i have a 400 4 speed im taking out to rebuild, meanwhile i have 351m putting in truck while rebuilding the other, question is will the 400 flywheel fit the 351? i know the 400 has 12in clutch and 351 has 11, thats y asking?

 

Yeah, it'll fit and work fine.

 

thanks, for the info, but y is the 351m call for 11 in clutch where as the 400 calls for 12? but yet the flywheels will interchange>?

 

If I am understanding that there is a question there .... yes, you just use the matching cflutch for the flywheel being used. You can use a 400 flywheel on a 351m but you have to use the 12" clutch to match it (and you can use a 351m's flywheel on a 400, but you have to use a 11" clutch with it).

351M and 400 is same except for the stroke of the crankshaft and the pistons .... but back there at the back of the motor there is no difference. They even use the same block. In fact, if an automatic they use same flexplate. Ford just supplied a larger clutch for the 400 to handle more torque longer and so the flywheel is drilled for the larger clutch pressure plate.

 

thanks very much

 

i am glad i found this post. i actually got on here to ask the same question. i have a blown up 351M with a brand new clutch and a spare 400 from an automatic so i was wondering if the 351m flywheel would work on the 400. i knew they were different strokes so i wasnt sure if they had a different crankshaft balance or not. I also knew they used a different clutch. If they use the same flywheel, is there any chance that the flywheel would happen to be drilled for both sizes of clutches?

 

Well heres ya some advice, 351m uses 11 inch, 400 uses 12 inch, buttt,,,,,,,,, there r 2 of both theres a 12 and 3/8,,,, and 12 and 5/8 for ur pp bolt pattern, i just got set back few days over this, now waiting on right clutch

 

good to know. thanks