I have a 650 Holley DP and the idle is a little eratic. Sometimes it idles at 800rpms, sometimes 600, sometimes 1,000. I've double checked almost everything else(timing, idle screw moving, idle mixture screws, etc.) and now I'm beginning to think that the throttle bushings are leaking a little vacuum every now and then cause there is a little slop in them(carb is 7+years old).

Has anyone changed out the bushings? Is it difficult or expensive to do? Does anyone know of any kit that does it? I remmember seeing one but for the life of me I can't find it now. Thanks for the help.

Nick

 

Look in a phone book for carburetor shops. When I needed it done for a Q-Jet I found a place that advertised that they do throttle shaft bushings. I found a kit, but it costs more than what it would be for shop to do it since you have to get a special tool for it. Check here . There is a post about someone here doing it without a kit (on a Q-Jet) but you need access to a drill press. Holley's I don't think are as prone to trouble with the throttle shafts, so make sure they are bad. Try to wiggle the primary throttle shaft (up, down, fore, aft). There should be very little movement, if any. Some Holley's use some teflon strips I think as "bushings". My Holley rebuild kit had some in it, maybe that is all you would have to do. Hopefully one of the knowledgeable Holley people will be able to give more info.

 

It's been a while since I disassembled a holley but I think they have the same bushings as a q-jet. Check my post

https://www.thirdgen.org/techbb2/sho...hreadid=206860

This has saved several carbs here...

 

Good info!-Just one question- what should the thickness of the brass bushing be? It seems if it were thicker the throttle shaft would not go in and if the bushing was too thin you'd have the same problem.

 

well if you use the brass tubing pictured then you have no worries. GOt mine at the local hobby shop...