427 dart block with 750 quick fuel, cold start trouble

[427BDR]

quick update on this thread. About 2 weeks ago my car was stuck on fast idle after I filled up at the gas station. RPMs wouldn't drop below 1700 no matter what I did. Brought it home and shut her down, restart the next day and after struggling to get it to start, noticed the fast idle was stuck on 1700 again.

After some trouble shooting I realized the fast idle screw was sticking on the fast idle cam. Now about 2-3 months ago I had adjusted the fast idle cam because the car was struggling to hold fast idle at start up. Evidently I had over adjusted it, so I turned out the fast idle screw until it was no longer holding up the cam and the high idle resolved itself. I also noticed that the past two cold starts, each taking place after car sat for 3-4 days, fired up without any smoke or stall out.

Not sure how the cold start flooding and stalling issue may have been related to a stuck fast idle screw, but will continue to monitor the colds starts to see if the issue has resolved.

[NZCOBRA]

Hi, when you cold start, have you tried not using the choke , I have never needed a choke , two pump shots and they start ok ,Just hold the engine to a fast idle on the pedal for 30 seconds and it would idle. When I did have a choke set up on a carb I found when fully closed I pulls far too much fuel into engine ,you need to increase fast idle on choke mechanism and use less choke . Cheers

[Gaz64]

Originally Posted by 427BDR

quick update on this thread. About 2 weeks ago my car was stuck on fast idle after I filled up at the gas station. RPMs wouldn't drop below 1700 no matter what I did. Brought it home and shut her down, restart the next day and after struggling to get it to start, noticed the fast idle was stuck on 1700 again.

After some trouble shooting I realized the fast idle screw was sticking on the fast idle cam. Now about 2-3 months ago I had adjusted the fast idle cam because the car was struggling to hold fast idle at start up. Evidently I had over adjusted it, so I turned out the fast idle screw until it was no longer holding up the cam and the high idle resolved itself. I also noticed that the past two cold starts, each taking place after car sat for 3-4 days, fired up without any smoke or stall out.

Not sure how the cold start flooding and stalling issue may have been related to a stuck fast idle screw, but will continue to monitor the colds starts to see if the issue has resolved.

The screw does not hold the cam.

The choke mechanism operates the fast idle cam and the screw rests on whatever step of the cam the choke is set to. So the cam may be binding on it's pivot post. The cam is weighted to come away from the screw, the tension of the choke housing spring determines the release time after start. You may have set the choke too rich at the housing adjustment. I would rather see about 1200 rpm as a fast idle. If you need a carb with choke, then the engine must be a mild street engine.

[427BDR]

Update on this thread.

So after backing off on the fast cam screw, which was causing it to stick, the car has consistently started every single time on cold start with no symptoms of flooding. Even after sitting for 2 weeks I was able to get a clean cold start without any stalling!

And since we switched over to summer blend gasoline on May 1st I no longer have any dieseling on a hot shutdown. There is still some percolating that happens after a hot shutdown but much better than with the winter blend gas. Now the question is how do I get summer blend gas come November LOL!

[vatdevil]

Ethanol Free Gas Stations

[Gaz64]

The screw is not the cause, it is the effect.

forums.holley.com/entry.php?439-How-To-Adjust-The-Electric-Choke-On-A-Holley-Four-Barrel-Carburetor

[427BDR]

Originally Posted by vatdevil

Ethanol Free Gas Stations

this is a great link, unfortunately nothing within 300 miles of SF bay area. In time there won't even be a regular gas stating in the bay area, we'll all be forced to drive Teslas LOL!