[richtazz]

Actually, the 262, 265, 283, 305 and 400 blocks are different from all the others. All factory displacement smallblocks use a 4" bore except the ones mentioned above. The 400 has such a big bore (4.125"), that they had to remove the coolant passages from between the cylinders. It is commonly referred to as a "siamesed" block and is easily identified by the lack of the center freeze plug on the side of the block. It also has such a long throw crank, that it couldn't be internally balanced. The Harmonic balancer and flywheel have counterweights for the extra balance needed. The 305 engine has a smaller bore (3.736"), and is useless for performance applications. The bore stroke ratio is so stupidly out of whack, that you can't really do much with it. The 283 has a 3.875" bore, the 262 is 3.670", and the 265 is 3.750" just for reference purposes, and these are pretty much useless for performance as well. The piston pin placement in relationship to the top of the piston is how they compensated for the different crank strokes. All smallblocks except the 400 use a 5.7" long connecting rod. The 400 had to use a shorter rod (5.65" I think), because the piston pin would have been in the oil scraper ring groove to keep it from coming out the top of the block with the standard 5.7" rod. That is why 400's are good for low RPM, but not high RPM. The connecting rod angle at mid-stroke, created by the short rod, puts a lot of strain on the crank.