If you have a Rochester carburetor (and the likelihood is very high that you do), the super-rich running will be from a stuck power piston. There are lots of articles about that here (many I've written). When the piston fails it sticks in the "down" position and this leaves the power valve open (a simple spring-loaded ball) allowing a lot more fuel to enter the manifold. Time will never fix this...you have to disassemble and clean very well.
If you're fortunate enough to have a Carter carburetor, the super-rich condition will be from a failed diaphragm (accelerator pump diaphragm some will call it). If it has failed, vacuum will suck gas straight out of the float bowl and in to the manifold. I've written about that too, but we're not currently adding to tech tips so it won't be there.
Please let me know if you want me to resurrect any of the old carburetor articles for you.
Hi Jon, thanks for the reply.
Yes I have a Rochester. I fully rebuilt the carb. I read quite a few articles including one on the stuck power piston. It was indeed stuck in there. I didn't need to use heat, I was able to squirt some penetrating oil in there and it came free with a little force. It moves up and down freely now from what I can tell. The power piston is vacuum controlled correct? If I have a vacuum leak, which I am certainly leaning towards, would this cause rich running symptoms? I believe I have a vacuum leak somewhere between the manifold and wiper motor. It looks a little suspect to me.
