351M, 351W, 351C, what's the difference?

Discussion in 'Fox 5.0 Mustang Tech' started by Killer50stang, Sep 6, 2006.


  1. Killer50stang

    Killer50stang New Member

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    I know the C=Cleveland and the W=Windsor and the M=Modified, but where is the difference between them all. I have a 351M motor I plan on rebuilding and am curious on the differences.

    Here's what I came up with:

    Now a 351 Windsor is really a slightly enlarged 289/302, as it's name implies it comes from Fords "Windsor" engine family (a.k.a. the 90-degree V engine family). The thin-wall cast SMALL BLOCK accepts regular sized spark plugs, uses a timing chain in the block, routes water through the intake manifold, features thin main-bearing caps, a very good oiling system, and uses the same heads for 2V & 4V versions. The heads are are small, utilizing in-line valves with relatively small ports. The valves are 1.78" intake and 1.54" exhaust, i.e. the same size as a 289/302. The valve covers are straight (front to rear), attached by 5 bolts, and when removed you can see 351 cast in the lifter valley. The small side-by side (in-line) valves are the dead give-away.
    The 351 Cleveland, on the other hand, belongs to Ford's 335 engine family. This thin-wall cast BIG SMALL BLOCK uses the smaller 14mm spark plugs, has a separate front cover (bolted to the block) housing the timing chain and routing water - so that water does not go through the intake manifold, features beefy main caps (wide enough to drill for 4-bolt mains), a poor oiling system, and uses different heads for 2V & 4V versions. The heads make all the difference and these fire breathing babies make this motor the legend it is. On the 4V, the valves are HUGE, measuring 2.19" intake and 1.7n" exhaust (don't remember exactly). Valves this large are only possible via a canted valve arrangement, forming what Ford refers to as a "poly-angle" combustion chamber. The valve covers are not straight - the front is flat and parallel to the ground, but a curve twists the rear parallel to the head. They are attached by 8-bolts and when removed, there is a 4 cast into the corner of the 4V and a 2 cast into the corner of the 2V (at least in 1970). The canted valves are the dead giveaway.

    But what about the modified?



    Jason
     
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  2. 85ragtop

    85ragtop Deputy Dawg Man woods surround my offic

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    The modified was a truck engine, I think. I have one (400m) my self in an F-100. I don’t know a lot about them. The truck is slow as dirt, but it can really tow. It was in the truck when I bought it, so I have never really messed with it.
     
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  3. sbftech

    sbftech Banned

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    if you plan on building an M for performance you should stop now.
     
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  4. 85ragtop

    85ragtop Deputy Dawg Man woods surround my offic

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    I agree, I don’t think there is a lot you do with it. I cant hardly find parts for my truck.
     
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  5. feifong

    feifong New Member

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    wich should u build for perfomance 351w or 351c? do they still make 351c?
     
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  6. 85ragtop

    85ragtop Deputy Dawg Man woods surround my offic

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    My 351w is working nice. I dont think they make a 351c any more, but I could be wrong.
     
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  7. sbftech

    sbftech Banned

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    the cleveland was built from 1970-1974 and when done right will walk away from a windsor. If you have never built a cleveland, I wouldnt tackle it for your first build. The windsor is much easier to build.
     
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  8. dastang2

    dastang2 Active Member

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    the M is a boat anchor.
     
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  9. muh'stang

    muh'stang If I were rich, I'd make sure all the scoops on my

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    the M is a C with better geometry. The C had 5.778" rods, the M had 6.581" rods...the 351m even had 1.98" compression height on the pistons, you could get some 7" rods in one and still have about a 1.48" piston pin height. People rant about how stout a stock 351c can be, and then turn around and call the M a boat anchor.
    The M was a truck motor like stated, and grossly detuned at that. The pistons were way down in the hole, the compression was low, the cam was retarded 4 degrees and both the 351m/400 were majorly starved of a/f. Also, as a truck engine parts were built beefy to ensure a long service life.
    Not to burst your bubble since you seem to be the know all of the M series Ford engines, I wonder if you think a cleveland is a boat anchor:nono:
    anything you can do to a 335 cleveland series engine you can do to the M block 335 series engine, except have more room to expand. That said, I'll say it agian, truck engine.
     
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  10. Foxfan88

    Foxfan88 My Grandpa has great wood.

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    351M is a destroked 400
     
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  11. dastang2

    dastang2 Active Member

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    you said it was built stock like that with all those bad qualities which makes it a boat anchor. nobody is talking about nothing other than stock. also i didn't say anything else other than what i typed, who are you refering to when you say i boasted about a C or calling a C an anchor. my opinion still stand as BOAT ANCHOR
     
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  12. QUIKSVT

    QUIKSVT New Member

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    wow. I never knew how amazing M motors were. I wonder why I never see race cars or fast street cars with an M motor?

    BOAT ANCHOR <--- the troof
     
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  13. sbftech

    sbftech Banned

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    Just as long as noone insults the mighty cleveland, cause then its gloves off. :D
     
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  14. 795.0pacecar

    795.0pacecar lover of pudgy polygamists

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    I hear that lol.
     
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  15. red95gtconvert

    red95gtconvert New Member

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    We used to have an 82 F250 with a 351M in it, that engine was junk and the truck couldn't get out of its own way. My parents were always saying " I wish we would have got the 460 ".
     
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  16. muh'stang

    muh'stang If I were rich, I'd make sure all the scoops on my

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  17. dastang2

    dastang2 Active Member

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    yes they can be built but it's expensive and stock they suck. the winsdor family are alright performers stock
     
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  18. muh'stang

    muh'stang If I were rich, I'd make sure all the scoops on my

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    its not that expensive. You get a serious cost break on initial purchase, most people give them away. A timing chain, new pistons, ported heads, cam and intake will get you burnin rubber easily....I wasnt flamin you for calling it a boat anchor, just rather correcting your statement to read "theyre a boat anchor in stock form" next time you pass on that bit of info.
    The 2 major problems of the M block engines are the pistons are down almost 0.10" below deck, and the cam was retarded 4 degrees.
    Did you listen to the vid? that engine sounds pretty badass
     
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  19. 71swing

    71swing Member

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    351 clev. IS bullet proof.

    My 73 mach 1 with 351 will run high 11's allday, I really beat the crap out of the car at the track and still running strong.

    It is the original block but had been completely rebuilt about 10years ago. Iv'e put about 100passes on it blowing my toploader, drive shafts, and twisting my axles. never had a problem with the motor.

    clevland is basiclly a windsor block with some of the water ports filled in so they could put a modified version of the Boss heads on it.
     
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  20. sbftech

    sbftech Banned

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    The cleveland is far from a windsor block. What do they share? Bore spacing! Clevelands are far from bulletproof. And Im a cleveland junky. Why do you think we all took windsor blocks in the 80's and used cleveland heads on them?
     
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