howdy,
im new to the 351m i have always known 351ws. what kind of hp does a 351m put out stock with the 2bbl intake and carb? whats the diffrence between a 351m and a 351c?

 

351M uses same block as 400 so has taller deck than Cleveland. You can use search on this site for a bunch of info on the engines.

 

Check this out:
High Performance Options for the 351M/400 Engine by Dave Resch

 

Contrary to popular belief the 351m, stands for modified, meaning that it is a 400 with a slightly shorter stroke. The above post was correct. I have rebuilt tons of 351 m's, and i don't really concern myself with horsepower. it is a product of the late 70's emissions fiasco, and is better suited for longevity than performance. It is not a speed demon, or torque monster, but if they are built right, they make a fine truck motor, that is reliable, and works hard. If you want to go fast build a 351 cleaveland or windsor, which are two completly different motors. none of the 351's are remotly similar, but a little intellingence, and care they are all three good engines.

 

Not "remotely similar" is misleading. All three 351 CID engines (I'm not talking about the 352 FE) have the same bore & stroke 4.0" X 3.5". They also have the same bore spacing and with some modifications the heads will interchange on all 3. The heads of the 351C and M will interchage with no modifications whatsoever. Although the W is from a different family the 351C and M are both from the 335 series and there are a lot of parts which will interchange besides the heads...cam, timing set, distributor, oil pan & water pump just to name a few.

 

Yes there are parts inculding cylinder heads that will interchange between the 351c and m, but they are still two seperate motors, and I don't like mis-matching parts between the two. the modifieds extended deck clearence, much like the 400 can lead to excessive pinging and detonation problems if it is not built right, while that problem is non-existent is the cleveland, it has problems of its own like, like its oiling system for example. I am a fan of all of the 351's but they all have their place, and they are all tempramental.

 

Well the 2V Cleveland heads are virtually identical to the M heads so there shouldn't be any mismatch issues. The deck clearance issue is really only applicable to the 400 regardless of which heads you have on it because it's a piston/block issue not a head issue. Open chamber heads are more prone to detonation...period, and with the exception of some early closed chamber 4V heads all C and M heads are open chamber.

 

That's true, the closed chamber heads are happy, especially with deck clearance set close to zero. With right cam one can run quite a bit more compression than the open chambers. Previous was correct also about the oiling on the Clevelands, probably applies to all of them, though. With a little work & good oil they work fine.

 

the 351m/400 have virtually the same oiling system as the 351c thus the 351m also has oiling system problems, and BTW they oiling system on these engines is almost identical to the 429/460 engines with the exception of the Boss 9 which had priority oiling to the mains. the open chamber cleveland heads both 2v, and 4v also had detonation problems if you bumped the compression up also the 351c, and the 351m both had 3.5" stroke, and a 4" pistons so they are actually quite similar on alot of things, and the heads are the same so swapping them is no problem.

 

I have yet to encounter oiling system problems on the 351m, however the 351c has a nasty habit starving the bottom end of the motor at higher rpm's, with can easily be prevented with some machining. I also want to clear something up, when I said i don't like to mismatch parts, I did not mean that It can't be done, or it isn't a good idea, I am just picky when I build things. Also, the above was correct in saying that the 400 had more issues with the deck clearence than the 351m, but even so, it can become a problem with a careless rebuild. 351's and 300-6's are my favorite of the ford truck motors, and i have spent most of my life around them. most guys go for mind blowing horsepower, which is fine, i can understand that, but I go for longevity. its all in what you want. I think that all of them make excellent truck motors. the cleveland is more suited for muscle car power, but it can be done. I've never had any trouble with any of the trucks that I have rebuilt for other people. they were all good trucks.

 

you are correct in that the 351c has a problem with staring the bottom end at high rpms mainly when you run a hi volume oil pump becuase it ends up putting all the oil into the valve covers, the thing is a 351m has exactly the same oiling system, and will do exactly the same thing if you are twisting it 7000rpm, but most 351m don't twist that hard, and were never intended to. A cleveland running below 5000 all the time will never have an oiling problem either, and both of them can be cured with restrictors, and/or restrictor pushrods, plus you can put fast drain back tubes in the heads to the oil pan, and run a bypass line to the backof the block which help also.
As to your other comment I agree that the 300-I6 is one of the best truck engines built I have had a couple of them and they outpulled my big block chebbie, and my 460 at low end hands down, it was a sad day for me when ford did away with that engine. Personally I don't care for any of the 351s for a truck engine. And yes I ran a cleveland in my 88 ranger but that truck was never intended to be a work truck it is race only, and that is a good place for the C engines.

 

That makes sense. Now that I think about it, the oiling system from both engines did seem familiar, but I have only rebuilt a couple of c's (with restricters), I have never taken the m up to rpm's that high, so i guess that is why i have never encountered that problem! I grew up on a farm, with lots and lots of machinery, and now I am an aircraft mechanic in the airforce, so i have always been taught to respect machinery, and not abuse it. i like my 300 more than the 351's, but i have restored tons of 77-79 fords with the 351m, and every one of those trucks that i built are still on the road today. other engines do LOTS better on fuel, and torque, but my engines have proven themselves to be reliable and quiet, and a simple pleasure to drive. I take a lot of pride in my work, and most people that buy my trucks know that. They are not wild horsepower machines, but they are comfortable, reliable transportation that you can depend on. and that's really what i concern myself with.