Until recently I always fell for the .030 trap. What really taught me a lesson was a 15KW Kohler Gen-Set my Son bought from a Govt. auction. It actually came from Area 54 and the power plant was a 4 cylinder Yan-Mar diesel. He got it real cheap and I was now a diesel mechanic. The engine was seized and after a going over it seems water got into the cylinder that had it's valves open when it rained in the desert. I pulled the head and the cylinder wall had rust etc. Soaked it a few weeks with PB-Blaster and finally got it to stroke to BDC using a wrench. I honed with the piston still installed with an adjustable hone and the bore looked like hell, Pits, scratches. We decided to wing it and I added two new valves to the head and hand lapped them in. You see we didn't want to spend a fortune if maybe the Gen head was trash. After bleeding out the air on the injectors it fired right up. I figured by the smoke it was running on only 3 but a few minutes later the smoke went away and that engine has been fine ever since. The theory on bores goes back to that study I posted a long time ago on losses dues to ring gap and gap spacing on pistons. Bottom line is that a scratch or wide ring gap is only a small percentage compared to the square inches of the piston face.
1978 Ranchero GT 351W C6
1979 Ranchero GT 5.0 HO, AOD w/98 guts, 3.50 9" Traction-Lok
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Salt is for steaks-- Not roads!
Alcohol is for drinking-- Not in my fuel!
