Hey Guys,
Any tricks on setting the idle on my Holley 750? I just got it rebuilt and first time out, I had to set the Primary Idle Screw quite a ways down to get it to idle. Anything below 1000 RPM or so and it shook and didnt like it much. I didnt mess much with the idle mixture screws in fear of jacking something up. Any clues to get her dialed in? Whats my ideal idle with the 454, in the water with the drag from the pump? I dont think I can adjust it out of the water cause its just gonna change once I splash it right? Thanks!
Chris
Sorry I'm late to the game, been pretty busy of late. You have to play with the idle speed and the mixture screws optimizing one usually makes the other one need adjustment. You use the vaccum gauge on manifold (anywhere under the throttle plates), your jet in the water. I usually tie mine to the dock so I can play without going anywhere. I think everyone mostly covered it, but at the end of the day, you want the RPM set to where you want it, pulling the highest vaccum reading. The holley book says you want the mixture screws 1.5 turns out - I find if the main jetting is correct, you want closer to .75 to 1 turns out. If it is too far open, the idle screws will have no effect, and you need to bump the secondary idle set screw a little bit to get the primary idles working. I like to have about .003 showing of the secondary transfer slot.
I personally like my idle low so it can idle out of the docks without feeling like I'm gonna hit something. My engine idles at 700 rpm with a 246 @ .050 duration cam. I have a hand throttle, so I can bump it up when cold.