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My engine is leaking gas where the carb meets the intake. Some told me that the carb is too big for the motor, and that I should replace it. The guy I bought it from, whom I still talk to regularly, says he had the original Holley 600 rebuilt and put back on. He also has a '63 TBird with a 390. I have a funny feeling that when he had both motors out of both cars, before I bought it, he put the TBird carb on the Cougar? Is this possible?

Another piece of the puzzle is that he put an Eddlebrock intake on the motor.
 

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If it is leaking fuel from the base gasket,......the base gasket is leaking and should be replaced. Check the flatness of the mating surfaces between carb and intake, then replace gasket. 600 cfm is a little big for a stock application on a SBF @2000 ft. elev., but not to far out of line.
 

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Sounds like the carb needs another going through - it shouldn't be leaking like that even if the base gasket is no good. The float levels are off or something is hung up inside of it. The Holley site has good info on adjusting things......if you feel you can do it. Otherwise I'd get somebody who is knowlegable enough to give it a going over
 

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Sure it's possible but I believe the stock TBirds had Autolite 4100's on them..which flowed 450 to 550 cfm if I remember correctly. 600 Holleys are good carbs, stick with the older ones and stay away from the Avenger carbs (metering block issues).
Check your floats and make sure they are set correctly...check YouTube out for tutorials on anything Holley..
 

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Is it for sure leaking where the two meet or could it be leaking out of the two shaft openings (primary and secondary) and running down to the intake. I found when completely re-building Holleys
the open plastic rings that go into the shaft's grooves can get knocked out of place when sliding the shafts back in. Then they can leak.
 
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