High idle in proform carb

[vanman03]

I have a 1974 Challenger with (340) air gap intake with a 650 proform cab. The car starts and run perfect at first however once I've been driving the car for 20 min my car gets a High idle in stop and go traffic?? If i turn off the car and start it again the high idle will temporarily go away but comes back. Any ideas?

https://www.proformparts.com/produc...50_CFM_b_MECHANICAL_SECONDARY/category_id/182

 

[Adam]

Is the choke opening all the way up, when warm?

Perhaps the idle is set too high and the choke is not closing when cold? That is, if you turn down the idle when warm, will it start when cold?

Is the linkage holding it open?

Is the throttle return spring strong enough?

Is the float set too high, causing excess gas to get past the needle & seat?

Needle & seat damaged by gas with Ethanol? (Costco gas) internal leakage.

 

[moparleo]

Is this a new problem ? A recent part changed ? Just a little more info please. Vacuum leak test, start car. Remove air cleaner, with your hands, try to block off the air going into the carb by covering the airhorn with your hands. If the idle speeds up, you have a vacuum leak somewhere. If the engine just dies, we have another problem. Lets keep it simple. Guaranty it is a minor problem.

 

[vanman03]

The problem turned out to be a bad Fast Idle cam on the choke. I replaced it and problem solved!

http://www.oreillyauto.com/site/c/d....oap?ck=Search_N1073_-1_-1&pt=N1073&ppt=C0261

 

[moparleo]

Usually most problems are very simple.