351w, 351c, 351m engine block and transmission differences? - Ford Mustang Forum

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post #1 of 5 (permalink) Old 12-17-2008
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Question 351w, 351c, 351m engine block and transmission differences?

I need facts on the 351w, 351c and 351m bellhousing patterns and block differences. And also on transmissions that will work with either or all. Im being told a few different things and every where else I look for information is always something different or someone putting their own twist on it. Does the 351c have "bigblock" or "smallblock" pattern? What pattern does the 351c match? Does the 351w have the same pattern? What transmissions will work with all 3 and/or interchange? Any information on this or related information, that can be backed with a good source please let me know. Or if anyone has good links. I may just have to go buy a book, but ill try the internet again.

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post #2 of 5 (permalink) Old 12-17-2008
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I do believe the windsor tranny pattern may fit the cleveland. The Cleveland is a small block pattern as the 351m and 400 are the big block pattern. Don't quote me on the small block pattern but if they are the same they do use a different flexplate. Hot motor right now is the 400m small ford.
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hope you find your info !!!

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post #3 of 5 (permalink) Old 12-17-2008
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The 351W and 351C use the small block bellhousing bolt pattern. The 351M and 400 use the big block bolt pattern.

The C4 auto trans, which has a separate bell, can be used, but you'll probably have to go with an aftermarket bell for the big block pattern. The C4 has two different designs. One is a case fill, as used on Mustangs. The bell uses the trans pump bolts to secure it to the housing and the dipstick is in the trans housing. A 157 tooth flexplate and a converter with a 10 1/2" bolt pattern is used on vintage Mustangs.

The other is a pan fill, the dipstick is in the oil pan and it has separate bolts to secure the bell to the housing. This is a stronger and larger unit and was used in full sized cars and trucks. The flexplate is a 164 tooth and the converter has an 11 1/2" bolt pattern. The bells are not interchangable between the two designs.

Case fill bells with can be found that use both the large and small F/P and converter. The bell is deeper with the larger F/P and converter, though. The pan fill only uses the larger ones. You will have to consult the aftermarket as to which type C4 is used with the big block pattern.

The C6 has a one piece housing and is available in big and small block bolt patterns.

1982 and up 302/5.0 engines only, use a 50 oz imbalance. A Mustang 157T F/P with 50 oz and 10 1/2" bolt pattern is an aftermarket piece since no C4s with this imbalance factor were factory installed on these later engines. All of the other engines use a 28oz imbalance F/P throughout.
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post #4 of 5 (permalink) Old 12-18-2008
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The 351W and the 351C is a small block. And the 351M/400 is a big block that was used it trucks. As a matter of the 351W/C also share the same tranny as the 302. Barnes and Noble has some of the best books on them.
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post #5 of 5 (permalink) Old 12-18-2008
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They made a c6 for a big block and small block can't remember if the bell housing came off the c6 or not.What engine and tranny are you trying to use?
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