Catman58

This might be a dumb question but why was the spark plug gap changed from .060 to .040 ? Thanks

vettenuts

It was because GM moved from Platinum to Iridium spark plugs. The newer plugs are gapped to 0.040".

RedZMonte

Also increases service life on the plug, Larger gaps should in theory make better combustion but im running Irridium Delco's with GMPP wire and have no complaints.

S

Daddy o

So what do you do the next time you change the plugs and there's old gunked up and dried neverseize in the head threads. Surely if you use a thread chaser some is going in the Cyl. For 60+ years of "go fast" cars, they all had steel heads. Good socket and ratchet was all you needed. My vett is first aluminum head "go fast" and want to avoid an issue. Not to make a plug change a big deal, but seems to be a conundrum over yea or neah. Plugs and wires only have 25,000 on them (original) and car runs fine, but due for new ones after 15+ years. A testament to GM. Great car platform and now 15 years later I'm finally replacing parts not because they are bad, but because they are well beyond their life expectancy. Still have the iron blocks in the barn, but drive them a lot less than the vette. Always worry some A hole in a beat up p - up plows into them. None are DD cars as you can tell by the mileage.