I lost 4 or 5, but under Heavy duty situations. Had a 56 Chevy 2 door wagon, with a standard bore 327, 11.5 to 1 pistons, the optional Z-28 solid lifter cam, tunnel ram with 2 600 holleys,(@Paladin ) munice, and 5.13 posi gears, 9.00x15 wrinkle walls Zinged it to 7500 consistently, ran mid to...