main cap walk

A BB MoPar just basically does that. A friend I built a 440 for who sprays nitrous got greedy and burned a piston, so we pulled it to inspect/freshen it. It had years and many passes on it, with a midrange bobweight, and the juice flowing on it most of the time. The pistons looked great (except the one that burned) and so did the rods/rod bearings (which I reused), but the #4 main was in the copper and no longer fit snug in the block or cap. My machinist said we got extremely lucky, he gauged the main bore and it was perfect and polished the crank. We had used needle-bearing rockers, so I attributed the #4 wear to oil starvation somehow via the valvetrain oiling. I converted it to full time (lifter galley fed) rocker shaft oiling with a restrictor in the head rocker stand, and put a new set of main bearings in. There was uniform cap walk, even with ARP fasteners, so I just slammed it back together. SO far no problems with it, still blasting the laughing gas and turning the number. Another friend has a 440 in a Super Street bracket Duster that ran for years, with a Herb McCandless setup (ultra-light Venolia dykes-rings pistons, polished/lightened LY rods, bridgeported combustion chambers to clear the pistons, etc.) and he ran nothing but VP112 in it and launched with a transbrake at 5000rpm. Used ARP main studs, and STILL had cap walk (worse than the 440 I built for spray, with heavier components). I think they just do it (cap walk), but make sure you don't starve the #4 main for oil with needle bearing rockers!!!