351M Question

[i-w]

i would like to know if the Harmonic Balancers are the same on the 351M as the 400? the reason is i am thinking of converting the 351M to a 400. I believe the only difference i keep hearing about is that the crank and pistons are the only difference. i know the crank is a 3.5 stroke and the 400 is a 4.0 stroke. that is why i was wondering. the 4.0 stroke 400 might need a different balancer to counter the heavier 400 crank. it may be a little heavier but i believe there might be enough difference to require a different balancer. Thanks.

[TMI]

both balancers are a 28 oz imbalance. actual weight of a balancer does not affect engine balance. As long as timing marks are the same, you would be fine. Chances are you would have your machinist balance the rotating assembly anyway. New aftermarket pistons are considerably lighter than the OE, then balancing really is a must anyway.

I have seen a picture of a different timing indicator location, but it has to be extremely rare.

IF a person purchased a new balancer for a 351M or a 400, you would get the same part number anyway.

[mark a.]

You could even use one off a 351 Cleveland but if you building a new motor & getting it balanced I'd just get a new one.

[father/son]

hi iw, for what it is worth, if you decide to buy new, we encourage to check with TMI. no brag, just fact, we bought one. it is sweet. the price was very fair and what we liked the best was the index marks. it was well laid out and during our build we checked the damp marks against no 1 cyl top dead center with a dial indicator. it was dead on. i mean absoulete dead on. we were very happy with it because it did not need modify and top center/ o mark are so dearly important. ps we did have our entire rotating assbly including flywheel and pressure plate. and tmi,s damp.balanced its very important if you stroke . hope this helps. paul md.

[grclark351]

from the factory the mass was different between the 351M and 400, but as Tim states if you buy a new balancer from Ford or anywhere else you'll get the same part for either engine. there's also a 302 balancer that is usable but the timing marks are in the wrong place, a stick-on timing tape can be used to correct it, that's what i have on my 351C right now

here's a pic of the pointers for both sides, if a guy was to need a balancer for the pointer on the right good luck! a timing tape or the 302 balancer might be the only way, then again an aftermarket multi-scaled unit might work?

[i-w]

Thanks for all your help. Great info.