Street Avenger - Rich Problem

[bigben5054]

Hello. I have an older model 670 Street Avenger on a 350 SBC. I recently rebuilt the carb. In case it matters, the engine has a mild cam, flat tops, Vortec heads, and an aluminum dual-plane intake. Current problem is that cylinders #1, #7, #2 & #4 are horribly rich. All those cylinders are on the driver's side plane, so something is causing excess fuel to dump on that side. Idle mixtures screws are both 1.5 turns out. How should I go about diagnosing this problem? Thanks in advance.

[Gaz64]

Are you sure of 1, 7, 2 & 4?
1, 7, 4 & 6 would be one plane.
Did you blast the airbleeds clear with a carb cleaner then compressed air? Gary

[bigben5054]

That's a good question. I just checked again. It's #1, #7 & #4 for sure. #6 looks fine. #2 looks a little sooty, worse than #6 but better than #4. I've looked down the carb with the engine running. Can't see any fuel at idle and when I open it up it seems to squirt fuel down both sides about the same. I sprayed carb cleaner all around the base of the carb looking for vacuum leaks and did not notice anything. I also have a backfire out the exhaust when the engine is under a load, or at higher rev (2500-3000 RPM) when not under a load. I hit the air bleeds with carb cleaner, but not compressed air. Will give that a try and report back. Thanks.

[Gaz64]

Unlikely to be carburetor related, since 1, 4, 6 & 7 are one side, and 2, 3, 5 & 8 is the other side. You have 1, 4 & 7, from one side and two from the other side. If all other cylinders are fine, you should conduct a compression and leak-down test, and go over the ignition system. Gary