Skinny on the 351

[Detector]

So what is the skinny on the 351? My 1971 Grande decodes to have had a 351 2V(H) and I'm being told it would have been a 351C. A search on the Internet gave some information but I'm still confused about some of it.

I read in 1971 they didn't make the 351W thats why my mustang would have had the 351C, but I'm still missing some of the difference between the two. Did the 1971 351C have the same block as the 351W? Was it a small block? I read that the 351M from 1975 was the big block like the 400. What are the advantages, if any, of the 1971 351C over the 351W?

The big question is would it be true that my 1971 would have had the 351C?

Thanks

 

[Hack]

The 351W and the 351C have different deck heights. The 351C is 9.2" and the W is 9.5 (mostly). So different blocks.

The Cleveland was built for performance, and the Windsor was designed for truck/passenger car use. The Cleveland type architecture is still used in Nascar, although Ford is finally designing a new motor for Nascar now.

The Clevelands have canted valves to improve breathing in performance situations. The Clevelands do not send water through the intake manifold in order to keep the intake charge cooler. Clevelands have smaller mains for better high rpm performance. There are other differences, but those are the big ones.

If you follow the Engine Masters competition by Popular Hot Rodding, the Cleveland type engines with CHI aluminum heads win and place high almost every year (shows the superior potential of the Cleveland). Nowadays you can get plenty of performance heads for 351W that work great - the main thing is if you want to use stock style cast iron heads the 351C has a big advantage over the 351W. Most performance minded builds use the 4V heads, but you can make 500 hp with the 2V heads. I personally would not use 2V heads, because I always get used to the power my engine is making and then I want more. 4V heads give more room to grow in power.

I think you're right about the W not being installed in '71 Mustangs. Once Ford released the Cleveland in 1970, they stopped putting the 351W in the Mustang (performance application).

 

[RogerC62]

The two are visably different when looking under the hood.

Fuel pump mounting:
351W = 2 bolts in horizontal
351C = 2 bolts in vertical

Thermostat
351W = housing attaches horizontally to intake manifold
351C = housing attaches vertically to top of timing housing cast into block

Rocker covers
351W = 6 bolts
351C = 8 bolts

 

[golf4283]

the 351c is considered more a part of the big block family of engines whereas the Windsor is part of the small block family.

The 351C is generally a heavier engine and the 351W is lighter due to it's small block design.

Both engines can be made to perform excellently so you really can't go wrong.

 

[Hack]

the 351c is considered more a part of the big block family of engines whereas the Windsor is part of the small block family.

The 351C is generally a heavier engine and the 351W is lighter due to it's small block design.

Both engines can be made to perform excellently so you really can't go wrong.

The 351C is a SMALL BLOCK. It has a lower deck height than the 351W. The bore spacing is identical to the 351W. The transmission mounting pattern and motor mounts are also the same as the other small block Fords.

The Cleveland weight is similar to a 351W. The lower deck partially makes up for the cast-in timing cover and larger heads. I think the difference in weight is 50 lbs or less IIRC.

Chevy guys like to call it a big block because it makes too much power compared to the SBC.

 

[bnickel]

i will add that clevelands don't have the best oiling system, it's adequate for street and mild performance applications but for a high performance app, i would do some modifications, actually if it were me i'd do the oiling system mods on even a street engine. clevelands tend to have very thin wall blocks and really bad core shift problems which will make one part of the cylinder thicker and one side thinner, they also have problems with the stock rods not being very strong. having experienced all of the clevelands shortcomings personally i can attest that it's not an old wive's tale or some internet myth either. i love the cleveland heads but everything under them needs some improvement, whereas the windsor is a great engine other than the semi-crappy stock heads

 

[SadbutTrue]

The 351C is a SMALL BLOCK. It has a lower deck height than the 351W. The bore spacing is identical to the 351W. The transmission mounting pattern and motor mounts are also the same as the other small block Fords.

The Cleveland weight is similar to a 351W. The lower deck partially makes up for the cast-in timing cover and larger heads. I think the difference in weight is 50 lbs or less IIRC.

Chevy guys like to call it a big block because it makes too much power compared to the SBC.

Actually I've always called the 351C a small big block and the 351w a big small block as well. Actual deck height, displacement and size aren't necessarily what defines that for me.. after all, there are plenty examples of single engine families with the same size block spanning both small and big block displacements (SBC, Pontiacs, etc).

The main thing are the heads. Basically copied BBC heads, if what i've heard is correct.

That, and the engine family that it is part of (the 335) goes from 351-400 cid (as I believe the 351M and 400 are related to the Cleveland, moreso than any other engine anyway).

Most small block engine families start in the 200s somewhere, whereas most big bloc engine families (including big block chevies and chryslers, as well as the ford FE family) start in the mid-to-high 300 cids and go from there. The Clevelands family profile is much more in-line with the latter.

In these areas, the Cleveland has a lto more in common with the big block than the small block.

 

[Hack]

I always hate when Cleveland questions come up on this forum because the myths and misconceptions come out of the woodwork. Here's a link to a forum with many guys who know a lot more than me. I go there to learn about the Cleveland.

Ford 335 "Cleveland" Series Engine Forum

I have to agree somewhat with Bnickel - he's very knowledgable. However, the non-specific way the post is written it could scare many people off from building a Cleveland. If you are going to rev the Cleveland higher than 7,000 to 7,500 on a regular basis and hold the revs up there you will want to pay special attention to oiling. It's a good idea to be careful about how the lifters fit in the block, because the Cleveland does not have a priority main oiling system.

People also talk about core shift too. It's a good idea on any performance build to keep as much material in the engine block as possible. If you're boring more than 0.030" over you should have the block sonic checked first, especially if you're going for a lot of power.

The problem as I see it is that the Cleveland came with genuine high performance heads straight from Ford, so people were able to test its limits. The Windsor engines (other than the Boss 302 with its Cleveland heads) always were forced to breathe through a straw from the factory.

Low performance engines are often dead reliable. The Cleveland, especially the 4V versions, are not low performance like the 302 and 351W always were from the factory. If you build a Cleveland properly it will make huge power. Below is a link to an article about an engine making 760 HP with cast iron Cleveland heads.

Parker Racing Components - Pantera Magazine article

 

[bnickel]

the cleveland and the windsor are both small block engines not related to big blocks at all, yes the cleveland has canted valves like some bi block engines but these heads were first used on the Boss 302 engine and the boss 302 is most definitely NOT a big block. if you were to build a 351 clevor engine using a 351w block and cleveland heads would that also be a big block? i don't think so, personally.

as for the 351m/400 motors they have qualities of both big and small block engines but they are basically just a small block too, though most of them did use big block bellhousing and motor mount patterns however some 400 engines used the small block bellhousing and engine mount patterns too...no actual big block ever did that. also quite a few passenger car 351m/400 engines still used the FMX transmission which was built for the larger displacement small blocks and they had the FMX with both bellhousing bolt patterns for the 351m/400 engines as well.

on to the points about the cleveland myths, while it's true there are many myths and misunderstandings about the cleveland, especially when it comes to oiling system and core shift there definite issues there. it's true that most of the time they are blown out of proportion, however all myths are somewhat based in fact and i can tell you from experience that even standard bore 2v clevies can have both problems. for instance the original standard bore 2v clevie in my old 70 cougar had both problems and it wasn't until the oiling problem reared it's ugly head that i found about them when i was on the highway heading home from school one day. i was driving along at around 55-60 mph (standard 3.00 rear gears BTW) when i heard a loud bang and the car started losing power, i was able to coax it home by keeping my foot on the floor and not stopping if i could avoid it. when we tore it down we found that the rods on #1 and #5 cylinders were snapped at the big end and the big ends were welded to the crank, this is the weakest link in the cleveland oiling system too, and the cylinder was split and it couldn't have been more than .080-.090" thick where it split but when we knocked a chunk out of it to see how bad the core shift really was it was almost 3/16" thick on the other side of the cylinder from where the split was. that's some serious core shift if you ask me. had it not been for that we probably would have been able to rebuild the engine. the only mods that had ever been done to that engine were the addittion of a performer intake and 600 holley other than that the valve covers had never even been off and it was a fairly low mileage engine too with only about 80,000 miles on it.

 

[D.Hearne]

The big block relation stems from the fact that the heads are basically downsized 429/460 designs. And those were improvements to Chevy's 427 heads opon which they were based.

 

[jlangholzj]

also I know this has been pointed out to me that the valves on the 351C (don't know on the W) are of a two piece design. it would be a good idea to get a new set of those otherwise your engine might possibly eat a valve

 

[69gmachine]

Big block and small block are Chevy terminology. You just can't put Ford in a box like that. If you like the Cleveland, build one. If you like the Windsor, build one. There's easy off the shelf power for almost every Ford engine ever made now.

Once upon a time the huge variety of engine design variations from Ford were what kept the aftermarket virtually all Chevy. With the 5.0 coming on strong as the Camaro/Firebird did their swansong, the tables turned. This is the golden age of Ford performance with huge aftermarket support for the Windsors, Clevelands, Clevor hybrids, FE including the ultra rare SOHC, the 385 with not only multiple versions of CJ heads but now 2 aftermarket versions of the Boss 429 heads. Thanks to Jeg's EMC, there are intakes for the 351M/400 that allow the CHI heads to bolt on and make huge power for those engines. Their architecture may not lend itself to the Mustang's bay, but if any engine qualified as a "small big block", the 400M is it.