We built a 383 LT1 for my buddys 94 formula. I ported the heads, but it has stock valves. It has about 11:1 compression, cc306 cam, 1.6 pro mag rockers, hooker long tubes into 2.5" duals through bullets, pcmforless, ect...

Well, I moved before he got it on the road(bought all new sensors, opti, and everything before running it. He says it runs strong(will break the tires loose at around 50 mph with stock stall and gears).

He said that it developed a bad miss though. all plug wires seem good. He pulled out the plugs and he said that they were black, which I would assume means it was rich. He also said that he thought it almost looked like there was slight metal deposits on the plug. The only thing that I know that will do that is detonation. He did say that when he first drove it though it still had the old(6 months- a year old fuel) 87 octane gas. He is running 93 through it since.

My question is should he try a colder plug, or just the stock ones. I figure either way, he is going to need to run it and pull plugs again to see if it looks like he is getting detonation now that he is running the 93.

Any suggestions welcome.

Thanks

Ben

 

Generally, a plug will foul more, the colder it gets. Guideline is to go one step colder for each 75-100HP you add. What plug is he running?

 

He is running the stock ac delco plugs. He just put new stock replacement ones in it, and drove it with the good gas in it now. He said it runs good and didnt hear any detonation. He is going to pull the plugs back out and check them.

Ben