running rough

[gtaa9]

I tried both ways with the vacuum advance(in the back of the carb were main vacuum is and the left front of the carb were the ported vacuum is)there was know change either way.I mentioned this before I noticest two black marks on my garage floor from my tail pipes.Does this mean that the carb is running to rich?

[booklearner]

Hi Gtaa:

It sounds like there is too much fuel, does your carb have an adjustable accelerator pump circuit? If it does, try adjusting it so there is not such a strong shot of gas being injected into the carb when you "step on it". Also, just so I am clear, the choke has come off during these tests, correct?

Fooling with the accelerator pump circuit can be tricky, it sometimes takes a bit of experimentation to get it right.

KurtS:

"....Vacuum advance has absolutely nothing to do with total timing or performance, as when the throttle is opened, manifold vacuum drops essentially to zero, and the vacuum advance drops out entirely; it has no part in the "total timing" equation...."

I am pretty sure this is wrong. Any car I've ever looked at needed some mainfold vacuum to run (even at WOT). I think that connecting to the mainifold source is an old hot-rodders trick to get snappy bottom end, but it's not the way to set it up for all around good driving IMHO. Not only that, but I suspect it's not a good thing to put 25 inches plus of vacuum on a vacuum advance designed to see only 10 or 15 inches of vacuum (mercury)

-BL