Join Date: Mar 2002
Location: Austin, TX, USA
Re: Idle hanging up with vacuum advance hooked up
Vacuum advance will raise your idle speed. That's one of the advantages of vacuum advance - the engine runs more efficiently with a bit of advance at idle. Your base idle speed should be set with the VA connected. Vacuum leaks can be exaserbated by the VA timing advance. VA increases idle vacuum slightly.
Also be sure that the mechanical advance isn't kicking in too low. You'll have to do this with a timing light and the VA disconnected. Run the throttle up and down by hand and determine where machanical advance picks up. If it's coming at at low speed (like 1000-1500 RPM) can can really foul up your idle speed and make the idle act inconsistantly.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI