoShortcuts - 11 Years Ago
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Well… some things DO work out better than expected! 
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By Hoosier Hurricane - 11 Years Ago
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I believe that's the old school Crane I have in my race car. Not very streetable. I have an old Crane catalog. What specs do you need? You have already checked it with a degree wheel.
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By Countrysquire - 11 Years Ago
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Probably even less streetable with stock pistons. No worries, it's headed to Oregon Camshaft as a core, if they can use it.
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By Countrysquire - 11 Years Ago
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By yblock - 11 Years Ago
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1 and 6 wil both be tdc at the same time,remember 1 is always on pasenger side,posibly builder not familure with ford and timed cam to#6. i have a 292 short block i just finished and double checked 1and 6 ar both tdc .and with cam and crank on keys cant see how that coud be out.
cliff
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By yblock - 11 Years Ago
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do not know wher you live but i use scadbolt cams(regrinder) he is a wealth of yblock info,just had a regrind to 1957 merc profile,he is in vancouver canada. he has some cores the 1 he just did was a groved for rocker lube. i delt with him when working for a cat dealer and my backyard engine rebuilding. Never had a failure. has a early iskey profile i used on a 55bird with std trans it was wild ,tho no good for auto. phone him 604 738 9505. call after 2pm he will give you advise and guidence,tell what enfine and trans. you wont go wrong. he charges 130 cnadian as long as you have a core, also refaces lifters tell him you talked to cliff tate
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