Originally Posted by JBronco

The quickest way of differentiating between the different familys of Ford engines is to simply count the valve cover bolts.
2 bolts: 239/256/272/292/312 (produced from 1954 to 1964)
5 bolts: 332/352/360/361/390/391/406/410/427/428 (FE engine)
6 bolts: 221/260/289/302/351W
7 bolts: 429/460
8 bolts: 351C/351M/400
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The early 351W has four extra intake manifold bolts (13, 14, 15 and 16). If you see them, it's definitely a 351W.

Windsor engine characteristics

Thermostat housing bolted to the front of the intake manifold

All 289/302/351's have intake bolts 90 degrees to the ground

289/302/351's have evenly spaced exhausts aimed 90 degrees from length of head

5/8" (18mm) spark plugs

The 351W and 302 are very different:

The 351W has a taller deck height than the 302. (a 302 will have the intake almost flush with the base of the distributor... where it goes into the block..... a 351w will have about 1/2 inch lip there where the intake meets the block.)

Since the deck height is taller the intake manifold is wider on the 351w than on the 302.

The 351W uses a larger main journal than the 302. there are 2 physical ways of telling a 302 vs. a 351w. Also, in between the frost plugs on a 351W there will be what appears to be a triangle or diamond (the way I was told) indented cast into the block...a 302 doesn't have those.

a 351W is wider between the heads compared to a 302 (the intake manifold is wider by about 1-1/2") and 351 pistons have a different pin height. You can use 302 pistons in a 351 if you stroke it to a 393

quick ID tip: The lower thermostat housing bolt on the 302 will be below the top of the water pump and you won't be able to put a socket on it. On the 351W you can remove the bolt with a socket.

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.

The 302C is a de-stroked Cleveland, the block is identical to a 351C, but the crank rods and pistons are all engine specific. The 302C heads are the small combustion chamber, small runner heads.

M-series engine characteristics

The 351M/400 was only available with small ports, same as 351C 2V. An Edelbrock Performer for these are wider and should say Performer 400 on the top.

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.


This is a very rare Ford 400 block, one of a very few cast to fit the standard Cleveland bellhousing. These blocks have blank engine mount bosses which can be drilled to suit standard Cleveland engine mounts making them a direct replacement for a 351C (assuming no height/width problems).

All engines in the M 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.

Originally Posted by rla2005

Great info from Fordman96 but the short version is you have a 351W. It does not share the same transmission bellhousing pattern as the 460.

Originally Posted by Fordman96

This is from a thread in the bronco forum I found because I know the question had been asked there a few times.

Originally Posted by Conaski

The 351C never made it out of the '60's. The M didn't get past 1980.

Originally Posted by Tinterat

I think i read once that they stopped making the 351M and C in the early 80s.

Originally Posted by Conanski

The 351c never made it out of the '60's and was never factory installed in a truck. The M didn't get past 1980 and therefore was never produced with any type of fuel injection, so by a process of elimination if the truck in question has a fuel injected motor it can only be a 5.8/351w.