Quote Originally Posted by sdieterm View Post
My SBC is running like crap. I used a timing light on each plug wire to see if one may be not working. One was not working so I fixed that one. Another was making the timing light flash faster than the rest. I got that one blinking right. I then started it and it ran pretty good. I turned it off to move the timing light out of the cab so I could time it via the marks on the crank. I turned it back on and it ran crappy again. I retested the wires and now I have 2 that make the timing light go crazy. I guess I'll have to maybe give it the spray tonight when it's dark out to see if it's arcing. Maybe get a new set of plug wires? Could something have gone wrong on the HEI unit?
I'd say before you can even start troubleshooting you need to be sure that you have a set of good (new) plugs properly gapped, a set of known good (new) spark plug wires, and the timing set against a known 0/TDC mark on your crank pulley/dampener.
With those basics covered I think I'd borrow a dial indicator and check rocker arm movement as a friend rotates the engine by hand (plugs out to make it easy) to rule out cam wear, assuming it's a flat tappet cam. Just my $0.02 and others may have better ideas.