383 magnum versus 383 big block
The beauty of the magnum is factory roller lifters and the ability to use a factory O/D transmission
As for the trans you can bolt that onto any SBM
As for roller lifters, that is a benefit.
As for a roller cam, at your stated useage, I doubt the Magnum is much if any advantage. The clearance ramps on hydraulic roller cams are very long and very slow... sometimes nearly three cam sizes greater from advertised to .050,never mind to fully closed.This allows a lot of cylinder pressure at low rpm, to escape back up into the intake. And for a streeter, the vast majority of it's time is spent where? Riiight, at low rpm. And that blows the efficiency angle right outta the water. So, IMO you'd be better off with a fast-rate FTH cam and best would be a solid lifter, narrower than 112 LSA. The point being; In this case I see very little advantage to a Magnum.
Also;it is impossible to build a 318 to 383 with a 4 " stroke;even at 3.91 bore, it comes to 384.25. And can you even find a Magnum with round bores at 3.91 bore? IDK .....
By the time you clean up the cylinders to round and straight, at .020, the cubes have climbed to 388. You'll be in the same pickle as the later 396 Chevelles.... which were actually 402s , as if it made a difference,lol.
