anyone re bush carb base plates?

I have had this come up before; (unfortunately) my buddy's job that used to be able to do this sort of work for me dried up (downsized, bought out and shipped to Mexico; no he did not follow them there)
SO that said I have 2 Carter ThermoQuads that need their primary shafts reamed and bushings installed. and sorry I refuse to jump ship and go holley. I have a couple AFBs that I could use if need be. Anyone here able to do that sort of work?

 

Nobody with a mill and a set of reamers able to do this sort of job?

 

Just find a machine shop in your area. Less hassle.

 

Carter used a MUCH greater clearance that either Holley or Rochester. What is the shaft to body clearance as measured with a dial indicator? Have been working with TQ's since they came out and have done some with over 250,000 miles and have not yet seen one out of tolerance.

Jon.

 

oh REALLY??? I have not measured them but usually when they are loose enough to "feel the slop" they need rebushed.

 

I can do them for ya, shoot me a PM.

 

Carter used a much greater bearing surface area than the others. Tolerances of 0.016 to 0.022 are allowable on the Carter AFB, AVS, and TQ. The Carter WCFB used 0.004 to 0.006, which seems to be common on others.

Have yet to see one of the AFB, AVS, or TQ's that REQUIRED bushing.

Jon.

 

PM sent.

 

Thanks for the reply. I see that "carb king" says that theres no need; but I don't need any vac leaks at the shafts. The butterflies are still intact(swdged screws) I snapped 1 head but the screw ws turning just prior. I was able to turn them all ~3/8 of a turn before they bound so they'd need the tails "dremelled" off before taking out the butterflies. How much would you want to do this??? How long would you need?? (I DON'T need these done like over night or anything crazy like that, just so you know.) theres a green coating, I guess they coated the shafts with teflon; theres a thermo Quad specialist out of Georgia that I've E mailed back n forth with recently that says he can (and does many of them) that I asked for a shipping address about 10 days ago and still waiting. I have 2 of these torn apart and want them reassembled before parts go missing. I'm about an hr south of chicago (60901) thanks for your offer let me know. Catch ya later, Don

 

I can do them for you too,PM me.

 

Jon,
Not to question your knowlege, but I too have had several Thermoquads that have vacume leaks and visable movement on the primary shafts. If the base plates do not need bushings (which seems to solve the problem) what is the cause of the movement and vacume leak? Trying to learn something here.

Just for the record, I can change the sound of the vacume leak (whistle) by moving the shaft forwards and backwards. Gene

 

Gene - if they are out of tolerance then they would need bushing. In the thousands we have worked on, have not seen any out of tolerance; but it certainly could happen. Since the throttle bodies are aluminum and aluminum expands with heat; too close a clearance cold will cause throttle bind when hot.

A whistle could be present if the idle mixture screws are adjusted out too far (rich), thus allowing the throttle plates to completely close, even if the shaft clearance is within tolerance.

Jon.

 

Its been a long time since I took Metallurgy 101 but a hole in an aluminum casting EXPANDS at the same rate as the surrounding aluminum when heated. Since aluminum has a greater coefficient of linear expansion than steel that means as the carb heats up the shaft clearance will be even greater than when it was at ambient temp.

 

Actually, it goes the other way. The shaft clearance is greatest when cold.

Jon.

 

I have found an easier way. By cutting an o-ring groove in each end of the throttle shafts to fit an o-ring with a minor interference fit in the shaft bore, you can slide them back together with a viton o-ring in each groove and have a "forever seal" with no future wear or leakage. I have done about 25 carbs this way, and never had a problem.

Dan