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Leaking Rochester 4b carb - 74' maro


iliketoparty
10-28-2009, 09:49 PM
Okay, heres the deal, I have a 74' camaro that is my daily driver, on my way to class, it was running fine until I came to a red light, upon stopping, the car started chugging and was about to diesel out, quickly I put it into neutral and kept it alive.

So, Got it home and the carb appeared to be leaking gas and smoke coming from the primaries. I'm not very tech savy with this carb, but i do know its been rebuilt numerous times.

(leaking from accelerator pump)

http://i811.photobucket.com/albums/zz38/deathfromanal/CarbFrontside.jpg
http://i811.photobucket.com/albums/zz38/deathfromanal/IntakeSide.jpg
http://i811.photobucket.com/albums/zz38/deathfromanal/IntakeotherSide.jpg
http://i811.photobucket.com/albums/zz38/deathfromanal/Intake.jpg

Thanks in advance!

MrPbody
10-29-2009, 07:46 AM
The "smoke" is really vaporized gas.

If it's pouring fuel out the vent tube into the primary, the needle & seat or float or both, have failed.

Cliff Ruggles (Cliff's High Performance, Mt. Vernon, Ohio) has an excellent book available for rebuilding and modifying the Q-Jet. Though it's mostly "aimed" at the Pontiac crowd, everything applies to the Chevy as well. He has NHRA SS Firebird customers running 9.0s (at LEAST 700 HP) with the Q-Jet. Don't underestimate its potential!

Jim

iroc343
10-31-2009, 07:19 AM
Sounds like a flooding condition. Could be caused by many things, but the fact that it was running okay prior to this gives us some clues. First thing is it may have got something caught in the needle and seat. If you can get it started, the first thing I'd try is rev it up to about 2500 - 3000 rpms and take a shop rag and quickly cover the primary side, not letting the engine die. This may cause whatever is in the needle and seat to dislodge. Try it a couple times. If that doesn't fix it I would check the float. These had problems with the plastic floats becoming saturated with fuel and sinking causing the carb to flood with fuel. You cannot dry them out you must replace the float. They used to make a float scale to check for this. I believe somebody even makes a brass replacement that would be the best fix. Good luck and post back what you find.

MrPbody
10-31-2009, 08:45 AM
Borg Warner and NAPA supply "brass" floats.

Jim

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