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Discussion Starter #1
This is a question for those who really know thier 335 series. I'm going to be rebuilding the engine that was in my '79 when I bought it. My question is when I pulled this engine I think the valve cover sticker (sticker now gone)said it was a 400. i've ran the vin on the truck it says it came originally with the 351. My hi-per ford book says the only way to tell the difference between the two is to measure the stroke. My question is when I pulled the pistons they are stamped with a 400. Does that stand for 4.00" bore(both have same bore), or stand for 400 cu. I'm thinking I want to build a 400 but, mainly want to know of some way of knowing for sure what I'm starting with. By the way when I pulled this motor it had the 11" clutch(351M) but, I know they are interchangable with the 12". (As far as crank patterns) Any help would be great.
 

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sounds like a 400 to me.......if the pistons were oversized it should only be stamped with the amount over stock
 

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If your rebuilding it,it shouldn't really matter what you had.Just be sure to order 400 pistons,and get a 400 crank.That is the only difference between the 2.There is also a forging number you can go buy on the crank,I think someone here has the the number for the 351 and 400.
 

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The pistons are indeed marked with '400' if it is a 400, right next to the wrist pin hole. If the bore is stock, there will be no marks on the head of the piston. If the engine has been bored, the overbore dimension will be stamped in the top of the pistons.

Few of the factory flywheels cam drilled for the 12" clutch..onlyu F-350s and larger used the big clutch in 'most' cases. The 11" is fine for even built engines. Or you can buy a new aftermarket flywheel and they are usually drilled for both clutches.
 

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Discussion Starter #6
Thanks for the input. These are definatly stock bore pistons, no oversizes on face of the piston. Next time I'm out in the shop I'll have to check the crank for those #'s. Do you know where they put those #'s on the crank?
 

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I should post a picture..but here goes. On the first counterweight back from the nose, but on the 'side' of the weight next to the smaller diameter part of that section of crank. er?, you say...the numbers/letters are actually pretty large since they were cast in.
 

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Discussion Starter #8
Well, that smaller part of that crank that your referring to is the "throw" and your right it's right on the side of the counter-weight. Mine stamped 5MAB I also measured the side of the cylinder to double check and it's 4.00" which is the 400's stroke, (351m is 3.50"). Thanks for the help and Happy Holidays to all the members on this forum.
 

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I always referred to the rod journal offset part as the 'throw'. And the weights you hang on the rod journal when balancing the crank as 'throw weights'.:thumbup

Good luck with the buildup..the 400 is a sweet engine if woken up properly. We build quite a few.
 

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bmc69 said:
Few of the factory flywheels cam drilled for the 12" clutch..onlyu F-350s and larger used the big clutch in 'most' cases. The 11" is fine for even built engines. Or you can buy a new aftermarket flywheel and they are usually drilled for both clutches.
My 78 had one and it sure looked bone stock when I got it over 10 years ago. And since it is out and in the attic, I might evn get the PN for ya (if it is original). :thumbup
 

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OX1 said:
My 78 had one and it sure looked bone stock when I got it over 10 years ago. And since it is out and in the attic, I might evn get the PN for ya (if it is original). :thumbup
Get the Ford number off it if ya can, OX. Thanks...I might just be plain unlucky but even the 400 out of my F-250 was only drilled for the 11"...

I'll trade ya a drivers side exhaust manifold for a 302 EB for the numbers.:rofl:

speaking of which..did you ever send me your shipping addy..or was I just slow and missed it?
 

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bmc69 said:
Get the Ford number off it if ya can, OX. Thanks...I might just be plain unlucky but even the 400 out of my F-250 was only drilled for the 11"...

I'll trade ya a drivers side exhaust manifold for a 302 EB for the numbers.:rofl:

speaking of which..did you ever send me your shipping addy..or was I just slow and missed it?
Sent you a PM.
 
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