I've been swapping a TPI 406 into a 93 Caprice wagon.

Afters many issues the latest seems spark related. I have yet to fire up the new engine.So far I've found a ground wire I never attached, a torn upper plenum gasket,(air leak) and what seems to be a poor spark, unsure of cause.

We've been trying to get a base timing set, but have been unable to. I have an induction timing light. We were wondering if the light was bad, as we haven't been able to get a good flash,(nonexistent) on the new engine. We tested the light on my wife's car to make sure it wasn't a bad light. The light worked fine. Although I can get a good bright flash on hers, I get nothing on mine.

We pulled the #1 spark plug wire, grabbed a spare plug, grounded it and cranked it over, Got a dull yellow spark, not the bright blue/white I'd expect. Tested the coil with the multimeter per the FSM, and it was well within parameters. It only has 3k miles on it, so I wasn't expecting it to be bad, and it diesn't seem to be per the multimeter tests.. Spark plug wires are new Accel 8mm.

So it seems there is something causing a poor spark, so poor it won't even fire the timing light.

I could throw a new coil on again, but don't want to throw good money away. I'll check the cap and rotor first. They could be messed up from last years issues. It could actually be a bad coil. It could be a wire crimp that has loosened up. I'll need to back track the circuit and connectors.


If any of you have other suggestions, as to what to look for, or suspicions of cause, I'll be happy to listen.