I have a Holley 650 Double Pumper with 2-circuit idle(4777 if I recall correctly) that I want to try the 750 Main Body on from Proform. I've heard these bodies are set up for a 4 circuit idle. How would I convert to get a 4 corner idle? I have a 750 VS laying around-do you guys think I can just canabalize it and stick the primary metering block on the back of the 650DP and have a 4-corner idle?

Thanks for the help guys.

Nick

rear is a different metering block from front.
you'll have to get the right one.
all the passages would be backwards.

there is a metering block kit in either summit or Jegs for around 80 bucks

Ahhh I see. If I switch to a 4-corner idle will I have to run a Power Valve in the back too?

You can run the same jet plate front and back, infact you should because the air bleeds in the Proform body are same front / back. You can just do the ussual (power valve) plug in the rear and jet up about 6 sizes. The only problem you may have is your 650 base plate may not be set up for 4 corner idle - it has small passages runnin right around the outside of the butterflys from the front to rear idle nozzles, theses passages should be plugged in the middle (devided) so that each idle mixture screw works seperately.