400 or 351m

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Dec 12, 2002 | 08:22 PM

dustinleavitt2000

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From: ca

400 or 351m

now I know this question has been asked before but how do i tell if I have a 351m or a 400? Heres my problem i know this engine is not the original and I know that the valve covers and intake and stuff arent from this engine. it started with a 400 and i blew up or something then someone put another motor in and used the heads valve covers and stuff on it. so how do I tell? i have the crank and pistons out. the pistons say 400 on them so I assume that stands for cubic inch but im not sure and im not sure if the 400 and 351 pistons are the same please help?

Dec 12, 2002 | 09:20 PM

grclark351

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From: chicago burbs

400 or 351m

Dec 12, 2002 | 10:56 PM

grclark351

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From: chicago burbs

400 or 351m

easiest way is to look at the crank.casting # of a 400" is 5m,5ma or 5mab.a 351m crank cast # is 1k-found on the front counterwight.piston comp. hight(top of piston to center of pin)is 1.947(about 2")for the 351m,and1.65(about1 5/8")for the 400

Dec 13, 2002 | 11:12 AM

Bill_Beyer

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From: PacNW

400 or 351m

400 and 351M pistons are 2 different animals and will not interchange. Most OEM Ford pistons have the engine CID marked on them. If yours say 400 then it's a 400.