750 idle question.

My 750 Holley seems to never idle well. When it's cold or in gear it idles lower where it should, but when warm and out of gear it idles way high. What causes this? How do I fix this problem?
Thank's for your time.
Mike

 

idle problem

sounds like a small vaccume leak somewhere to me what 750 and what manifold? do you have an adaptor or bolted directly? get some carb cleaner and spray around base and see if idle pick up also check all hoses and pcv good luck walt :Smarty:

 

Idle question.

I have a Holley 750 with a Edelbrock Performer intake.
The carb will be changed to a 870 Holley this week with a heat spacer plate and it should fix the problem that way.
Thank's for the help.
Mike

 

Fixed

Well it turns out the carb is fine.

Well the problem was a distributor gear and cam gear that were worn out from a high pressure pump that was on the engine causing the timing to be changed due to the ware.
The pump put excess pressure on the cam and dist. gear causing it to ware out prematurly... also I had no idea of an adjustment on the holley carbs for "in park idle" and "in gear idle."
The one is easy to get at - the other you have to shut off the engine and hold the throttle back to expose the adjusting nut.
Now you know that it was fixed and the carb was not the problem.
Thank's;
Mike

 

I didn't know there was an in park idle and in gear idle adjustment either. Got a picture?

 

A few pic's.

Here are a few pictures I made up quick.

The "Out of gear" idle adjustment is also known as the "Curb idle."
The "In gear" idle adjustment is also known as the "Fast idle speed screw."

With these properly adjusted together the differance in rpm from in gear and out of gear can be less. Usually it's a few hundred rpm differance. Mine idles at 800 rpm (big cam) and in gear idles at about 500 rpm with a real good lope.

Mike

 

Thanks Mike,

How big is your cam that it will idle in gear at 500? I won't take mine lower than 800 in gear. It's the 288-96H. If you do a search for that number, you can find a clip of it idling.

 

Ta

Hi Steve;
I have the TA-413 cam.
The reason I have it idling so low is because I have a stock convertor on my tranny, any higher and it's a bare at stop lights. It runs well that low actually.
I have an ATI 2800 stall convertor waiting to be installed in the spring.

I listened to the clip, it sounds familiar! It's real close to the way mine sounds.
I checked out a few pictures of your car and engine and it looks great. Keep up the good work!
Mike