It's my understanding that the smog-era 351M is little other than a 351C with larger combustion chambers for lower compression. Are there other differences of which I should be aware? Do these engines have similar performance potential? Also, can a 351M be swapped in place of a 1980s 5.0 Windsor with any ease? Thanks, Dave
The 351M and 351C engines share some similar features and even a LITTLE BIT of parts interchangeability, but they are different motors! For starters, the 351C uses the small block Ford bellhousing and motor mount bolt patterns, It will physically bolt in where a Windsor based V8 used to sit. The Cleveland also uses a different intake manifold than the 351/400M, but exhaust manifolds, headers, valve covers, distributors and a few other parts will swap out between C and M engines. The 351/400M uses the Lima Series (370,429,460) big block V8 bellhousing and motor mount bolt patterns, so it won't directly bolt in where a Windsor based small block or Cleveland went without switching transmissions (or bellhousings in C4 or manual trans applications) and changing motor mounts. It will bolt in where a 429/460 engine went, however. Cleveland heads come in 2 barrel and 4 barrel designations, and can be identified quickly and easily by the small number cast into the head. It is visible just outside the upper corner of the valve cover, it will either be a "2" or a "4". (351/400M heads have no number cast in this location at all). The 2 barrel heads came from the factory on engines equipped with cast iron 2v intake manifolds, and the 4 barrel heads came on Cobra-Jet and other factory 4v equipped Cleveland engines. The ports in the 4v heads are HUGE, and the 2v heads actually work better in most street/strip applications, so many aftermarket intake manifolds are available to bolt 4v carbs onto 2v heads. The Aussie heads from Australia are the best bet yet...utilizing 4v combustion chambers with 2v ports for the best of both worlds! There are also aftermarket aluminum intakes available for the 351/400M engines. The 351/400M motors can run pretty strong, but they're best used in applications where torque and lower rpm power is the order of the day. Equipped with a mild cam, aftermarket intake, good ignition system, Holley carb, headers and coupled to a decent drivetrain, they will deliver acceptable performance. But of course, they are HEAVY engines...not the flyweights that the Windsor based small blocks are!
Unless your towing, stay away from the 351M/400M engines. If you are lookign for an easy 302/5.0 swap look no farther than the 351W. They're everywhere. They can be stroked to 418 inches easily (427 inches with some considerations). They use the same bellhousing pattern as the 302. They use the same heads, timing cover and water pump.. They're almost all the same (virtually unchaged throughout production - 69, some 70 blocks have shorter deck height, around '93 roller cams became part of some engines). They're tough. If you want more info on them or have any questions, let me know. Now if you absolutly want the do a 351M (or already have it and it was free), you can get them to work quite well but they are one of Ford's red headed stepchild engines. A simple, but powerful 351M would be lightly ported (clened up really) heads, Edelbrock, Weiand or Offy 4 barrel intake, 351C/351M/400M/429/460 distributor, comp cams camshaft (same cam as a Cleveland), and a correctly done bottom end rebuild with KB pistons. For the work involved I'd do a 400M (same block, different crank) if you are dead set on doing a M engine. You would be further ahead to build a 351W for the money, but it can be done.
need to mention that the M series has a taller deck than the standard Cleveland. so intakes don't swap and the engine is wider. they will go in place of the smaller engines, but smaller Fords run out of room pretty quickly - Fox chassis, Mustang 2, falcons, etc.
Ah, so, in essence, a good truck motor, but not really a hot rod engine. I was just wondering, because I have a good runner in an old F250 and was thinking of things to do with it besides plow snow. Thought it might make a nice winter beater if swapped into a '79-'91 Crown Vic with a 4-speed, but that's not really HAMB-appropriate talk so I left that out.
I have 351M in my '57 Ranch Wagon (in place when I bought the car). It's big, ugly, heavy, slow and it runs kind of warm, but at least it gets terrible gas milage . Even with all of these faults, the engine has been very reliable (that's why it's still in the car). I'll probably keep running this one until it dies (which may be never), but I would not choose another 351M to put in any other car.
Sounds like you already have a decent 351 to work with in your F250. IF you reconsider, look into the 351 Windsor. You get all of that low end torque for burnouts at the stoplight, and most of the parts available for the 302s will fit the 351W. (Deck height taller for stroke. 302 head will work as well). I put a '69 351W that I got for $100 in my 49 Ford Coupe. Got it rebuilt as a short block and did the rest myself. Did it all on the cheap. It screams! Plenty of horses left even when I put my foot into it. Your call. DF
I had a Cleveland in my 49 Lincoln-- It has tons of power. Came on kinda slow and then would scare you-- Driving a 5,000 pound car with 50 year old drum brakes!
Knowing your affection for T's Bigcheese327, the Cleveland - or 351M for that matter - would be a good T engine. Just to plant a seed for an idea.....
hahaha, not this T. This is definitely going to be 'banger powered. I'm just exploring daily-driver ideas with this. Since you're from Rochester, I'm sure you've got a good idea how poor a T touring would be in a Michigan winter. By the way, did my pics ever come back? They were still showing up fine for me.
LOL!! Yeah you get winter as bad as, or worse, than we do! I forgot all about the pics, I'll have to check. EDIT: Still red X's, but I just realized it could be our work IT filter thing. It can be sensitive sometimes.
If you think a 400M won`t run go over to the 351C website 351CLEVELAND.NET. They run a lot of big inch Clevelands. Also they did make a 400M with a small block bellhousing a 400FMX block. Just a little more info on Cleveland .Gasserman
Similar in design but '69 BOSS 302's have their own specific castings as do the '70 heads. both of them are different than any Cleveland head.
351 C are really popular here in Australia, lots of people running them as they were in production till 82/3 from memory. lots of local go fast goodie, probably the most popular SBF drag motor. I prefer the windsors myself, but the clevo's have a huge following. Some are making huge outputs too. checkout www.airflowdynamics.com.au for heads and google the 'funneweb' intake.
The problem with the 351M is the large deck clearance; the piston is way down in the hole and they're dished. You can build a 9:1 400 by using 351C flat-tops and bushing the rods down to receive a 351C wrist pin (the 400 uses a larger pin). Details on 351Cleveland.net. Just put in a 400 crank, and it's no longer a 351M. From time to time, you'll find 400 flat-top pistons on ebay or elsewhere. They're direct replacement, and they're under the name of Badger (P/N 40010F) or Ohio Piston/Ertel/Nylen (P/N 1282).
What are the tranny options (Manual and auto) for the 351M and 400M? I want to replace the FMX behind my Midland because it's slipping pretty bad. What's the best way to go tranny-wize?
Any transmission or bellhousing that bolts to a 429/460 engine will work behind a 351/400M. You can run a C6, or even a C4 with the one-year bellhousing that fits the M engine to the smaller automatic tranny. Manual choices include the old Toploader four speeds of the late 60s to late 70s, and even five speed truck trannys found in early 90s F250s, although those are pretty big and not ideal for use in cars!
The 351M/400 has long been ignored by the performance market, but their potential is starting to be developed. A guy amed Tim Myers has developed a 434 stroker kit with these results; http://www.tmeyerinc.com/434dyno.MOV
Clevelands are externally balanced at 28oz, just like the early Windsor blocks. Flywheel/flexplates are interchangeable.
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