I have heard anywhere from 40 to 70(believe it or not). I recently gapped mine at 50 and really don't notice any difference. I would say anywhere from 40 to 50 would be optimal. If for some reason you enjoy removing and installing plugs, do some experimenting. Maybe the guys that put there's at 70 do get a benefit from it.
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1969 fast back; yellow; weld wheels; 302 roller with GT-40 heads; 3:55 gears; 5spd T-5; MSD 6AL; E-303; flows; Hedman headers; Holley 600;
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