I have heard of all kinds of ways to raise the compression for the 351m/400 engines and was wondering if it would be possible to shave the top or the crown of stock 400 dished pistons to fit a 351m? basicly machining a flat top piston for the 351m to raise compression. it seems like it would be cheaper and less involved than milling heads,blocks, intakes, and shorter pushrods that are involved with shaving or milling a significant amount from these motors.

 

never measured the thickness of a 400 piston. need atleast .200ths i would guess. 351m can run but never really considered much. just do a 400 and easier to build with parts available. will look into this!

 

Well I was wrong, the 400 piston will not work in the 351m, the 400 piston has a shorter compression height. but the 351m piston with 0.3 shaved from the top will make for 0 deck height in a 400. (not sure about the valve reliefs though)
Still wondering if stock milled 351m pistons would be a cheaper alternative to custom pistons for a 400 build?

the compression height (distance from wrist pin centerline to piston top) of 351C pistons is compatible with 400 pistons. Stock compression heights of the various 351C pistons range from 1.631" to 1.657". The compression height of the stock 400 piston is 1.650". (Remember, the 351M uses the same rod as the 400 with 0.50" less stroke, so its piston compression height is much taller than the 400 piston to make up for the different stroke with the same rod. The 351M piston compression height is 1.947".)

 

400 ford crank/pistons is a simple upgrade but depends on your budget. more pistons available for the 400 setup. i have run the cleveland pistons in my 400 and good to go. simple way to make compression and run a flattop to help on quench in open chambered heads.