i am having a idling problem i have a 850 dual feed holley when i first start my car it idles around 800 rpm when it warms up it climbs to about 1100-1200 rpm what i need to know is where do i find the warm idle screw i was told there is two screws to adjust the idle but i dont want to start turning screws and turn the wrong ones and mess up my air fuel mixture i am not sure where the warm idle screw is any help would be great

 

I have an edelbrock not a holley but on mine the warm idle screw is the top one and when u push back the throttle then you will reveal the fast idle screw below it which is the one for when you have chocke on/cold. set the warm idle while vehicle is warm and set the fast idle afterward when its cold so that your vehicle stays running or rpms are around 650 whichever works better for your vehicle. If all this is no help on your carb then im sure someone around here who knows more than I do will peek there head in to correct me.

Also I'm sure there is an owners manual for the carb i know edelbrock has one so try the holly website maybe and get the PDF version and read up on the procedure for tuning the idle.

 

After Al Gore invented the internet, it's absolutely amazing the info you can find:

Holley tech page:

http://www.holley.com/TechService/Library.asp

fig. no 175 in this file:

http://www.holley.com/data/TechServi...ded%20View.pdf

Almost all Holley carbs in the traditional 4 bbl layout have a rather large, obvious screw on the throttle (drivers) side of the carb. It is a simple screw, easily accessible, down by the throttle lever, that mechanically controls how far the primary butterflies are open. THAT IS your "curb idle" or "warm idle."

A few Holleys have reverse-acting idle mixture screws, but MOST have traditional screws, IE you screw them out until the idle is too rich and the idle drops, then back in for "peak RPM" and smooth idle, and on emmisions control vehicles, continue in somewhat to lean them out according to the situation.

These mixture screws on traditional Holley 4bbls are located "up on the sides" of the metering block(s) as opposed to down under the front of the carb as many many OEM carbs such as AVS, Quadrajet, and a whole zoo of various OEM 2 bbl carbs were built. (fig no 114 in the file posted above)

The fast idle was traditionally over on the passenger side, and mechanically acts on the fast idle cam.