1957 automatic stalling when stopping

[TJShea]

I have a 57 D code with a 312 and auto transmission. I recently had a the engine worked on (It had to be removed for what the repairs folks had to do), and a new carburetor installed. The carburetor is a Holley Classic carburetor 0-1048-2 4160 465cfm.

The car at idle runs at about 500rpm (little hard to tell for sure on the tach). However, when driving, engine warmed up, etc) when pulling up to stop at a signal light, it will slow and drop idle below the 500 rpm, and even stall. It starts right up. If I “goose” the accelerator just a little as coming to a stop the idle will pick up. Any ideas what may be causing this?

This page contains affiliate links for which I may be compensated. As an eBay Partner, and Amazon Associate I may be compensated if you make a purchase at no cost to you.

 

[64ZCODE]

The idle seems really low. You could try adjusting the idle speed to ~750-800 rpm and then adjust the idle mix.

 

[sre]

64ZCODE you're spot on with the 750 RPM's w/an automatic. Why was engine removed and what was wrong w/the carburetor that it had to be replaced?

 

[TJShea]

64ZCODE you're spot on with the 750 RPM's w/an automatic. Why was engine removed and what was wrong w/the carburetor that it had to be replaced?

The engine was removed to perform a complete engine flush. Unbelievable what came out. I think there may have been dinosaur bones. Replaced the expansion plugs as they were leaking. They found two loose in the block. Replace the head gaskets. Replaced other gaskets like pan and transmission. Repainted engine and refinished exhaust manifolds it all looks brand new. The carb was one that folks placed on these cars in the mid 70s to pass Cal emissions. That was where the car was in California. It was basically maxed out and somewhat starving the engine since we are at a much higher altitude, etc. The replacement replicates the original (or I was led to believe). The one removed was from the 70s a Holley 80457. I doubt it was touched since the 70s. I kept that carburetor. if this keeps up, i can always switch back and see what happens. But from what I have been told the newer 0-104802 4160 is a good replacement.

 

[64ZCODE]

I believe the 4160 was the carb that folks used to replace the "teapot" 4 barrel carb that was original to the 312 engine. But the 4160 comes in different cfm ratings. Make sure it's the 600 cfm version, in good condition, and hooked up properly to accelerator linkage and choke is operating correctly. See if you can adjust idle speed and mix to achieve a stable, acceptable idle, and go from there. And please keep us posted!

 

[TJShea]

Well I think I may have found my issue. It looks like I may not have a dashpot? I took some photos where I thought it might be located if I had one. Am I correct and I do not have a dashpot? And could that be the reason for the stalling when I come to a stop? Do I really need a dashpot, or can I make an idle adjustment that compensates?

 

[64ZCODE]

Not all Holly carbs have dashpots. I think that's for manual transmission applications. So yes, I would try adjusting idle and mix and see if that takes care of the issue.

 

[Tom Alpers]

Well I think I may have found my issue. It looks like I may not have a dashpot? I took some photos where I thought it might be located if I had one. Am I correct and I do not have a dashpot? And could that be the reason for the stalling when I come to a stop? Do I really need a dashpot, or can I make an idle adjustment that compensates?

If it's stalling when you slow to a stop or when you put it in gear the dashpot is unlikely to make any difference. Another problem with running it at 500 rpm is that its so slow you get zero charging from the generator and almost no water flow in the cooling system. And you are likely to get a stumble if you take off fast from a stop.

 

[cscolastico]

I have a 57 D code with a 312 and auto transmission. I recently had a the engine worked on (It had to be removed for what the repairs folks had to do), and a new carburetor installed. The carburetor is a Holley Classic carburetor 0-1048-2 4160 465cfm.

The car at idle runs at about 500rpm (little hard to tell for sure on the tach). However, when driving, engine warmed up, etc) when pulling up to stop at a signal light, it will slow and drop idle below the 500 rpm, and even stall. It starts right up. If I “goose” the accelerator just a little as coming to a stop the idle will pick up. Any ideas what may be causing this?

For what it is worth, my 57 came with an Edelbrock 1403 and has been running great for nine years. (although I did have to clean it last year after some bad gas)

 

[Pink T-Bird]

If it's stalling when you slow to a stop or when you put it in gear the dashpot is unlikely to make any difference. Another problem with running it at 500 rpm is that its so slow you get zero charging from the generator and almost no water flow in the cooling system. And you are likely to get a stumble if you take off fast from a stop.

I believe 500 rpm in drive is the factory spec, but with modern gas I have to run at 700 in drive to not stall out at a light.

 

[DispatchJoe]

I had the same problem with my 1957 car wanting to stall at a stop. I changed if from an generator to an alternator and it corrected the problem. It also idled much better.

 

[TJShea]

A couple more questions. I increased the in park idle to just under 1000. When I put it in gear, it drops to below 500. and sometimes even less and will start to stall. Could there be another issue? I am a novice when it comes to more than adjusting the idle screw on a carb. I am using the in dash tach for the RPMs. I am hoping that it is pretty close to accurate. I have not installed the a new dash pot yet. Still unsure if it is really even needed if the adjustments are right. Could there be another issue, or should I bring the in park idle up to 1000+?

 

[Pink T-Bird]

A couple more questions. I increased the in park idle to just under 1000. When I put it in gear, it drops to below 500. and sometimes even less and will start to stall. Could there be another issue? I am a novice when it comes to more than adjusting the idle screw on a carb. I am using the in dash tach for the RPMs. I am hoping that it is pretty close to accurate. I have not installed the a new dash pot yet. Still unsure if it is really even needed if the adjustments are right. Could there be another issue, or should I bring the in park idle up to 1000+?

You should not need to run the idle over 900 rpm. BUT the dash tachometer is an approximation and should not rely on it for accuracy or diagnostics in tuning the carb.
You should be able to buy an old school tach/dwell meter to give you more accurate and repeatable data.
If you are truly dropping 400 rpm when putting in drive look for other issues like vacuum leak(most likely), worn throttle linkage, timing maybe(least likely). Dash pot helps prevent stalls when going from fairly open throttle to none, like taking your foot off the gas quickly.