I thought that myself. Until you see them side by side - it isn't real obvious .

I wish the heads had been off the "M" in the pic - it would lay it out better.

There really IS a lot of iron in those blocks - but that is what make both the 400 and 351M noteworthy for strength and reliability.

The Cleveland series had much thinner castings but the same general layout overall.
(You have to magnaflux the crap out of every part of an old Cleve to make sure of it)

They LOOK the same until you look closer.

BIGGEST tell in the Cleve family is the diameter of the crankshaft journals.

The better engines have a smaller (and therefore lighter and easier to spin) crank - which can in turn be made of materials with higher tensile strength throughout.
The "THROW" of that crank is still the same

The tell is in the crank journal diameter. The smaller it is the better...
(You can't stick a light crank into an engine hogged out beyond it in the saddles)

But the M will not be incorporated into anything soon.


NO! IT AIN'T FOR SALE!!!

Even though it has a massive crank - what the heck...

I think when the 4X4 version comes up I will want that.



* AS a matter of fact I will remember these if I ever build a BLOWER motor...