[Jay S]

It isn’t that the 4.5” crank doesn’t work, there are even a few Pontiac’s with 4.75” cranks running around on the street. Overall the 4.5” and larger cranks work a lot better in aftermarket blocks with big 4.31” plus bores. More than 4.25” or 4.375” stroke the stock bore is getting out of square enough power gains are harder to find.

I have both 455s and 400 based strokers. We use to rev a 4.25” stroker in a 3.25” main combo (455 block) to 6700 at the end of the straight in a circle track race car. Tracks start out slick, the engine would start out around 6000 RPM then get higher as the night went on. The A feature was 25 laps on a 1/3 mile track, if the car had to go thru the B feature and the heats it was about 40 laps. Pretty much the same as what B-man said…As long as the engine was set up with proper oil clearances, we could never tell any difference between the 3” and 3.25” mains. A stock rod 455 is a pretty long rod compared to a 454.