I just changed an Edelbrock 600 for a Holley 750 DP and I cannot get it to idle down. The screw that works by the Throttle linkage doesn't have an effect. I was told this carb has 4 corner idle, whatever that means. Can anyone help me?

Matt

Is the Holley new, or did you get it from someone else used? If used, check to see if the secondaries are open at all in the idle position.
Sometime guys with big cams have a hard time getting enough out of the main idle circuit, so they will open up the secondaries a little to help get enough rpm at idle without exposing the transfer slot.
Are you using an adapter under the Holley?
Are the throttle blades possibly hanging up on the adapter?
The 4 corner idle means that there are air/fuel idle adjustments on both the primary, and secondary metering plates. These should be set using a vacuum gauge. Set the main idle first, then adjust the air/fuel mixture to achieve the highest vacuum reading. If no vacuum gauge, set them where you get the highest rpm. They should be about the same...if one is a turn & 1/2 out, the other should be about the same. Do the same thing on the secondary side.
Hope this helps graemlins/beers.gif

Got it running, seems there is a secondary idle screw in the baseplate that had to come out a bit.
Now Im trying to fine tune it. How do I make the Secondarys come on hard so that at like 40 mph I can punch it and really feel the car go?

MaTt

When the carb is setup correctly, you shouldn't feel the secondaries come in. Just a steady pull.