351C or 351M

[Zorm]

Found, what is advertised as a 351C but its in a 80's F250. So since its in the 250, could it be a 351M which I don't want. Is there some way externally I can tell the difference between the two? Can you put 351C valve covers on a 351M? These are aluminium valve covers with the 351 Cleveland cast into the top and that is what the seller is going by.

thanks for thoughts

[fuzzier1]

First off, I am not an expert on 351Cs,Ms or 400s but I have always heard that the 351M was junk. But read this before dismissing them. http://www.fordmuscle.com/archives/2001/11/351M/ I think they can be made to run pretty easily. To be able to tell what you have is measure the top two transmission bolt spacing as the M should have the Big Block bolt pattern and the Cleveland will be less. From what I understand 8" between the bolts on the BB and 6" for the Cleveland. Also the Cleveland heads will fit the M motors. Hope this helps.

Fuzz

[Nitekruizer]

A couple more ways to tell by looking, the fuel pump bolts on the 351M/400 are over and under pattern where the pump bolts to the engine, where the Cleveland V8s had the mounting bolts on each side of the fuel pump. There's also a 1" high barrier cast into the upper left front of the 351M/400 block, just left of the distributor (from the driver's point of view).

[Zorm]

Well went and looked at it and it is either a 351m or a 400 with either Cleveland heads and valve covers or just Cleveland valve covers on it I'm not looking for a big block. But I did find a fuel injected 351 Windsor so now I just need to figure out can I use the Ford fuel injection as standalone and what flywheel do I need to go from an automatic to a manual transmission

[dbrandx]

All 351W use a 28 oz balance flywheel. Early model 289/302 also use the same as 351W. Late (`81 and newer) 302/5.0 use a 50 oz balance flywheel. Yes, you can use factory efi on a 351W/5.8. I don't know of an aftermarket wireing harness specifically for the 5.8 but you can do your own from a donor truck if you`re good at wireing. You can also use a car type upper manifold from a passenger car 5.0 HO with an adapter to fit the 5.8 lower manifold. then an aftermarket wireing harness for thu 5.0 would work. I have done that conversion on the 351 in my 74 Bronco. Its probably the single coolest thing I`ve done to any engine over the years. I highly recommend it.

[Zorm]

dbrandx, need to get with you about that FI project. I have been looking at the after market world but if I can do what you did, that would work just as well.

[RottenAppleRed]

A couple more ways to tell by looking, the fuel pump bolts on the 351M/400 are over and under pattern where the pump bolts to the engine, where the Cleveland V8s had the mounting bolts on each side of the fuel pump. There's also a 1" high barrier cast into the upper left front of the 351M/400 block, just left of the distributor (from the driver's point of view).

This is NOT correct. The 351C, 351M and 400 all have the same fuel pump and fuel pump mounting bolt pattern. Others may have already stated this but, the 351C shares several things with the 351M/400, including, but not limited to...cylinder heads (with some differences), valve covers, camshaft, timing components, distributor, water pump and pulleys. Where they differ...block (though the same bore and head bolt pattern, several differences), crank, motor mounts, bell housing pattern, intake, rods, pistons, pushrods and exhaust manifold/headers (they bolt up, but are routed different). The 351M is the product of the 400 cid Ford passenger car engine. This engine was designed to accept the cylinder heads of a Cleveland (same pattern as the small block and 351 Windsor) and mount in the same location as the 429/460 big block Ford...of which they share the motor mounts and bell housing. The 400 has a 4 inch bore (same as the Cleveland, Windsor and 289/302 small block) and a 4 inch stroke. Ford cast this block with a taller deck height to accommodate the increased stroke and rod length. The 400 shares the same crankshaft main bearing journal as the 351 Windsor and that is where the 351M comes from...it is a destroked version of the 400 (400 block, 351W inspired crank...3.50" stroke and a 1/4" taller piston with the same rods). That's where the term "modified" comes from...though Ford didn't note it as such. The M is just a differential from the W of the Windsor.

You cannot tell a Cleveland from a 351M/400 by counting 8 valve cover bolts (same) or the vertical fuel pump pattern (same). You can, however tell those engines from a Windsor with 6 valve cover bolts and a horizontal fuel pump pattern. The way to tell a Cleveland from a 351M/400 is from the shear mass of the 351M/400. They are much wider at the intake and the wingspan of the valve covers than the Cleveland. If you can see the motor mounts, the Cleveland uses the same 2 bolt design as the small blocks and Windsor, that have the holes vertical into the block. The 351M/400 uses the same as the 429/460 that is, I believe a 3 bolt, that bolts straight into the side of the block. The bell housing on the Cleveland is short at the top like the small blocks and Windsors. The 351M/400 top 2 bolts sit much higher than the Cleveland, and its obvious. They are the same as the 429/460.

I hope this helps,
Nate

[Ozblitz]

I believe the 351C. Has a very unique water inlet for the upper radiator hose. It goes straight into the center of the block. It doesn't have the typical 90dg. housing. This is what was told to me, when I thought I had a 352. Guy told me it was a 351c and pointed out the upper inlet.
I can't figure out how to post a picture from my I-pad, so I apologize

[RottenAppleRed]

I believe the 351C. Has a very unique water inlet for the upper radiator hose. It goes straight into the center of the block. It doesn't have the typical 90dg. housing. This is what was told to me, when I thought I had a 352. Guy told me it was a 351c and pointed out the upper inlet.
I can't figure out how to post a picture from my I-pad, so I apologize

It is correct that a Cleveland has a unique water outlet, though it is the same on used on the 351M/400. It is even more unique in the fact that the water exits the block instead of the intake. The Cleveland engine family (335 series) 351C 351M and 400 do not have a water passage that runs to through the intake. This is part of their cooling problem...the heads sit higher than the water outlet in the block, so air gets trapped until the system finally burps it out. This is also the fastest way to tell between 351W and the 335 series engines...the Windsor has the T-stat housing in the intake, like the small blocks, big blocks and FE engines.