Spark plug question

[floppyfoot]

Have spark plug problems. The engine builder, before we purchased the car, used Autolite AR473 spark plugs and said they had to be indexed for piston clearance. Running MSD ignition, app. 12.5-1 compression, Dart Eagle heads, 4412, with Eldbrock Performer, flat top pistons. Have made several jet changes, now using #73, thses seem to work best. Trying to decide what plug gap to run. Am changing to NGK B9EFS plugs. The last set of Autolites we put in, 3 went dead at the start of the race. They just quit firing. Everything else checks out fine, just 3 dead spark plugs. No info on cam, builder will not give out that info. Engine is a 355 Chevy.

[speedbuggy]

I think that's a good move on the plugs. I used to problems always fouling Autolites. Then, switch to NGK and no more problems. I run them around .040 gap.

JMO, if my engine builder didn't tell me what my cam was, I'd get another builder.

[floppyfoot]

This engine came with the car my son bought. Two fellow racers, same class as we are, got their engines back from him last week and they both locked up last Sat. night. He has a great track with engines, I do not know what happened to thier engines yet. If I would have an engine built by someone, they had better tell me just what is inside that engine or I would go somewhere else.