Need help with engine problem

[SuperNovaSS]

Is the tach still a factory mechanical tach or is it electronic? If it is electronic, I would try disconnecting it. Also, I believe you said this was GM HEI. If so, as I said before, I would swap the module or at least have it tested. Modules, coils, and pickups for HEI go out from time to time and can cause the issues you are describing.


Jason

[drdave69]

Eric, I adjusted the mixture screws to achieve the highest vacuum at around 13 - 14 inches. I printed an instruction sheet on how to set the choke and fast idle cam. I'll get to that the next time I work on it.

I put the 3" side pipes back on it and drove it a little while this evening. While it will idle when warmed up it still doesn't want to when cooled down a little and it still has a little "run on/dieseling" when turned off. I may play with the timing in 2 deg increments to see if it helps any.

Jason, the tach is the original (I assume) and it appears to be mechanical. The 502 has the factory HEI. I have replaced the coil but not the module(s) in the body. Is there a way to test it/them? As you stated would a bad module(s) cause the poor running characteristics or would it cease to run at all?

Thanks for all the help guys. Hopefully I can figure this out without having to find somewhere to take it.

[napa68]

The module controls dwell. Bad modules, while often just stop running, can cause a variety of other issues. They also too, can be heat related (heat soak)

Tim