500, 472, 425, 368 Discussion, 1968 Quadrajet throttle bushings and leakdown in Cadillac Engine Technical Discussion; I've built several q-jets and I know the typical problems with worn throttle bores and well plug leakdown, but I'm ...
I've built several q-jets and I know the typical problems with worn throttle bores and well plug leakdown, but I'm about to do it again and I would like your ideas.
On the throttle bushing solution, do you recommend doing it myself using one of the kits online that come with a drill bit and brass bushings? I don't have a drill press and I don't know if I'm going to get the angle close enough.
Also regarding the bushings, I'm not even sure I have to do it. To test, I sprayed ether right on the outside of the bore while the car idled. On the driver's side, there was no effect. On the passenger side, there was a significant drop in idle. That indicates the bore is elongated on the passenger side. Agree?
And last of all on the well plugs - I've fixed them with cheap epoxy and marine epoxy and nothing holds long enough. If you've ever tapped the well plugs and fit them with a threaded plug, I'd like to hear how that went for you.
Age-old questions I know! But I've researched all the solutions and I'm not convinced on a couple of things. I want to hear from people who have tried 'em.
Automobile(s): 1977 Coupe (blue), 1977 Coupe (yellow), 1977 Coupe (green)
Re: 1968 Quadrajet throttle bushings and leakdown
Doug Roe's illustrations recommend using a drill press to repair the bores. I have seen the wells capped with brass plugs. I didn't investigate further. They appeared to be pressed in. If they used a sealer, I don't know.
I had a V8 that would idle nicely at 500 rpm. Trouble was, the idle speed kept changing. I finally found, the the butterflies didn't always close to the exact same position. The throttle bearings were worn, and sometimes things would move around and bind. A bigger problem than air leaking past bushings. Bruce Roe