On 2005-12-08 17:49, Lazarus Project wrote:
The housing for the timing chain/gears on the 351C is cast into the block where as the 351W has a removeable housing much like the 302, IIRC. 351M and C valve covers are the same. 351W valve covers share with 302s. Someone much more educated can tell you the difference between the M and Cs as I don't have a clue.
A 351 Windsor is the 5.8 (351) engine that is found in all Ford trucks from approximately 1983-1997. It was found in various Ford cars from 1969-1991, as well (in latter years, the only production cars Ford ever put it in were Police issue Crown Victorias). It, basically, is a tall-deck version of the 221/260/289/302, and slightly wider, as well. Those engines have an 8.2" deck height. The 351 Windsor, from '69-'71, had a 9.2" deck height. From '72-'97, the blocks had a 9.5" deck height. They use in-line valve cylinder heads...the 221/260/289/302 uses 7/16" cylinder head bolts, the 351W used 1/2" cylinder head bolts. A 351W has a 4.000" bore, 3.500" stroke, and the crankshaft has 3.000" main bearing journals. These large of main bearing journals are good for truck engines, but have proven to be somewhat problematic for high rpm performance applications, because with oiling system the 351W incorporates, even with a high volume pump, it's difficult to get enough oil to that large of surface area at high rpm. I'm talking sustained rpms in the 6200+ range. Most people, when looking under the hood of a truck/car, would have a hard time telling a 351W apart from a 221/260/289/302...they're about identical, other than the fact that the 351W is a little taller and wider. The easiest thing to look at is the width (in terms of distance between cylinder heads) of the intake manifold to figure out if the engine is a 351W or not. A 351W intake is about an inch to an inch and a half wider.
The 351C (Cleveland) and 351M/400 (most commonly referred to as "Modified") are very similar engines...they are the engines that make up the "335" series of Ford engines. Basically, the 351M/400 is a tall-deck version of a 351C. A 351C is considered by most Ford enthusiasts as a "smallblock" because it shares the same bellhousing as the Windsor family of engines (221/260/289/302/351W). A 351C uses splayed valve heads (similar to a 370/429/460 Ford or a bigblock Chevrolet) and various 351Cs can be found with 2V ("2 barrel") open chamber heads, 2V closed chamber heads, or (pretty rare) 4V closed chamber heads. A 351C has a 4.000" bore, 3.500" stroke, and 2.750" main bearings. The Cleveland, years ago, used to be the more common smallblock Ford engine found in Ford race cars at the dragstrip because it tended to be better suited to turn more rpm safely (due to a better oiling system and the smaller 2.750" main bearings) and the stock 351C crankshafts were of a harder material than the cast iron Windsor crankshafts...plus the 351C cylinder heads, years ago, were far and above better suited to performance applications than any production Windsor head. The popularity of the 5.0 Mustang, though, has negated that...the last 20 years has seen more development of the Windsor Ford family of engine (via aftermarket parts) than probably any production ever, in such a short period of time, smallblock Chevrolet included. The 351C was only found in cars (if you don't consider the Ranchero a "truck"...it was based on the Torino in the '70s).
The 351M/400 uses the same cylinder heads as a 351C...however only the 2V open chamber heads, if my memory serves me correctly. The average individual would have a hard time telling the difference between a 351C and a 351M/400 under the hood of a car or truck, for the same reasons I mentioned about a 221/260/289/302 and a 351W. Technically, the 400 was never designated as a "400M", though you'll see folks reference it as a 400M from time to time. The 351M and 400 share the same block. They use a 4.000" bore and a 3.000" main bearing. However, the 351M uses a 3.500" stroke whereas the 400 uses a 4.000" stroke. They share the same bellhousing as the 370/429/460 Ford. The 351M was found in cars and trucks...the 400 was only found in trucks, I believe. They are decent motors and can be built to make good power, but they have known oiling deficiencies...get in a truck or car with a 351M/400 in it that has some mileage (75k+ miles) on it, and more times than not, after the oil gets hot, you'll hear some bottom end (main bearing or connecting rod) knock. The oiling problems can be resolved, fairly easily, during a rebuild. The aftermarket is fairly limited for these engines, though.
EDIT: some folks call the 351M/400 a "big block" engine. I'm not advocating that it is or that it is not. With respect to the actual design of the engine, like I said, it's basically a tall-deck version of a Cleveland (351C), which most engine builders/Ford enthusiasts consider a smallblock Ford. However, as I mentioned, the 351M/400 shares the same bellhousing pattern as the 385-series Fords (370/429/460) and, for that reason, I guess, is why some people call it a bigblock. It's a bit of a maverick, in my book. Dedenbear, JW, etc., cast aluminum bellhousings to mount a C4 behind a 429/460, but they're expensive. If you can find one, Ford put C4s behind some 351Ms in some of the passenger cars in the '70s and the bellhousing from those trannies will allow you to bolt a C4 up behind a bigblock 429/460. Some of the guys that read this probably cringe and think there's no way a C4 would stand up behind a bigblock. A C4 is a pretty stout little tranny and can be built to withstand quite a bit of power and abuse. A lot of guys in 3100 + lb Mustang drag cars running mid to high 8 second quarter miles (putting 800-900+ lb/ft of torque through the drivetrain) run built C4s. I pass this along just in the event somebody reading this might ever have a project car or buggie and wanna run a bigblock/C4 combination. You don't have to shell out the $$$ for an aftermarket piece...however, having said that, a stock C4 bell from behind a 351M is getting hard to find. A C4 is a LOT lighter (and, as such, has significantly less rotating mass) and physically smaller tranny than is a C6.