Timing issues

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?

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Originally Posted by sdieterm

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?

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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.

Anytime you have the timing light flashing "faster" (your term) than the rest, my brain says distributor cap is cross arcing inside. Look inside the cap and check for carbon tracking / cracks or flash over. These issues could've been caused by the failure of a wire(s).

Welcome to CHR!

I’m making an assumption this is a stock SBC – if so, this steps below take care of 75% of all “run-like-crap” issues on an otherwise healthy engine. As others have already suggested, it’s time for a basic tune up.
• New distributor cap
• New rotor
• New sparkplug wires
• New sparkplugs
• OPTIONAL – new HEI module for “peace of mind” as they rarely go bad. Adds $30-$40.

Check for disconnected or broken vacuum hoses – and reconnect/replace as necessary.

Also assuming you have not moved the distributor, you should be able to install the above components and in all likelihood, resolve your issue(s). I know this may sound basic, but take your time with the replacement of the plug wires and go one at a time.

Firing order is: 1-8-4-3-6-5-7-2. If you get that out of sequence it will run really bad.

Once the above is completed, put your timing light on #1 (with the vacuum advance disconnected and plugged) and set base timing at 8 degrees.

Good luck and let us know how this goes!
Glenn

Wow, Thanks for the quick responses people. I say people because I once said guys and was reprimanded by a very smart and helpful woman. So; I will try a new set of wires. I'll give you the whole story of the car (if anyone cares) and issue when I get it running again. Will keep you posted.