r572cobra

has anybody built a steel block,4.030 bore by 4.125 stroke,ls motor,im thinking of doing this,and was looking for pros& cons on the build,408 and 421 rotating assemblys are the same price.

r572cobra

55 inq.and nobody has a opinion.

180ls1

iTrader: (4)

hmm most people use a 402 408 or 418, im not sure why we dont see more 421's maybe it is a little out of square or something i dont know.

S10xGN

iTrader: (11)

Opinion: Don't use a 4.125" stroke as it will pull the piston too far out of the bore at BDC.

r572cobra

dont ,they build some 427,434,7440,with that stroke.

SOMbitch

iTrader: (8)

Yeah but they are not on a gen III block usually. The 427 can be done from stretching out an LS3 block and the 434/440 stuff I have seen are done on a LS7 block.

S10xGN told you why......

r572cobra

those the ls7 bloch and lsx block have longer bores,ther is a sponser on here selling a gen 3, 427 block,with the same crank.

1CAMWNDR

iTrader: (21)

I would limit it to a 4.100" stroke max, but a 4.00" stroke would be nicer. I have a 4.07" bore iron block filled with Hard Blok up to the water pump ports and a 4.100" crank. It has real nice Wiseco pistons designed specially for this stroke and it burns about a quart and a half of oil every 4,000 miles.