Refurbed my carbs, mounted them, and fired them up tonight. The Rocket runs good and real strong but I can't seem to adjust my idle low enough. It's not too terribly high, but could go lower. The floats are set to spec. (no flooding), idle mix screws on center carb set at 1.5 turns out, and fuel pressure at 2.7 psi. I have slack in my throttle cable and my choke is wide open. I can turn the idle speed screw right off the hi-idle cam and the idle speed will not go low enough. Motor timing set. These are a good matched set and totally rebuilt. Any thoughts on what I may have missed or what I can look for?
Did you check the bases of your end carbs so that there is as little light getting around the butterflies as possible when you had em apart?
What he said, the butterflies need to be fully closed with little or no light shining through. Make sure the other carbs are also fully closed at idle.
Don't remember what it is called, but there is a compound you can use to seal around the butterflies to prevent leaks. It was used on the original tri-power Pontiacs and 66 Olds carbs. One of the major rebuilders used to sell it.
Butterflies are tight. All brand new thick plates and lapped into honed bores. Absolutley no light leaking around them when I checked them before putting them on. Reminds me though to check end to end carb linkage rod to make sure it is not holding one open.
Take the linkage off the carbs one at a time. That might tell which one is leaking air, if that is the problem. Try running the motor without any linkage and see if it still is having the problem.
When troubleshooting a Tri-Power it's a good idea to remove both end carbs and put block-off plates on the intake. This eliminates the end carbs and allows you to tune the idle mixture using the center carb only. If removing the end carbs solves your issues then you can then look into the end carbs further.
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