OldTGuy, I have manual brakes.312T85Bird, I always use a dwell meter to set the points. Dwell is set at 26*.

Today I tried the absolute last things I could think of. I bought another rebuild kit and pulled the air horn to check the booster passages for the hundredth time and to replace the little gaskets they seat on. As has been the case all along, there was no trash or sediment in the bowls or in any of the passages. I wanted to replace the gaskets because they looked wet and I thought maybe some fuel was short-circuiting past the idle air bypass and air bleed, resulting in an over-rich idle mixture. The gaskets were dry after that but no change was evident. So, since the original carb had a different set of booster venturis (a superceding part number according to my data sheet) and metering rods (same), I swapped the primary boosters and metering rods into the "new" carb after making sure they were clean and clear too. There was a slight change in which setting the engine preferred but the symptoms were the same in the end.

So, I am abandoning the '57 AFB. I hate that I'm abandoning it because I cannot come up with a satisfactory explanation for why. The only conclusion that I have left to draw is that the non-adjustable aspects of calibration, specifically the idle jet size and the bypass, economizer, and air bleed hole sizes, are incorrect for satisfactory operation with modern fuel. This troubles me greatly because every other old car I have owned ('59 galaxie, '59 Thunderbird, '66 Mustang, '63 Comet, '77 Malibu, '62 Chrysler, '70 Dodge, etc) and really any other one I've worked on with original equipment carburetors, some with obvious wear in the throttle shafts, has been able to perform satisfactorily with original spec calibration and nothing more than cleaning and a rebuild kit. The '70 Dodge is a daily driver right now with its original carb and at least 120k miles.

I have an autolite 4100 on its way to me now. Perhaps foolishly, I bought a correct '57 312 unit. Here's to hoping there will at least be a different set of problems in place of the present ones.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Did you try some of the suggested exhaust problems or heat riser issues / suggestions?

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

I know the heat riser itself is not an issue because I removed the butterfly valve. Only the shaft remains. I have not put any potatoes in the exhaust, but I am confident that the exhaust itself is not at fault.

I just went through the valve adjustment carefully, using the 1/4 turn method which I just discovered. I really liked it! I had done it previously with a very narrow, small set of feeler gauges that came with a points set I bought one time. I felt like my results were more consistent using the 1/4 turn method, and certainly the valvetrain sounded the best it ever has when I was through. Thanks to this forum for that tip!

Unfortunately, it didn't fix my problem.

Things have changed enough overall that I think it's worth starting from scratch now. If it would be more appropriate to do so in a new post, I'd be happy to. If not, here are the current symptoms:

1. When the engine is thoroughly warmed up, the car idles beautifully until it is put into gear, at which point it stalls immediately.
2. If the car is driven for a while, when I come to a stop, it will probably idle nicely for 5-10 seconds, then surge for about 5 seconds, then stall.
3. If I'm rolling along with minimal throttle, say, steady 25 mph, and I stab the pedal to maybe 50%, it will respond immediately with a rush of power which immediately becomes rough and uneven. If I hold the pedal steady, it will fight its way through the roughness until the engine speed reaches something like 2500 rpm (I'm guessing, forgot to look at tach) at which point it will pretty much clear up and continue to accelerate more normally. The roughness lasts several seconds.

After a drive I pulled plugs 1 and 3 and both looked "normal."

I need to test for symptom #3 with the vacuum advance disconnected because it could easily be timing-related. I am still pretty certain that the 1 and 2 and possibly 3 are carburetor issues.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Mr exceptional patience ! My thoughts ( 2 cents) are try higher idle setting and retest, try more advance and retest, it seems like it could be flooding a little as symptoms are similar, but we all will wait for next installment!

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

I have responded several times about a broken wire instde the insulation having been my problem for the sameissues but it never gets posted??? My was the breaker plate ground wire, maube they will post this some day so that you can check it out.

312T85Bird

What?

Did you do anything about the mufflers on backwards?

  

He checked that in the earlier posts.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

Your car starts up and runs untill A, it warms up and then ---------?

B, the chocked up exhaust will not allow the exhaust gas to exit and it kills your engine ( the same as a potato in the exhaust pipe)

C, death rays from Mars (not my favorite) Do a Google search of symptoms of a clogged catalytic converter and compare them to what you are experiencing on your Ford.

Pete

Aussiebill, it's true that if I keep my foot on the pedal (essentially raising the idle) I can keep it going. Thing is, if I raise it enough to get it to run in gear, it will really slam when I shift it from neutral, which is not good for it, nor normal. Once it gets really hot it is hard to keep it running at all, let alone getting it into gear.

312T85bird, I have seen that post several times and responded to it the first two times you posted it. I appreciate your input!

Oldcarmark, not yet. Still not sure it's necessary, but more on that in a bit.

Pete, I don't follow you on the first line of your post there. I did your google search though and read up on the symptoms.

Today's installment: Drove car in large road loop. Didn't wait for it to warm up before leaving and didn't change anything. Went straight to a 55mph road and found that there was no trouble accelerating with any amount of throttle once the engine was already above about 2200 rpm. So it seems that the acceleration issue is probably just the accelerator pump after all. It works but I guess the shot is a bit too lean for the engine to effectively make the transition at lower engine speeds. No matter, I have 2 new pumps to try.

Made it back to the driveway without stalling, parked in driveway and like I described last post took a few seconds to stall out. Started it back up and let it run in park, got under the car with a temp probe to look at the temp before and after the mufflers. I checked within 3" of the muffler case on either end, and depending on which exact spots I probed, I saw a temp difference range of 15-60*F. The outlet side usually gave a number around 185 and the inlet gave anywhere from 200 to 250. I suppose the highest number is the most valid one. The mufflers are 18" long with the intended inlet offset and the intended outlet centered, but they are installed backward to fit. It took a pretty long time but eventually it did start running worse until it made an abrupt shut-down. It became difficult to start and keep running. I had to put it on the fast idle cam to keep it running at all, and it missed a lot at first but that diminished after about 20 seconds of fast idling. At this point I wrapped my hand with a rag and held it behind each pipe. There is definitely some pressure at the tailpipe but not especially much. The pipes are 2", I'm not sure what sort of velocity I should be expecting out of them, but I made the same check on my Buick 3.3 V6 (single pipe) and it didn't seem different from the Fairlane.

So, they definitely aren't completely clogged. Maybe being backward restricts the flow enough to raise the temp at the crossover enough to cause carburetor problems. I don't know. The only way to be sure is to remove/replace them.

I didn't get to try driving with the vacuum advance disconnected this time. I get 1 trip then she's done. If the mufflers ARE restricting flow then I'm curious how much stronger the engine will feel, as it already pulls pretty hard. I really like this car. I will really, really like it when it works properly.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Made another test loop with no change in symptoms except that I noticed a little bit of missing under light load uphill, low speed. It wasn't until I returned home that I realized I had the vacuum advance disconnected, so at least we know that over-advancing has nothing to do with this.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive