I am still on the fence about what motor I actually have, everytime I convince myself it's a Cleveland, I see something contrary. The heads are "M" heads, but since the 2 are interchangable who knows and there are other block characteristics that still make me think Cleveland. I know some guys on here are well versed in this area so looking to verify one way or the other without pulling the starter as the top bolt is nealy impossible to get to the way everything is crammed in there. Looking to start pricing and doing some work but need to settle this aggravation once and for all. Thanks as always. I can post up pics if that will help???

I won't be much help on the Cleveland however I do have a 400 m block in my bronco. There is a recessed area to the right of the distributor that is a good in dictator for an m block. I know the c and m blocks both have 6 bolt valve covers so not much help there. I will look up the other notes I have and get back to you.

EDIT: the valve cover has 8 bolts for both the C and M blocks...

I have a 1971 Pantera with a Cleveland. I read that the top of the block by the distributor mount is almost flush on it and on the m the distributor mount is raised by an inch or so. Want a picture so we can compare? Peter

found this as well, might be helpful.

Cleveland engine characteristics

The thermostat housing is on the block extension which contains the timing chain

deck height makes a 351c intake not fit on a 400, Spacer plates are available to use a 351C intake on a 351M/400, but it's more practical to use these mainly for large port intakes on 400s using 351C 4V heads.

351C manifolds are dry, no water passages or thermostat housing....thermostat housing goes into the front of the block.

spark plugs will be the smaller 14mm type

The Cleveland (351C) has the small 300/302/351W bell housing pattern.

M-series (335) engine characteristics

351M/400 manifolds are dry, no water passages or thermostat housing.

There is about a 1" rib cast onto the block on the taller 351M/400 which runs along side the distributor going from the front of the block extension back to the intake manifold.

All engines in the 335 series (family) have the vertical bolt pattern on the fuel pump. That includes 351C, 351M, and 400.

M-block engines have the taller intake manifold front mating surface (almost an inch above the distributor mounting hole and front cover housing) and is quite apparent

The only real differences between a 351M and a 400 are the crank and the pistons.

351M and 400 heads are identical, are also nearly identical to 2V Cleveland heads

The 351M and almost all 400's have the large bell housing pattern like the 429/460.

The only 100% positive way to tell if you have a 351M or 400 is to drop the oil pan and check the casting numbers on the crank. They should be on the side of the first counterweight. A 400 crank will have 5M, 5MA or 5MAB casting code. A 351M crank will have a 1K casting code.

400 with 302 bellhousing was made in '73, and will also have the regular 400 bellhousing mount casting. Top 2 bellhousing bolt holes are 5 inches apart on a 302, 7 3/4 inches on 400. (see image at right)



basically if the distributor is in a sunken area to the right of the thermostat area.. then its a M block...

351C - water hose outlet out of top front of engine faces straight up.
351W - water hose outlet out of top front of manifold faces forward.
Easy peasy!

351 Windsor 351 Cleveland
5-bolt straight valve covers 8 bolt 2-plane valve covers
radiator hose to the intake manifold radiator hose does not connect to intake
regular 5/8" spark plugs small 14mm spark plugs

When you guys visit the garage in Georgetown this summer you will learn what goes on in the little man cave! This Pantera is one of my Dad's cars (he passed away in 2008) that I take care of for the family. It currently has some fried wires that need replacing (anyone in the club good at replacing individual wires?). It runs fantastic however. The 351 c would be a great Bronco motor! I'm also trying to get my 1949 model B john Deere running by the 4th of July if anyone is good with those! Here is a Pantera pic:

Here's a better picture, doesn't help answer point of this thread and the engine question however! P

Very nice!

So cool!

Yah! I love Pantera's very sweet....

So it looks to be a Cleveland with "M" heads??? why would someone do that?