i want to apologize to wilbur46 because i really had not intended to hijack his thread. i hope all of this is some use to him as well. thanks to all of you for your replies and your insight. i have been thinking about this concept for well over a year now, and it's still a ways from reality. i'm taking panic's advice to heart a bit. i will reduce my proposed stroke to 4.1875, deck the block to 11.004 and build a 300 incher to avoid having to weld the crankpins, but i will stand by my concept that a long-rod, short-piston-skirt longblock with somewhat reduced rod bearing surface area (less friction), a favorable rod/stroke ratio (1.81), and a modern lightweight piston with a low-friction ring package can only stand to improve durability over a stock 302 bottom end. we all know the tall, heavy piston dillemma. as far as cam clearance goes, the big end is smaller than the gmc and with deciding to limit stroke to 4.1875, its centerline will be moved only 0.09375 closer to the cam. it has to be close to a wash between the two. only a mockup will prove it out.
the cost of offset grinding the crank would be cheaper for me than to purchase a $700-$900 302 core which i do not have.
i'm shooting for around 12.25 compression with flat-top pistons by filling the chambers to 64cc's, mostly on the sparkplug side, and using extended tip plugs to reduce the cartridge-fire issue. i will try to emulate the early pontiac v8 as a model for the combustion chamber. i'm planning on building a dual-quad intake for rochester 4gc carbs, and plan to run e-85 for fuel
cam specs will be: flat tappet, 242/252 duration at .053", .316"/.316" lift at lobe (.445"/.445" calculated with a 1.41 rocker ratio), intake opens 21 deg ATDC, closes 41 deg ABDC, exhaust opens 48 deg BBDC, closes 24 deg BTDC, 100/102 installed centerlines, lash .018"/.018" i plan on using EMPI 31mm vw type 1 mushroom tappets with bronze sleeves pressed into the lifter bores, Manton 3/8 pushrods, second-hand sbc titanium retainers (they show up on e-bay frequently and pretty cheap) with buick 455 valvesprings, pontiac 350 intake valves cut down to 1.94 and pontiac 455 exhaust valves used as-is. i will make my own rockershafts and girdles for them. ignition will be a stock delco dizzy converted to dual point with a dyna-flyte kit, mallory voltmaster coil, and an msd-6
i also have an aluminum flywheel and will use the new BHJ 235/261 balancer
