Hi guys, i have a idle issue that i need some direction on. The issue is: The idle is 300-400 rpm's high after comming to a stop wile driving car normally around town, after a few seconds the idle returns to normal (650 in gear) and will idle forever at a traffic light without faults,then i take off stop at another light idle stays up around 1000 rpm's then after 10 sec drops down to 650. This issue is a new issue after replacing 350 sbc to a built 383 stroker. The ignition system,heads,intake,exhst and carb is all the same transfered to new block. Only differant component is i went to electric fuel pump and pressure regulator set up to supply enough fuel to a 650 holley dp. I thought for sure it was a carb issue so after rebuilding carb several times with same results i purchased a new 750 holley dp and had verry same issue it did not change for better or worse motor had the same high idle issue. Specs on my motor are : 383 sbc stroker 10:5:1 compression using high octain pump fuel. I have a comp cam with .050 duration spec of 230/236,roller lifters and rockers. Dart sportsman heads and intake 64cc chambers w 2.02/1.60 valves. MSD 6a ignition w-billet dist,idol vacume is 12 psi with a 1 to 2 psi variance. I have done all basic troubbleshooting and i am now looking for any help you guys can give me. thank you john

 

The electric fuel pump is totally not needed. My crate 454 with 750 demon carb is supplied just fine with a stock fuel pump. It could be your problem. It could also be a sticking weight in your distributor or simply a sticking linkage.

 

Thank you for the responce, i have tried to simulate the distributor springs and weights opening and closing by hand and it looks like they are snaping back as well as the carb linkage is closing all the way every time??.its just one of those wierd issues and probably somthing so simple that i am missing it but if anybody has any more sugestions i am willing to try anything. Thank you john

 

OMG I thought this was going to be a Religious thread.

 

If it has a vacuum advance, I would say the advance is teetering at the point of opening and cant decide where it should be. When you come down from higher RPMs the vacuum is up and you have advance. After a short IDLE the vacuum just gets under the point where the advance falls out and your IDLE speed falls.

 

Thank you sir for your responce. I do not know what religon has to do with a running problem?? But i do not have a vacume advance distributor and the problem also does not happen until after 10 min of driving. I thought it was tempereature related but the car runs under 200 degrees all the time. Thank you for your help, john

 

If you knew how to spell IDLE and not IDOL Haha... You would have got the reference to religion!