I just need to know if anyone has done this? I have had the trusty old M to the machine shop and want to start to put it back together. I have purchased a 400 crank, before i put this in i was thinking why not use 351C pistons in it. They have the same bore and compression height as a 400 and have a wide selection a compression ratios. The block was bored .030 so thiswould give me a 406 ci cleveland. Any help would be appreciated.

 

you have to put bushings in the rod ends to get the 351C pistons to work. the 351M/400 have bigger wristpins.

"this would give me a 406 ci cleveland" umm, no... it would give you a 406ci 400 with 351C pistons.

 

Tmeyerinc.com Has everything in stock to do what you want.

 

the 351m has a taller deck height

 

dude, just use the 400 pistons. and the 400 crank. you dont need anything else.

 

If your looking to up the compression a little do as snowfighter says and contact timmeyer inc. He has the stuff.

 

If you want to get really technical, it is really a 402. I don't know why but that is how the numbers come up as. So you would really have a 408.

 

Well if you really really want to get technical you have to figure out which heads you are using and the head gasket and see how far you are in the hole after the pistons are in. Mine, which is .030 over comes out to just a few cc's under a 410.

 

How about a little math help?

Displacement is determined only by bore, stroke, and number of cylinders.

Bore is the diameter of the cylinder. Stroke is distance from TDC to BDC, determined by the length of the crankshaft throw.

Displacement is the volume of the cylinder through which the piston moves, multiplied by the number of cylinders in the engine. It is not affected by any other dimension, including deck clearance, chamber volume, clearance volume, etc.

BTW: All of those other dimensions, along with displacement (i.e., swept volume) are used to calculate the "static" compression ratio.

The formula for volume of a cylinder is: pi x r^2 x H

pi = 3.1416 (constant)

r = diameter/2

H = stroke

So if the bore is 4.030" (4.00" stock overbored by 0.030"), and the stroke is 4.00" (stock), the displacement of each cylinder is:

pi x (4.030/2 x 4.030/2) x 4.00 =

3.1416 x (2.015 x 2.015) x 4.00 =

3.1416 x 4.0602 x 4.00 = 51.022

So the total engine displacement is:

51.022 x 8 = 408.18 cubic inches

The main unique characteristic of a "Cleveland" engine is the block (although the 351C crankshaft and connecting rods are also unique). That differentiates it from all other Ford engines, including its fellow 335-series family members, the 351M and 400, which use nearly identical cylinder heads. Using 351C parts with a 351M/400 cylinder block means you will have a 351M or 400 with "Cleveland" parts in it. You can call it a "400 Cleveland" or whatever you want, though.

Yes, the 351C pistons give you a lot of options for compression height and piston top design, but you have to either bush the pin in the rod, or bore out the pin boss in the 351C piston to make room for the larger M-block pin. Both of those solutions can be serviceable, but neither is ideal for maximum strength. IMO, if you keep the engine speed below 6K rpm, you will not have any trouble with bushed rods. Viability of boring the piston pin boss depends on the design of the piston. With some pistons, it's probably ok, but it might not be ok with others.