351M anyone know much about 'em

[Bear in the woods]

Found one and was wanting to know the good,bad,and the ugly.
rare? Expensive to work on?
TOO MUCH FOR A 90 RANGER

 

[rubydist]

That is basically a 351C with a block that has the big block bellhousing pattern. 351M heads are like 351C 2V heads except they have hardened seats so you can run unleaded without issues.
Fitting a big block transmission in a Ranger is going to be a real challenge. Also, the 351C/M is physically larger than a 351W (which takes a bit of work to fit in a Ranger), so while anything can be done with enough time and money, fitting that into a Ranger is going to be a lot of work.

 

[pjtoledo]

they have taller decks than a 351C. need their own intake manifolds or at least spacers.
a simple crank & piston swap puts them at 400ci, if you can find a crank.
one of the car shows built one to 600 hp, Engine Power???

check it for head cracks.

 

[rusty ol ranger]

Not a bad engine.

Not rare by any means. Dime a dozen because a 460 is a direct bolt in replacement.

Early 77 castings had block crack issues. Those are probably all dead by now.

Not the stoutest power wise...150ish hp and around 290ish ftlb (dont remember exactly), but its all down low and useable.

Uses the 385 series (429/460) bellhousing pattern and motormounts.

You can wake them up considerably with a cam, intake, 4bbl, headers, and straight up timing set.

They are easy to stroke up to a 400 (literally just buy a 400 crank and rods) this buys you about 1/2 in more of stroke, coupled with the above mods, they are solid truck engines.

BUT...in a ranger...i wouldnt bother. Its possible, but they are physically bigger then a 302/351w. Power output stock for stock is about like a W (athough the M seems to be more torquey down low, W strings out more), and a 302/351W has alot more aftermarket and overall potential.

If you had a older fullsize and wanted to build a stout DD/towrig id say go for it (personally i like the 400 more then the 460, which, a 351M is a destroked 400, which is why i mentioned building it with 400 internals), but in a ranger a windsor or 302 is a better option

 

[don4331]

As noted the 351M is the "tall" deck of the 335 family; while 351C is the "short" deck

302 (Windsor) 8.2" from crankshaft centerline to head deck​

351C 9.2" which coincidentally is the same as small block Chevy​

351W 9.5"​

351M 10.2" The same block is used for the 400, just 4" stroke instead of 3.5" one.​

​

So, the 351M block is ~3" wider than a 302. All that extra width is cast iron - 351W is 75 lbs more than 302, 351M is 75lbs more than 351W.

It might be getting rare now, but it was a common smog motor back in the 80s. As it was a smog motor, it has very low compression & mild cam i.e. heads with very small ports/open chambers - the one plus is hardened valve seats so it handled unleaded.

There were never any factory hi output versions - even a factory 4 bbl intake is going to be rare (if it even exists, I've only ever seen 2 bbls). Spacers were used to fit 351C 4V intake/heads. But 351C 4V heads really had too small heads for pump gasoline, so you needed dished pistons too (preferably bathtub, so you still got proper quench). As a result of the amount of change required for simple hop up and the extra weight, the aftermarket really didn't cater to it.

The transmission bolt pattern is same as 385 family (429/460 aka 7.6). (I think of FE family as big blocks too, and they have separate bolt pattern...thanks Ford).

They can be built to make decent power, but you're manufacturing a lot of your own part = expensive.

 

[Bear in the woods]

Thanks y’all. Run across one for $500. Was just wondering if it was something I should get

 

[rusty ol ranger]

Thanks y’all. Run across one for $500. Was just wondering if it was something I should get

For 500? No.

I just bought a running 351W for 450.

M's usually bring 150-200 bucks around here. 250-300 for a 400. In running shape.

 

[Bear in the woods]

Thanks. Always see 351w and 351c I haven’t saw m many times. Figured I should check before I let it pass

 

[pjtoledo]

For 500? No.

I just bought a running 351W for 450.

M's usually bring 150-200 bucks around here. 250-300 for a 400. In running shape.

I'm looking & listening. car/part doesn't show any.
I have a running 351M that I might consider throwing a 400 crank in. plus a few other goodies.

 

[rusty ol ranger]

I'm looking & listening. car/part doesn't show any.
I have a running 351M that I might consider throwing a 400 crank in. plus a few other goodies.

Im guessing most have been extinguished from junkyards.

FB marketplace usually has a decent amount of them though. Atleaat last time i looked.

I had a 78 F350 with a 400 that had the mods i mentioned above. Coupled with a T18 4 speed. That truck was an absolute monster.

If there was a logical way to do it next time the 460 in my 97 takes a dump id put a 400 in.

You got a chassis in mind for it or just wanna do it for the hell of it?

 

[franklin2]

There were never any factory hi output versions - even a factory 4 bbl intake is going to be rare (if it even exists, I've only ever seen 2 bbls).

Factory 4bbl intake for a 351m or a 400 doesn't exist. They were all 2bbls from the factory. If you see one with a 4bbl carb on it, the intake is aftermarket.

 

[rusty ol ranger]

Factory 4bbl intake for a 351m or a 400 doesn't exist. They were all 2bbls from the factory. If you see one with a 4bbl carb on it, the intake is aftermarket.

Actually...

There are a few factory 400 4bbl manifolds from the very early 70's.

I found a picture of one online a few years ago.nSo take it for what its worth. It could of very well been a 460 manifold.

But for all intents and purposes they were all 2bbl

 

[19Walt93]

Actually...

There are a few factory 400 4bbl manifolds from the very early 70's.

I found a picture of one online a few years ago.nSo take it for what its worth. It could of very well been a 460 manifold.

But for all intents and purposes they were all 2bbl

Nope, no 400's got 4 barrel carbs from the factory.

 

[Shran]

If there was a logical way to do it next time the 460 in my 97 takes a dump id put a 400 in.

Aftermarket transmission controller should have you all fixed up... the hard part of doing a 351M/400 to 460 swap was clutch components and motor mounts, I think (been a few years since we did one) but going the opposite way should be pretty easy. I think I'm with you, I would rather have a built 400 than any stock 460.

This topic reminds me that I've seen a couple Super Duties with 300 six and 6.9 IDI's swapped in... kind of hilarious really.

 

[19Walt93]

I worked on a bunch of 351M's and 400's. Up through early 77, the intake valley walls were flat and prone to cracking which allowed coolant to slowly leak into the oil. The later, improved block had wavy walls and I never saw one crack. I changed a bunch of blocks under warranty. As mentioned, swapping in a 400 crank and pistons turns a 351M into a 400. If you already own a 351M or 400, they weren't bad engines- just bulky and heavy. Recurving the centrifugal advance from anything built in the mid/late 70's will make a dramatic improvement.
Because of their size and weight, I wouldn't use a 351M/400, a later roller cam 302 or 351w would be my first choice.
We had great luck with the 429/460 engines, other than a timing chain and probably some valve cover gaskets, I never took one apart. The late 70's 460's came with a Motorcraft 4300 carb- basically a Quadrajet- that had a bunch of driveability issues that were cured by ordering a single part number from a TSB. It got you a Holley and the parts to install it. I would never think of swapping a 400 in place of a 460. Unless the 460 blew up and I owned a good 400- NH yankees hate to spend money.