I am street rodding a '51 F100 and have recently purchased a 351M. I am interested in bringing it up to the 400. From what i read all I need is the Crank and Pistons from a 400, is this true, and are there other modifications anyone would suggest. Hoping to get around 400 HP. As always this is on a family budget so savings are important.

I also have a C4 off of a 302, so I would need the larger bell housing. I'm thinking of moving to the C6. Any pros/cons on this thought.

Any help would be appreciated.

Ray

 

You can easily turn a 351M into a 400. All you need to do is get a 400 crank kit(comes with main and rod bearings) and 400 pistons. You can use 351 Cleveland pistons if you have the rod ends bushed. I put KB 351C pistons in mine for 9.5:1 cr.

For the most part, anything that works for hopping up a Cleveland will work for a 400.

You'll definitely need to go with a C6 if you want a strong AT. Get a 400/C6 flexplate (flywheel) and you can use most any 351M/400, 429/460 C6. The 460 C6 will be the easiest to find.

Where are you located?

 

What's in your budget?

 

i am doing the same thingraycer944 with my '79 f150. turned the 351m into a 408. it has also been bored .040 over

 

Josh79 - a 400 bored .40 over would be 410 - your thinking of .30 over - remember when doing calculations, the actual displacement is around 402.

As for hopping it up - Im not sure if shorties or block-hugger headers exhist for this engine, and what you plan on dropping it in there are no aftermarket headers available for, so running a good custom exhaust is a must.

As for power, Your best bet would be to overbore the engine .020 or .030, do NOT exceed a 40 overbore I warn, they do make 60s, but 40 is the maximum you safely want to bore this engine. When buying pistons, For maximum compression, get a good set of Flattops, or cleveland pistons.

Next would be a good cam, and a double roller timing chain - Depending on what you want, lots of low end grunt, or horsepower at high rpms (which, this engine is primarily used for low end grunt) you have several choices on cams from such companies of Comp, Crane, or Lunati. Be sure to buy the kit, its pricey, but it will come with the necessary valve springs, new lifters, valve seals; just about all you need.

Next, for weight reduction and performance increase, lose the stock iron intake and get a 4 barrel aluminum one. Edelbrock and Holley make these, a few other companies as well, not sure which though.
Just be sure to do lots of research. The 400 can be one of the best engines to build - if you know how to do it right.

Good luck, have fun!

-Daniel

 

They don't make aftermarket headers for the 400?

Oh, no headers made for a 400 in a 1951 truck...


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Sanderson makes block-hugger headers for the Cleveland motors - I don't see why they won't work on the M motors. They have collectors that dump in a couple of different locations, I'm betting you could find something that clears

 

Well, block headers for a Cleveland might very well work since they use the same heads as the 351m/400. Im not sure how the frame to a truck of that year is spaced, so I cant make any for sure statements.

If you want to get down to it, as long as you just run plain ol' steel headers and not the Cerama-coated ones, there is nothing stopping any header from being 'made' to fit. Just be careful.

-Daniel

 

My friend runs Shoenfeld headers on his 75 F-100 with a 400M.

 

there are some 351m/400 headers made by hooker competition headers

 

Thanks for all the feed back. This help to reinforce much of what I've seen around on the sites.

I am deffinately going with he 400 crank kit. I'm still trying to decide on the pistons. I've heard there was an original TRW set of pistons that came in the 400, is this true, and can they still be found?

And I will be going with the C6 as well.

A Holley 650 I believe will do it. And a Comp Cam #268.

 

even a 600cfm would be a little better. Edelbrock makes one that is great for the 400 BB . model # 1406. try it with an edelbrock performer intake and cam. all made for low end TQ and Mid range HP ( idle to 5500 RPMs) and flat top pistons would be better, boost your compression from 8:1 to 9.5:1. Alot better like from 175HP to around 265Hp. Just my two cents.

 

Get a 750. Works better.