Allright, so I've been fiddling on the topside of my motor and keep running into an issue. For some reason or another the passengers side bank of my motor is running very lean, but the drivers side is running perfectly. The carb is an Autolite 4300.

It started off that the motor was lean surging at idle, so i adjusted the idle screws. Adjusting the driver's screw helped, but no matter how I adjusted the passenger's screw it wouldn't change anything.

I went looking for vacuum leaks and found I had a loose vacuum plug on the passengers side of the manifold, so i got it all sealed and started the motor back up. It was still acting lean, but not nearly as badly so I adjusted the mixture screws and got it to smooth right out, but there was still an occasional pop through the exhaust.

I let it idle awhile, then pulled the plugs again. Again, the drivers bank is perfect, but the passengers bank was still running lean (but not nearly as badly as it had been).

The issue that I'm running into is on the passengers side the adjustment goes straight from too lean by plug reading and exhaust popping to too rich by what's coming out of the tailpipe. There doesn't seem to be anything in between.

Is there anything else on the 4300 that controls idle mix, or could this be connected to some other issue?

Justin

 

Hrm. Dont know on this one. I'd say a carburetor rebuild is in order, but I assume you've already done that. It sounds like there's something plugging up the works somewhere on the passenger side. I'd get a Holley 600 and be done with it, but I can understand trying to get that one working.

Thinking out loud here... power valve maybe? I know that would probably cause different symptoms, but it's a thought.

 

power valve would be rich all over. I rebuilt the carb about a year ago for my T-Bird, but it has sat for a while. May just need to get in there and clean it all out since it hasn't been used in about 6 months.

Justin