yeah, you see people everywhere building them.......n/m
Re: 351/400M Engines -- Chris W.	Post Reply	Top of thread	Maverick Message Board

Posted by: Steve H. 12/31/2001, 16:41:50

Some of you people don't know what your talking about. The "M" series motors have the greatest potential of the entire Cleveland family! Maybe of any Ford small block? Not to mention, they are pretty cheap to build. The only problem with them is their large physical demensions. They are almost as large as the 460. With their tall deck, imagine the stroker you could build. The biggest Windsor I've ever seen was a 435 CID. That's with the Windsors 9.5" deck, compare that to the M's slightly over 10" deck. If not a longer stroke, then atleast longer rods. Any stroker crank made for the 351W will work with the 400. Remember, alot of stroker 351W cranks are 400 cores. Also, if you look closely at the bottom end of the "M" engines, thay are cast ready to except 4-bolt mains. As for the Clevelands oiling problems, you pretty much don't have to worry about them. The Clevelands have problems at HIGH RPM's ( over 7000 ). A mildly built 400, even with 4V heads probly still wouldn't go much past 6000 RPM's. 4V headed 400's make lots of mid-range power. Any intake manifold made for the 351C's will work if you use Wieand's adapter plates. Tunnel Rams, Torkers, Performers, etc. In fact, cams, lifters, timing chains/gears, oil pumps, rocker arms, cylinder heads, flexplates, balancers, and distributors are all interchangable within the Cleveland family. Even 351C pistons will work in 400M. 400 pistons are all dished. The 351C pistons have the same compression height as the 400's. With the stock 2V heads, compression is down to about 8.5:1. By bushing the 400 rods to match the smaller 351C pin, you can use 351C flat-tops or even pop-ups to increase the compression. With flat-tops it's about 9.5:1. The best thing anyone can do to their 400, is to swap on a set of 4V cylinder heads. They are direct bolt-ons. Though I would recommend using a 351C intake and the adapter plates. Then there would be no sealing issues. Some of the 400 intakes don't have enough material to seal around the 4V ports. The larger ports really wake up 400's. I know, everybody say's that 4V heads kill all your low end torque. Most of those people never built an engine with these heads. They just "heard" or read in magazines they did. If they did, they probly tried to over compensate for the "low speed torque issues". That's the BIGGEST mistake anyone can make using these heads! The two things that people usually do is use a small (RV type) cam and run a smaller carb (351C or 400). Yes, the ports are large, but you have to make sure you can feed them what they need. Think about the 50+ cubic inches more they are feeding now. Know matter how they are built, a 750 is the smallest carb for any 4V headed motor. 4v intake ports (stock) peak flow at about .600" and around 300 CFM. So your lift needs to be as close to that as possible if not over. Use the heads to their potential, don't waste them. They really like a good bowl port job if you have time. If the cam you use is less, Harland Sharp sells a 1.8 ratio rocker for BB Chevy's. It'll work for any Cleveland and even 429-460's. As for the duration, That's up to you, but I wouldn't use anything less then 226-230 on the intake side. Split duration or single pattern cams? It's up to you, I've used both. Also, with my experience, these engines really like solid lifter cams. If your still worried about the "torque" problem, run the MPG port plates. They work really well. Especially if you have to run a small tube header or manifolds. If you can get away with it, try to use atleast a 1 7/8 " dia. header or larger. Don't use anything less than 1 3/4". Knowone makes headers for 400's with 4V heads, but we've had sucess adapting 351C headers to our motor. I haven't mentioned the 351M because I would only use them as cores (to swap a 400 crank into). Also, most 400's had C-6 or FMX Transmissions. Strong, yes, but heavy also. Most 351M's had C-4's. They are lighter and almost as strong if built right. Just don't use them in heavy cars or trucks. These are great motors. But just because they didn't have 4V carbs, weren't put into Mustang's, or they aren't motors "everyone else" is building doesn't mean the are no good peices of junk.

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