General Category > Quadrajet Carb Talk and Tips

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Michael9040:
I rebuilt this carb about 18 months ago but didn't put fuel in it until the first start up which was last Saturday.  Overnight the fuel level in the bowl dropped dramatically, yet I see no signs of the leaking well plugs (which I thought were OK by this production anyway.)  Upon shut off, I see vapors coming from the primary side so I suspected the float level.  After removing the carb, I find a high build up of black soot along the carb heating groove and also where the primary well plugs are.  Total run time was 23 minutes and it doesn't like to idle.  So, what is the likely cause of this rich condition?

Cliff Ruggles:
Sounds like you may be using an early intake with the exhaust channel in the front?....Cliff

Michael9040:
It is a correct '67 427 intake, but I did utilize the metal block off plates...........we don't need carb heat in S FL!

Cliff Ruggles:
I don't think a week goes by in the shop that we don't get a call about the early intakes with the heat crossover passage. 

I recomend blocking off the small holes at each end of the channel, to keep the hot exhaust gasses away from the carburetor.  The correct gaskets still have to be used, or there will be a BIG vacuum leak on the drivers side of the carb at the "channel".

An even better fix is to fill that end of the channel with nickle cast iron weld, and machine the flange flat.  Then the later gaskets can be used.

Another less intrusive option is to make a thicker plate the mirror image of the factory thin steel shim.  Use the correct gasket under it, then any gasket that you want on top of it.....Cliff

Michael9040:
Cliff, thanks for the replies.  So then, you evidently think that the problem is boiling fuel so I will work on that.  But you don't think it likely that there are any bowl leaks?  I am going to lower the float level as it is not a race car.

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