I have a 70 chevelle with a 396bb... bought a edelbrock 750 carb to go with it... I let the car sit for about 3 months before i had a chance to really work on it. When i first fired up the car with the new carb, only half of the carb is delivering fuel. It appears that the other side of the carb is clogged or something. I took it off the manifold, and cleaned the hell out of it with carb cleaner... put it b ack on, but to no avail. It is only firing one side. Is my carb just jacked up? Anyone have a clue? I'd appreciate some help...

Was the carb new or used? And what is your level of expertise? You may have to pop the top off the carb and take a peek at the jets at the bottom of the float bowl to make sure there's no trash in them.

The carb is new... and I did take the top off. I took the entire thing apart basically. I know enough about carbs to get by. By Brother knows a lot more, but even he can't figure it out. There isnt' any trash in the carb at all..

Let's move on to the ignition system for now. I'd pull the plugs and inspect them, and make sure to look under the distributor cap for moisture or cracks. It wouldn't hurt to check closely for vacuum leaks also. Do this and get back with us.

Also you need to set the float's front and back first,with it running.Set air mixture to ,for highest vacume then out 1 and a half turns I think.

"I'm not good at carb.'s either :D "Had mine down a month becase of :eek:

I adjusted the floats.. I started by closing them all the way, and then waiting for the engine to start dying, and then I opened them up enough to allow the engine to idle smoothly. Thats just the way I was taught, dont know if its the right way. I checked the vacuum lines, and the distributor cap for cracks, but I could not find any.

Would cracks in the distributor or the ignition system even be responsible for half of the carb not operating correctly?

OK, let's step through this one at a time...

I'm no carb guru but I don't think you are setting the floats right...your method sounds more like the idle speed adjustment. The floats should be set so maintain a certain level in the fuel bowl, not just let the car idle.

Second, you say only half of the carb delivering fuel...which half? Front, back, right, left, two diagonal barrels? The secondaries may not deliver fuel when you are just setting idling or reving in the driveway. Also, the accellerator pumps on the 750 only squirt fuel into 2 barrels (I think) is that maybe what you are seeing?

Lastly, you say the engine is only firing on one side? I don't think that one side of the carb directly relates to one side of the engine unless you have some different intake manifold than I can picture? I have to agree with the others here...double check the wiring order, pull a couple of plugs and see what they look like.

Good Luck

Originally posted by NoiD*Dog*:

Would cracks in the distributor or the ignition system even be responsible for half of the carb not operating correctly? It would not cause carb problems, but it could prevent some of the plugs from firing. But since there are no cracks, this is not an issue.

Have you done a compression check yet?

No, i haven't done a compression check. But i checked the plugs and they all look like are fine and firing.

The jet that is delivering fuel from the carb is the front left one if you are looking at the carb from the front of the car. When I rev the engine up from the carb, the secondary jet for that side.. the left side, sprays fuel. But the right side of the carb does not spray fuel from either jet, regardless of throttle position.

Is this a q-jet style carb, or an AFB? It sounds like you have isolated the problem to the carb's internals. If this is a q-jet style carb, you'll probably need to pop the top off one more time. Get some carb cleaner and use that little plastic tube to spray into every orofice and hole you see, especially at the mating surface of the float bowl and bowl cover. Be careful when you do this. WEAR EYE AND FACE PROTECTION!!!!!!!!!!! Quite often, when you spray down into one of those orofices, it comes out somewhere else, and it's usually right in your eyes!! Keep spraying until you get cleaner to come out through the main jet in the bottom of the float well. You may even have to unscrew the jet out of the carb body. There is a restriction somewhere, given your description.

Randy's advice on re-cleaning is the ticket. I had similar problems with a Holley after it sat for a long time. Even spraying carb cleaner may not be sufficient for some small passages in the carb. I had to use several (about 3) strands of fine COPPER wire twisted into one, to pass through the idle fuel passages in the throttle body to clear gum from these.