400 (6.6) ?

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Mar 12, 2010 | 08:01 PM

karjunkie

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From: Lexington. Mi.

400 (6.6) ?

hi, i was wondering how to tell if the motor in my 77 short box is a 400 or if it is something else, i can see that the timing cover is not like a 302 or a 351 its part of the block, any help would be nice thanks

Mar 12, 2010 | 08:24 PM

wyckedcombo17

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From: Suburbs of Chicago

if you count the valve cover bolts you should have 8 of them. That'll put you in the right family. To be 100% sure i think you have to drop the oil pan

Mar 12, 2010 | 08:47 PM

karjunkie

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From: Lexington. Mi.

not too shure right now, but i will check that when i get to the truck, how would i tell by dropping the pan?

Mar 12, 2010 | 08:50 PM

Behemoth

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From: Spokane, WA

You don't necessarily have to go so far as to drop the oil pan. Like he said, if you have 8 valve cover bolts, you're in the 335 class of engines (351C, 351M, 400). Remove a spark plug, and rotate the crank so the piston is TDC, then stick a skinny screwdriver, or a straight piece of safety wire into the hole, and have someone rotate the crank. If you get more than 3.5" of travel, you have a 400....if you get 3.5" of travel or less, you have a 351M. That simple.

The 400 has 4 inches of stroke, while the 351M has 3.5. So, if you can measure the stroke, albiet not precise, as long as it is OVER 3.5", you've got a 400. Anything less, it's a 351M.

Mar 12, 2010 | 08:59 PM

karjunkie

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From: Lexington. Mi.

i have A 302 in my ranger, and a 351W in my dads garage and the motor in my 77 looks bigger than the351W, i might be wrong though the 351 is on the roller cart and is throwing my judgment off a lil, i will try your suggestion though, and thanks for the info for the FoMoCo

Mar 12, 2010 | 10:08 PM

Behemoth

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From: Spokane, WA

The engine in your 77 should look bigger than your 351W. The 351M is just a destroked 400. It has exactly the same block, just a shorter stroke. The 400 is basically a tall decked 351C, so it is a bit larger in size, hence the appearance that your engine looks larger than your 351W. The quick answer is all in the stroke...nothing else.