How to tell a 351m from a 400? The engine is out of the truck and is complete, what is the best method of finding this out without taking it apart? Thanks, Tim
The two are visually identical externally. The only way to tell is to measure the stroke, 351M = 3-1/2", 400 = 4". Stick a length of wire through the spark plug hole and rotate the engine to determine stroke. Could be a little difficult due to the design of the heads.
remove the oil pan and check for a raw casting on the crankshaft almost always located in the counterweight of the first throw, if its a 5m-5ma its a 400 and if its a ik itsa 351m.
the only way of messuring acuratly the stroke is by removing one head, its impossible to do it by the sprak pplug method, check this out: M-Block 351M/400 Parts Reference
check the crankshaft part....goodluck!
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"All right baby, see what I´ve got right here in my hands, I´ve got it right in my hands to score you baby, I think im gonna yank on a one town! Look Out!" Uncle Ted
You can also move piston to bdc, fill the cylinder with oil after you thread in a fitting and piece of clear tubing, then crank engine by hand until no more oil comes out. Carefully measure the displaced oil, convert to cubic inches, and multiply by 8 cylinders.
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Mark in FL
restoretherepublic.com
hmm you can also check the stroke of the piston by measuring the distance the piston travels in the cyllinder by removing the oil pan and turning the engine bu hand, should be the easiest way....
__________________
"All right baby, see what I´ve got right here in my hands, I´ve got it right in my hands to score you baby, I think im gonna yank on a one town! Look Out!" Uncle Ted
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