Having some issues finding the cause of a weak spark condition. Plugs are firing with a yellow spark, not blue like they should. This is on a stock small cap HEI setup. Plugs are gapped at .035, replaced plug wires with new ones recently (old wires had some cuts), cap and rotor are in good shape, pulled the ICM off and cleaned the metal contact underneath it. It went back on with some dielectric grease. I've checked at night for arcing on a couple of occassions, and didn't see anything. Car has a new coil on it at the moment.

I've looked through the GM service manuals, but couldn't find any mention of spark strength. The only references to spark I found have all been about testing if spark is present.

Anyone has any input on where to go from here?

 

Only thing I can think of is to check to see if you're getting full voltage to the coil. Usually when a module goes, it goes all at once. Curious to see how this turns out.