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Discussion Starter #7
his old motor before it blew up was a 383, untouched AFR's, custom hydraulic cam, 11.7:1 compression all on 93...motor always ran rich and it had 3933's in it i wonder if they were even to rich for his old motor as well even though that thing ran well...
 

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You guy's may laugh at me , but I'd run plain old Autolites, #3924. I have ran them for years, seem to resist fouling better than any race plug, for me anyway. I have plain 3933 autolites in my car now. I have 14 to 1 and shift at 8500 to 8800, never skipped a beat..
 

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I run NGK 7's in my 11x head 13.2 to 1 427 and in the 14 to 1 447 SB2 head engine in my brothers Vette, 8's in my 461 SB2. Too often guy run way too cold on their plugs, I was guilty of it in the past. If it was me I would start withthe FR5's or equivalent, drop the total timing down around 3 degrees and work back up as the engine needs and READ the plugs.
 

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Discussion Starter #13
i was looking at the chart but was not sure which way it read from cold to hot on certain part numbers. what is the part number for the fr5 plugs and can you get that at a parts store? thanks guys
 

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Tell them NGK FR5 they will cross it. Then ajust timing and fuel to it dont just throw it in and go
 
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