i just got this engine, i was told it was a 400ci, i am not sure if it s, mabe a 351m. with out checking the bore and stroke, how do i find out?

 

What is the engine code letter in the VIN number that might tell you if the engine is original.400 engine code letter is an S and is the second digit in the VIN.

 

Vin #'s mean squat when determining the engine size on certain
engines like the 351M/400 or the 30/390.
You have to physically measure them.

The only way to verify what engine it is.... is to measure the stroke.

You do that by using a piece of dowel or rubber hose or something like that in thru the sparkplug hole.
You get the piston to BDC and make a mark at a point where you can get the second mark to it., Now bring the piston to TDC and make a mark.
If the distance is 4" the engine is a 400
.
If it is less than 4" te engine is a 351M.

 

isn't there a valve cover label under the grime on the driver side.

 

Most of them that I have seen say 351M/400 engine family, but it has been awhile since I have seen a 351M or 400.

 

heres how you tell a 351m does a 1 foot burnout and a 400 does a 2 foot burnout.

 

Oh unlike my 460, it will do a 2 block burn out.

 

that would be nice but the c6 does allow that to happen.

 

Mine just melts the ice down to the pavement, and then I can leave the intersection!

 

Wait'll you see my 351M. 60' and 18MPG.

Your Vin Code will give the best clue,

F150 4x4 starts F14S
F150 4x2 starts F15S
Thats a 400, 351M/W had the same code, H, but its not a Wheezer, because ford didn't put 351W's in trucks.