Originally Posted by IgnitionMan
.090 shaft clearance between shaft and base plate??? .009 possibly.
One of my precious jobs was working qt Holley, bandsawing Holley Dominators in half and wideneing them for Pro-Stock racers. The most successful ones used teflon bushings in that areas, NOT a sloid metal one.
What I have found on Q-jets is, the actual "bushing to shaft" interface area is quite small, and inwards towords the sidewalls if the throttle bores. When the base plate wears, there is a larger than the bushing diameter area on both sides of the throttle shaft, that have not been damaged.
Whenever I do a Q-jet baseplate, I find that the larger areas in the base plate, and the shaft have NOT been touched by the wear. What I do is cut srtips of .014 teflon to fit the bored areas of the baseplate. I have measured bouches of Q-jet baseplates and found that htis large bore area to shaft is .030 overall, .015 per "side". It is simple to insert the teflon into the unworn area between plate and shaft.
I use new throttle plate screws as well, button head Allen screws, staked and Lock-tite'd into place.
I find the solid bushings need way too much clearance to not bind when the carb is torqued down to its proper 60 inch pound torque, that is 5 foot pounds of bolt to manifold torque, not the usual impact wrench to 200 foot pounds torque I usually see on one of those carbs. The solid bushings still leak after install, but the teflon doesn't leak nearly at all, and the throttle action is one heck of a lot smoother.
I was pointed in the direction of this post #9 by someone from another forum (ray_mcavoy from the 67-72chevytrucks.com forum).
Do you have any pictures of these teflon bushing you did?
I am having a probmem with my Quadrajet, that the throttle does not return all the way, when the engine is warm and running. It DOES return when the engine is cold and off...I already checked fast idle cam, throttle cable etc....just didnt take the carb of yet to check for any other obstructions. Bet then I would need t check it without the engine running...and since it returns just fine without the engine running...it would be very hard to find wat is causing it..
so I guess these teflon mod would help, but also any advise would be greatly welcome
(sorry for my english, I am Dutch)...