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Discussion Starter #1
Hi folks,

Need help in figuring out where's the cause for this leakage. I'm not sure if it's coming from the carburetor body or from some (bad) gasket. The engine was painted and the carb restored about 1,5 years ago using all new gaskets. Looking at the pic you can see the liquid (gas) accumulated around a bolt of the intake and peeling off the paint in its way. Just don't want to re-gasket :sad: the carb without knowing the true cause of this. Carb is a factory '67 rochester 2bbl (2GV). Any guess are welcome!
 

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There are two sources of a leak in a Rochester QuadraJet. The first is common to all carburetors. That is gas leaking out from around the brass bushing in the base plate that allows the throttle shaft to rotate.

In the bottom of a Rochester QuadraJet there is a Welch plug that seals the bottom of the fuel bowl. With heat cycling this plug can work loose, and cause a leak. The only cure is to nock out the Welch plug and tap it for a pipe plug that has epoxy sealant on the threads to hold it in place and seal the bowl.

Big Dave
 

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I second the throttle shaft leaking. Very common problem.
 

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Going to be a result of worn throttle shafts.

The 2GC (unless you have a divorced choke) carb has probably already seen nearly a hundred thousand miles before it was pulled by the bone yard and sold to a carb rebuilder (a lower mileage carb would have been sold with the complete engine as running motor). The carb rebuilder should have micrometered the shaft; or at least given it a good visual inspection for excess wear before attempting a rebuild.

If not new carb bushings won't help to seal it up unless you buy a piece of solid brass rod then turn it down to fit in the base plate. The throttle shaft would also have to be turned down in a lathe. You would then bore a new hole in the bushing you just made to fit it onto the new smooth throttle shaft with no more than three to five thousandths of an inch clearance.

Big Dave
 

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Discussion Starter #8
Still about this subject, (perhaps a crazy idea but...):D I was wondering if I could install ball bearings into the base plate channels instead using bushing to recover the sealing between the throttle shaft and the base body, of course supposing I could find BBs in exact size to fit them in.

Then, I could make a throttle shaft made of iron or even steel which also fits exactly without any gap.

The ball bearing (sealed ones) would avoid any gas flowing out through the shaft. If it work out, I would have this issue solved at least for a long time.

What do you think, guys?
 

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Still about this subject, (perhaps a crazy idea but...):D I was wondering if I could install ball bearings into the base plate channels instead using bushing to recover the sealing between the throttle shaft and the base body, of course supposing I could find BBs in exact size to fit them in.

Then, I could make a throttle shaft made of iron or even steel which also fits exactly without any gap.

The ball bearing (sealed ones) would avoid any gas flowing out through the shaft. If it work out, I would have this issue solved at least for a long time.

What do you think, guys?
Be a lot easier to make the bushings out of nylon plastic. It is self lubricating, would swell up as it got hot, sealing the shaft, and work great until it finally wore out. Then you stick in your next set of machined nylon bushings.

Big Dave
 

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Discussion Starter #10
Be a lot easier to make the bushings out of nylon plastic. It is self lubricating, would swell up as it got hot, sealing the shaft, and work great until it finally wore out. Then you stick in your next set of machined nylon bushings.

Big Dave

Big Dave
Definetely a good, simple, cheap and practical idea...lets consider this one also.:yes:. What's your opinion about mine anyway, Dave? Do you think it is "doable"?
 

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Engineers are all romantics at heart. We believe in kissing everything we do.

KISS is also known as Keep It Simple Stupid.

Never use ball bearings and a seal when a simple bushing will do. It keeps cost down and is more reliable in the long run. When your car was new plastics where just being invented. their overall properties were unknown. Designer plastics created to fill a nich market was undreamed of (not even on the science fiction radar).

Big Dave
 
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