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394 4GC Rochester Carb


Guest bobkat2

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Guest bobkat2

I have a 1963 Olds 88 that I converted from a 2 to 4 barrel carb. I have gone through 4 professionally rebuilt carbs. 3 were purchased through speed shops and labeled Holly remanufactured and the 4th rebuilt by Canoga carb out of CA. All of the carbs leaked through the upper (air horn) gasket. I just had a local repair shop look at the carb that I was forced to use from Canoga. They fixed the problem I had with the secondary throttle plate staying open after taking my foot of the accelerator, found that there was no secondary needle a seat in place, replaced the top gasket and the gasket that sits between the choke and carb. Those 2 gaskets are still leaking. Does anyone have an idea how to fix those leaks?

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Does the carburetor have alot of corrosion on the sealing surfaces? If its real bad its next to impossible to get it to seal.If it is corroded you might want to get a new core.

Or sometimes the kit is old and the gaskets get brittle. Make sure the rebuild kit is new and not a cheap one. If you can't rebuild it your self its difficult to say what a shop does or doesn't do.

If it were me I would start over and rebuild it again with a fresh kit. make sure everything is clean and dry and fits together good. Do NOT use any kind of sealer.

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Guest bobkat2

Hi Nick,

Thanks for that information.

This is what I can tell you about my situation. I purchased this carb on ebay as a newly rebuilt. It leaked through the areas as mentioned. A repair shop that specializes in GM performance cars took the carb completely apart and installed a new kit. They did mention the fact that they had a difficult time at removing some type of epoxy that was used along with the upper gasket.

I find it to be more than a coincident that all four carbs would leak in the same area. So far I have $475 invested in this carb and months of aggravation in dealing with rebuilts.

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Epoxy on any gasket surface on a carburetor is a BAD thing.

As far as leakage is concerned:

The gasket should not LEAK (stream of fuel), but with modern fuel it may weep slightly (just enough to leave fuel stains on the side of the bowl). This will occur when the engine is not running. You should NOT see wetness when the engine is running.

Jon

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Guest Bob Call

Nick, why don't you sent it to Jon at The Carburetor Shop and let him do a proper rebuild? It may cost a little more but only once not four times.

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Have you checked the fuel inlet pressure? Could be high enough to push past the needle seat and flood it a bit. You haven't told us whether you kept the original fuel pump, converted to electric or what.

It bothers me that you got a rebuild that was missing parts. That says a lot for the integrity of the rebuilder, though I expect the core came to them that way and the rebuilder didn't know or didn't care what was supposed to be in there. Not like 4GC parts grow on trees either.

Now, you just think the carb leaks are a pain. Have you set up your transmission throttle linkage for the 4-barrel carb? Next step is squalling because the HydraMatic is acting weird.

This is one-a them times it would probably have been better off to left things alone.

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Guest bobkat2

Thanks all for the information. The fuel pump is the original and not an electric.

I can say that the fuel is leaking when the engine is at an idol, on the right side only. And yes I have noticed a slight strange sound which seems to be omitting from the trans. in 1st gear only. However I believe that the nose fades away after the car is at the normal temp range.

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