Yes M stands for modified. You dont see M after the 400 which is the same block.

 

>Yes M stands for modified. You dont see M after the 400
>which is the same block.

Well first of all Ford only made 1 400 as opposed to 3 351s so that's why there's no M after it. Second, the 400 came out 4 years before the 351M so if Ford were going to have the M stand for modified then why didn't they call it a 400 Modified Cleveland?

 

Because as you said Ford only made 1 400 so there was no need to at that time. Then when whey started making another 351 there was a need.

 

The m stands for Modified. The 351m is a 351 big block with 2v clevo heads thus being called modified


82' Flareside with 400 horse under the hood

 

oh my, this is gonna be fun

 

[updated:LAST EDITED ON 17-Dec-01 AT 11:59 AM (EST)]>The m stands for Modified. The 351m is a 351 big block
>with 2v clevo heads thus being called modified

I really wish this thread would just die.

OK, first of all the M could very well stand for Modified. The trouble is that nobody can find any factory documentation from Ford so nobody really knows for sure. All we have is a bunch of hearsay evidence like "Well all the parts guys call it that." Second, you can't really fit the 335 series into the standard "big block/small block" model. The 335 series includes the 351C, 351M and 400. The C has the same bore, stroke, bore spacing and bellhousing bolt pattern as the 351W which everybody "knows" is a "small block". The 351M has the identical stroke, bore and bore spacing but the BH bolt pattern of the 429/460 and the block is almost as tall as the 385s. The 400 is the same motor with a 4" stroke. Finally, while the 2V C heads are very close, the M has it's own heads which differ slightly in the exhaust ports. 2V C heads will certainly fit a M and vice versa but then so will 4V C heads and they are definitely different. With minor modifications, Cleveland heads will also fit on a W motor.

 

I can clear this up a little bit for you guys. The only thing ford has called the 351 with a 10.297 deck height is simply "M". That is it. And the only reason anyone ever called it anything else is so they don't sound stupid. Have you ever walked into a parts store and asked for a set of spark plugs for a 351 "W" or 351 "C"? No. You would say "Windsor" or "Cleveland". Hence some people say "Modified" or "Michigan" or "(insert word starting with M here)".

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I know I'am a newbie to this forum , so nobody will give credit to what I say but here it goes anyway .

The Mdoes stand for modified , but the modification was to create a hermaphrodite motor .

There where two "cleveland" style blocks , the 351 cu in. and the 400 cu in. , period dot end of story .

Ford didn't create the 351M because they wanted to , they created it because the windsor plant couldn't keep up with the demand for the 351 motor . So ford decided to MODIFY the 400 by installing the 351 windsor crankshaft into it . Nobody was buying the 400 so they had the ability to help with the demand for the 351 .

 

>I know I'am a newbie to this forum , so nobody will give
>credit to what I say but here it goes anyway .
>
>The Mdoes stand for modified , but the modification was to
>create a hermaphrodite motor .
>
>There where two "cleveland" style blocks , the 351 cu in.
>and the 400 cu in. , period dot end of story .
>
>Ford didn't create the 351M because they wanted to , they
>created it because the windsor plant couldn't keep up with
>the demand for the 351 motor . So ford decided to MODIFY the
>400 by installing the 351 windsor crankshaft into it .
>Nobody was buying the 400 so they had the ability to help
>with the demand for the 351 .

It's not a matter of whether or not you're new to the forum, any accurate information is welcome. While it's true that there were only 2 blocks made, the 351M is not a 400 with a 351W crank in it. While they are similar, the M crank and the W crank are not identical, different castings, different counter-weights, different snouts. They also had to make unique pistons for the 351M to make up for the increased deck height so that kind of blows the "off the shelf parts" theory out the window.

 

OK, just couldn't resist adding even more wood to the fire. This topic seems to go on forever. I, like benz302, am new to this forum, but have some info for anyone interested. First, Benz302 is very close to the truth. The 400 was first introduced in 1971, the 351M was introduced in 1975. So, the 400 came first. (this is important) Now, when the gas crisis came along, 400 cubes is alot of engine to feed, so it was determined by the Gods of Ford that less cubes means less fuel consumption equaling more sales. You do remember the fuel crisis/gas shortages, right? (ancient history, I suppose). Anyway, rather than changing over every engine bay and transmission configuration already slated for construction, thinking of just trucks for now, it was determined that the 351 Windsor crankshaft (main journal: 3.000 inches, rod journal: 2.311 inches) could be utilised in a 400 block (main journal: 2.998 inches, rod journal: 2.3107 inches) and use the existing 400 connecting rod (length of 6.58 inches) and only have to manufacture a new set of pistons. Now, please understand, it is infinitely easier and cheaper to produce on new line of pistons than change out an entire engine bay, not to mention the increase in demand for an engine (the 351 Windsor) in another plant miles away, meaning the engines would have to be shipped (more cost). So, now the Ford Motor Company has 3 engines displacing the same amount of cubes, the 351 Cleveland, made in Cleveland, of course, the 351 Windsor, made where? Oh yeah, Windsor, ontario, Canada, and now a hybrid made (technically) in both plants. The 351M is a designation for a "MODIFIED 400", or a de-stroked 400. Thus the confusion, 351M or 400M. Everyone still with me? (looks into crowd, still sees a lot of blank stares...)
Anyway, i hope this helps clear this up for you guys who are just dying to know. Oh, one other thing: There was a rumor about an over-run in 351 Windsor crankshaft production at the time. This MAY have sparked the idea of what to do about needing a smaller displacement engine AND what the hell are we gonna do with all these extra cranks!?!?!?

 

[updated:LAST EDITED ON 01-Feb-02 AT 04:01 AM (EST)]What a bunch of crap. As a new FTE member who just purchased a '79 F-250 I was very excited to find this site, and then specifically this message board - UNTIL NOW. You guys are friggin ridiculous. I have never seen this kind of worthless conversation before on a automotive m-board or mailing list. Meanwhile a very simple question I posted 10 hours ago is still sitting there with zero replies, while this stupid thread has over fifty. I thought the endless rants of Jeep CJ vs Wrangler were bad in my previous experiences, but squabbling over what a single letter means that none of you have any evidence to back up is insane. I'm thinking about swapping this 351M out for a 460 now instead up building it as a 400 just so I can follow the big block board. Or maybe I'll drop in a non-Ford motor just to spite you all. Worthless.

 

[updated:LAST EDITED ON 01-Feb-02 AT 12:55 PM (EST)]>What a bunch of crap. As a new FTE member who just
>purchased a '79 F-250 I was very excited to find this site,
>and then specifically this message board - UNTIL NOW. You
>guys are friggin ridiculous. I have never seen this kind of
>worthless conversation before on a automotive m-board or
>mailing list. Meanwhile a very simple question I posted 10
>hours ago is still sitting there with zero replies, while
>this stupid thread has over fifty. I thought the endless
>rants of Jeep CJ vs Wrangler were bad in my previous
>experiences, but squabbling over what a single letter means
>that none of you have any evidence to back up is insane.
>I'm thinking about swapping this 351M out for a 460 now
>instead up building it as a 400 just so I can follow the big
>block board. Or maybe I'll drop in a non-Ford motor just to
>spite you all. Worthless.

A couple of things here. First of all this discussion is completely relevant to this topic. Second your question has been answered despite the fact that it's rather vague. Are you turning your 351M into a 400 or are you simply rebuilding your 351M?

Insulting the people on this board because they didn't answer your question in as timely a manner as you would have liked is probably not a good way to get an answer.

If you don't like the contents of a thread then don't read it. It's really just that simple.

 

Sorry Folks, but I should correct myself or make something clearer at the very least: The 351 Windsor cranks in and of themselves were not used to make the 400 into a 351, it was the moldings and toolings used with minor modifications. The molds were altered slightly for larger counterweights, but that was cheaper than starting with a whole new mold and all new tooling. This was for cost/budgeting reasons. Th3e same went for the 351M's pistons: Ford already had tooling set up for a "cleveland" style piston, just alter the existing platform for a longer compression height, or pin height, as some may know it. This way, again, noneed to design an all new piston with all new tooling. Basic manufacturing thinking......

 

This excerpt from the Project Bronco Site.

The “M”, by the way, does not stand for anything. Ford only used the “M” designation to distinguish it from the 351 W (Windsor) and the now discontinued 351C (Cleveland). The “M” designation has now become know to mean “modified” or “Michigan”, even though the 351M was produced at both the Cleveland foundry and Michigan casting center.



Dennis



Please Don't Ask Me Any Tough Questions As:
"I'm Saving My Memory For When I Develop Alzheimer's"


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78-Buick LeSabre 403 4V
84 Volvo DL Wagon

 

I'd hate to get this all stirred up again, but I have to agree with Dennis and Bill. I was raised in a predominantly Ford family. All that I heard growing up was Ford and I always heard 351 Modified. However, now that I'm older, and as I've read every word of this prepostourus yet amusing thread, I can't ever recall Ford calling it a Modified. I now call it a 351M. I've seen Ford print Boss 351, 351 Windsor, 351 Cleveland, and 351M. The Boss 351 had a Cleveland block, incase somebody was waiting to jump on me for not mentioning that. Tomorrow I'm going to call FoMoCo, that's Ford Motor Company, for those new guys, and hopefully find a reliable source who can end all of this madness by hopefully finding documentation at the Ford archives as to what the M stands for and hopefully be kind enough to post it here. Surely he would own a Ford Truck, don't you think?

Now let's all stop ,and ,and , and realize that together we have a lot of knowledge here at FTE. If somebody has a question, at least one person here has the answer. There are things that we had problems with on our trucks that somebody else is experiencing right now. Let's not get into these meaningless arguments about an engine designator. By the time I'm finished building by 351M the M will stand for MONSTER! But I seriously doubt that's what FoMoCo will be calling it. Now let's all go four wheelin'!