I know it is possible to put a 292 crank in a 250, but I have heard that those engines don't hang together very well. I've also heard lots of negative feedback on running a 4 inch bore in a 250. Now here's what I am wondering. Can you offset grind the crank and stroke a 250 1/8"? If so, what rods would you have to use. And what would the crank work cost? If it is feasible this would give you 267 CID if bored .060, and I think the longer stroke would make the motor even stronger at low and mid range revs.
It's pretty easy to get .75 hp per inch out of a 250. On that basis, theoretically, the additional 17 inches would mean an additional 12.75 horses. Ya never now when 12 horses might be enough to shut down some mouthy kid in a rice burner, or some clown from the 350 bolt on billet store!
Boo
