Basic block question
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Mountain Pass
Joined: Feb 2015
Posts: 167
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From: Virginia
Basic block question
and no need to mention the Windsor. It is known to be completely different. Strictly 351C vs 351M
So up until the other day I believed the 351cleaveland while similar where for the most part entirely different from the 351M/400.
Simply, are they basically the same (except for minor differences)? Same heads? Etc?
or are they legitimately different? Not really interchangeable?
i always believed Cleveland’s to be fairly uncommon. But it seems like the 351M are all in my favorite 73-79 Ford trucks. And dare I say plentiful
educate me. not really a fan of the 351M because of the limited production (limits aftermarket). And prefer SBF for that same aftermarket reason.
V/R
Hawkins
VA
So up until the other day I believed the 351cleaveland while similar where for the most part entirely different from the 351M/400.
Simply, are they basically the same (except for minor differences)? Same heads? Etc?
or are they legitimately different? Not really interchangeable?
i always believed Cleveland’s to be fairly uncommon. But it seems like the 351M are all in my favorite 73-79 Ford trucks. And dare I say plentiful
educate me. not really a fan of the 351M because of the limited production (limits aftermarket). And prefer SBF for that same aftermarket reason.
V/R
Hawkins
VA
Super Moderator
Joined: Apr 2004
Posts: 34,470
Likes: 2,799
The biggest difference is deck height.
The 351C was 9.206
Some had 4 bolt mains
They use the same block to bell pattern as the 289-302-351W.
Heads were open chamber or closed, with valves either 2.04/1.66 or 2.19/1.71
The 400/351M are identical other than stroke via crank and pistons. 400 first in '71, 351M added in '75.
The deck height is 10.297
All 2 bolt mains
Block to bell is same as 429/460 except for one with the SBF pattern in '71. (The "FMX block")
Heads all open chamber with 2.04/1.66 valves.
You can spend a lot of money trying to make a peformance engine out of a 351M as you are looking at custom or reworked pistons.
The 400 has aftermarket pistons.
A cam change and a 4bbl will bring the 351M out of the 130 HP coma to a higher but still sleepy level.
The 351C was 9.206
Some had 4 bolt mains
They use the same block to bell pattern as the 289-302-351W.
Heads were open chamber or closed, with valves either 2.04/1.66 or 2.19/1.71
The 400/351M are identical other than stroke via crank and pistons. 400 first in '71, 351M added in '75.
The deck height is 10.297
All 2 bolt mains
Block to bell is same as 429/460 except for one with the SBF pattern in '71. (The "FMX block")
Heads all open chamber with 2.04/1.66 valves.
You can spend a lot of money trying to make a peformance engine out of a 351M as you are looking at custom or reworked pistons.
The 400 has aftermarket pistons.
A cam change and a 4bbl will bring the 351M out of the 130 HP coma to a higher but still sleepy level.
Laughing Gas
Joined: Sep 2013
Posts: 1,112
Likes: 101
From: North Idaho
The 400 and 351M are tall deck Clevelands with 351W size main bearings. That's about as simple a way as there is to think about it I think. And as stated they almost all use the big block bellhousing pattern.
You could use a 351C crankshaft in one, but would need to run main bearing spacers. I think a 351W crankshaft can also be used, but with a spacer on the crank snout.
351C intake manifolds can be used, but again... you must use spacers.
You could use a 351C crankshaft in one, but would need to run main bearing spacers. I think a 351W crankshaft can also be used, but with a spacer on the crank snout.
351C intake manifolds can be used, but again... you must use spacers.
More Turbo
Joined: Sep 2003
Posts: 512
Likes: 26
Sorry to burst the bubble.
There's nothing a 351M can do that a 400 won't do better. The 400 was designed to replace the 390 and the 6.580"rods give a great rod/stroke ratio with a 4" stroke. When the 351C was discontinued, Ford couldn't make enough 351Ws so they destroked the 400. Usually an engine family gets bigger but here the big engine came first. The 351M kept the long rod but with a shorter stroke the R/S ratio isn't good for the street. So the 351M is an oddball beancounter compromise. The 400s longer stroke, smaller R/S ratio and more cubes make it much much better for pulling loads and lower end grunt. Or moving around 2 1/2 ton "Thunderbirds"!
R.
There's nothing a 351M can do that a 400 won't do better. The 400 was designed to replace the 390 and the 6.580"rods give a great rod/stroke ratio with a 4" stroke. When the 351C was discontinued, Ford couldn't make enough 351Ws so they destroked the 400. Usually an engine family gets bigger but here the big engine came first. The 351M kept the long rod but with a shorter stroke the R/S ratio isn't good for the street. So the 351M is an oddball beancounter compromise. The 400s longer stroke, smaller R/S ratio and more cubes make it much much better for pulling loads and lower end grunt. Or moving around 2 1/2 ton "Thunderbirds"!
R.
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