Tuning a Holley 800 mech sec
07-07-2003, 04:18 PM
#31
Registered
Drilling Throttle Plates
F302,
Dennis Moore says start at 1/16" and work your way up. If you drill the hole too big on the first shot, you won't be able to lower your idle speed enough. I've got some fairly long duration flat hydraulic cams that I had ground by Cam Motion. That's where my idle problem began. Only problem is I like the Q-jets and I'm trying to keep from spending another grand on carbs. My holes wound up pretty large though. I have to get my neutral idle to about 1000-1100 to keep my in-gear idle decent. May even have to disable my advance curve in the ignition and lock it in at a higher base.
As far as location on a Holley, I'm not sure. On the Q-jets, you drill them on the primary throttle plates in between the throttle shaft and the idle mixture adjustment screws. I wouldn't think it's too critical. You're just trying to get more air into the engine without cracking the throttle open so much as to engage the main fuel circuit. As soon as you uncover the transition slots in the throttle bore, your idle adjustment screws become useless.
Dennis Moore says start at 1/16" and work your way up. If you drill the hole too big on the first shot, you won't be able to lower your idle speed enough. I've got some fairly long duration flat hydraulic cams that I had ground by Cam Motion. That's where my idle problem began. Only problem is I like the Q-jets and I'm trying to keep from spending another grand on carbs. My holes wound up pretty large though. I have to get my neutral idle to about 1000-1100 to keep my in-gear idle decent. May even have to disable my advance curve in the ignition and lock it in at a higher base.
As far as location on a Holley, I'm not sure. On the Q-jets, you drill them on the primary throttle plates in between the throttle shaft and the idle mixture adjustment screws. I wouldn't think it's too critical. You're just trying to get more air into the engine without cracking the throttle open so much as to engage the main fuel circuit. As soon as you uncover the transition slots in the throttle bore, your idle adjustment screws become useless.
