I would like to know the proper procedure for adjusting idle mixture on a Holley with 4-corner idle. Having just got my new vacuum gauge, I found that front left and both rear were fully closed! Fiddling around a bit brought vacuum at idle up from about 11" to 14", with a steadier reading.

Engine is Chevy 454 and cam is hydraulic roller of 218/226 at .050" with LC of 112 deg and mid-.500" lift. Carb is a Chuck Nuytten massaged Holley 750 double pumper which flows up to 890 cfm.

What should be my starting point with idle mixture screws? I thought both front screws should be about evenly open. Should I touch the rears or leave them closed? What do they do?

Thanks guys, Chris