My 79 ford f250 has a 400 in it. NOT a 400m. The 400 would be bigger than the 400m right? Don't the 400m have 351 rods and crank in it to D stroke it? Would that make it smaller?

 

There was never a 400M motor only a 351M. The 400 is just what it says, 400. I believe the crank and rods are different in the 351M from the 400. the pistons I think are the same as is the bore size.

 

People get this confused all the time... the 351m and the 400 are in the same engine family... a 400 is a 400, and it's the only one Ford ever made.

 

3.5" stroke on the 351
4" stroke on the 400
4" bore on both

 

oh, were it so simple! there are two different 400's. they are both based on the same engine but one has a bellhousing bolt pattern like the 429/460 and the other rarer and more desireable engine has the bellhousing pattern for a small block. the second style was only made one year and are very high in demand. hawkrod

 

My point is though, they are both still basically the same engine.

Some say that Ford made a 400 small- and a 400 big-block, two completely different engines. Bolt patterns aside, this is simply not true!

 

I don't have any literature on there being a second 400.

The 400 is a 335 engine series and considered a small block with a big block (385 series) bolt pattern.

One of the biggest mistakes is when people put an M after the 400.

The correct engine ID is 351M/400