Originally Posted by Maalyg
Thanks for the information. I'm trying to figure out if this motor is a w30 or w40... Is it another section on the block that might provide me with that information? I'm getting ready to rebuild it and I wanted to know more about the motor before I got started.
If you have to ask if it's a W-30 motor, then it almost certainly is not. There is no such thing as a 455 W-40.
Depending on the year, the W-30 motors had unique heads, valves, cams, and intake manifolds. All of those parts can be bolted onto any 455 block. There are no numbers anywhere on the motor that will "prove" is it a W-30. Heck, prior to the 1972 model year, there was nothing anywhere on the car that would prove it. The only proof is if you have a factory build sheet that shows the W-30 option and that matches the VIN derivative on the block. And before you ask, no, these build sheets are not available from any source, so unless the build sheet can be found inside the car (and there's no guarantee of that) then there is no way to prove it.