Does 351M = 351 cleaveland? - Ford F150 Forum

brianwayne · 11-06-2009, 07:54 PM

Hi everyone,
I currently have a 1990 f150 4x4 with a 351, I don't know if it is a cleaveland, winsor, or newer type 351, it is the original motor.
The other day someone offered me a 351M, which he said is a 351 cleaveland.
I was wondering if anybody knows if the motor mounts would be in the same spot or if they would need modifying? Would the transmission belhousing bolts line up or would the transmission need changing? and if so to what?
Thanks in advance for any help or suggestions.
Brian

tleach17 · 11-06-2009, 07:58 PM

The 351 you have is a windsor. It has a small block trans bolt pattern. The 351M has a big block pattern. And no the 351M is not a cleveland. they are totally different. I have heard cleveland heads work on the "m's" with some machining but have never seen it done. The Windsor is a much better motor. Stick with that.

|WYG|SS · 11-06-2009, 07:59 PM

you would have to find out what yours is. cleavlend or windsor. im not sure it the 351m is a cleavlend. i think the 351m is just different than both the c and w, i heard the 351m has a longer stroke.

brianwayne · 11-06-2009, 08:41 PM

I appreciate the responses

brianwayne · 11-06-2009, 08:42 PM

Quote:

Originally Posted by tleach17

The 351 you have is a windsor. It has a small block trans bolt pattern. The 351M has a big block pattern. And no the 351M is not a cleveland. they are totally different. I have heard cleveland heads work on the "m's" with some machining but have never seen it done. The Windsor is a much better motor. Stick with that.

I have been doing more reading and it seems to line up with what you are saying.

dr_bowtie · 11-06-2009, 09:14 PM

there are 3 different 351 engines in Fords line up...the most popular and the one that came as a factory option in your truck is the 351W or Windsor as been posted....

The Windsor line is both the 351 and the 302 engine..these look identical with the only exception being the 351 has a taller deck height so the Intake manifold is 2inches wider than the 302...

the 351M or Modified comes from the Intermediate line up Ford did in the mid to late 70s....this also is combined with the 400M...these 2 are identical also...and are totally different from the Windsor line...

Next is the 351 Cleveland....and it is in a breed of its own..made in the late 60s and early 70s and shares some similarities in the Heads with the Boss 302...

93f-1504x4 · 11-06-2009, 10:29 PM

what makes the 351 modified and the 400 modified, modified? what did ford modify on those? and whats the difference between 351c and 351w?

Khyren · 11-06-2009, 10:57 PM

The M is the modification of the 351C 2bbl to have bigger main journals and a taller deck height for the fitment of the 4" stroke for the 400. The 351M's have the BB bellhousing pattern and have considerably longer rods than the 351C. Now, there is a 302C but that is only in the land down under. Yet on the other side, there are very FEW modifieds that have the SB bellhousing pattern. They called it the 400 FMX. I used to have one. I could go on and on about the 335(I think) engine series but I don't want to leave a huge book here of information. If you have a 1990, 99 out of 100 times you will have a 351W unless someone has purposefully swapped in a 351C.

93f-1504x4 · 11-06-2009, 11:12 PM

cuz my uncle had a 1983 i think with a 351m an he was always talkin that it was a piece of crap.

mitchalvin · 11-07-2009, 06:43 AM

Quote:

Originally Posted by 93f-1504x4

cuz my uncle had a 1983 i think with a 351m an he was always talkin that it was a piece of crap.

You could make power out of these by switching the timing gears for straight up gears instead of retarded gears. The M also tended to have lower compression ratios from the factory.