Idle speed

[Brenton M.]

Hello guys i need your help I've just completed a full frame off restoration on my 65 roadster, I am now trying to fine tune the engine, it runs great but I'm having trouble getting the engine to idle correctly after acceleration it will not idle down, It stay at a very fast idle
unless i disconnect the Vacuum advance hose from distributor,with the vacuum advance line disconnected it works fine, Timing has been set @ 12deg BTDC, Dwell set @ 30deg. Its a 396 /425 with a non Transistor Distributor can someone tell me whats going on.

[Timothy B.]

Re: Idle speed

Brenton,

The first thing I would check is the centrifugal advance in the distributor to make sure the springs pull it back when idling. Next, check the V/A control with a miti vac to make sure it's not leaking causing a vacuum leak.

Also, if the carburetor primary shaft was bushed the clearance could be to tight and when the carburetor gets hot the throttle gets sticky.

[Stuart F.]

Re: Idle speed

Believe it or not, there are factory/repro return throttle return springs that are not quite up to the task. I have found this true particularly with the 63's with AFB's (L-76). For a long time we were told we must have a white spring to be correct. Well, no white repro I ever bought would fit right or, even when modified, would consistently pull the throttle back to normal idle. I then went with the later thinking using a black spring from the 64 and up. They fit right (length), but still would not pull it back to idle right. I have always had to use a second light booster assist spring in order to get consistent returns to idle, and this with three different carbs I have used over the years (47 to be exact). It's not pretty, but is easily removed and replaced for shows. One of my pet peeves with my car over the years.

Stu Fox