I have decided to keep the original engine configuration which is the 351M engine. The only change I made was to convert it to a 400 cubic inch motor. The other option was to swap in a 460c.i. engine, which would include modification and fitment issues. There are a few companies that provide everthing to perform the swap but my main goal in my project is to keep it as original as possible. The Ford 400 has had rumors about its reliability and lack of perfomance floating around forever. This is exactly that....rumors and hearsay. Sure, any engine can have problems if not built properly, and there have been noted problems with these engines in the past. But if built properly, these engines have a perfomance capability that can rival a big block 460 dollar for dollar.
See Bubba's M-Block Workshop for more great info on these engines.

Click on the pictures for a larger version.

 

To convert a 351M to a 400 only requires a crankshaft and piston swap. That's it, everything else is interchangable. I got my crank from a local crankshaft shop for $120 already machined and ready to drop in. The most common piston used for the swap would be the flat top cast pistons from Badger, Ohio Piston or Dynagear. There are some folks out there that have used Keith Black hyperutectic pistons for the 351C. The only difference is the pin size. To use these, you must have bushings installed in your connecting rods. I opted for the cast flat tops for my build-up.

My build-up mimics an article that Hod Rod Magazine wrote a few years ago. They built a 400 for a Ranchero and had good results considering they used dished pistons, a two barrel carb, and all emissions gear intact. I used the exact cam they used, it's a custom grind from Comp Cams. Click here for cam specs. I also had the machine shop modify my heads to accept screw in studs, and Comp Cams Magnum roller rocker arms. Block was bored .030 over, decked and the heads were milled. I used Comp Cams lifters, pushrods, and valve springs. Edelbrock intake, and water pump. Melling high volume oil pump and an external oil line to help oil circulation to the rear of the engine. ARP bolts were used throughout the entire engine, and Fel-Pro gaskets as well. To top it all off, I used a Speed Demon 650 cfm carb.

So what did all of these goodies get me? Well according to DeskTop Dyno, the engine produces 400hp at 5500 rpm, and 441 lb/ft of torque at 4000 rpm. What I like the most is the torque curve which at 2000 rpm is 400 lb/ft and steadily rolls up to its peak at 4000 rpm. It starts to dip back down after that.

Click the image for the dyno specs

 

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