Reply to "Piston help"

Forged pistons are stronger but use more bore clearance- up to 0.005" while cast pistons of any variety typically use 0.0018-0.0025". This makes forged pistons rattle for about a minute when first starting, but solid lifter (or some fast-bleed hydraulic) cams make about the same noise- only audible at idle. That extra bore clearance for forged pistons can save a block sometimes: you check the bores and if the wear or scratches are only .005 or less, one need not bore the block. Instead, you HONE it 0.004 or 0.005-over, install STANDARD bore forged pistons and std bore moly-rings, and gain a stronger piston, a stronger, thicker cylinder wall and lower rebuild costs. The erosion wear-ring at the very top of a bore need not be complely bored away to adequately rebuild a non-race engine. It's above the travel of the rings and has little influence on a motor's performance, beyond a very slight decrease in compression ratio. I built our last 351-C this way in 1991 and it's still going strong, with no smoke.