Is the 400 any better than the 351m? Does it share all the same problems? Poor oiling, cracking blocks, crappy crank as in the metal not being hard enough. I've been researching and I've been finding nothing but bad stuff about the 351m

 

Oiling is the same as all the Clevelands-so if you don't like that then stop now, otherwise not a biggy.
Some blocks crack but are well documented either up in the lifter gallery for certain years or if you bore the blocks too much-usually due to core shift.
Never heard of the soft cranks.
I will confess to knowing nothing much about 351M's specifically but their big issues are crap compression and decent rebuild pistons are non existent.
400's are the orphan of the 70's fords but a lot better than the 351m.

 

All it takes to improve the 351M is to put a 400 crank and pistons in it Really, I think that's probably why there's no pistons for a 351M; why bother with them when you can spend a little more money on getting a 400 crank and add 50 essentially free cubic inches? I've never heard of a 400 having a soft crank; as far as I've been able to tell from Tim Meyer's excellent work with these beasts, they're quite capable of going toe-to-toe with a 460 with a stock crank. There's nothing bad about a 400 except that it was born in the smog era and came saddled with all the restrictions that implies. Strip away all that crap, give it decent compression and some real airflow, and it's a respectable motor that will produce some respectable power.

 

^^^^ Agree completely.

 

I have also never heard of a "soft" or "crappy" crankshaft, my guess is that diagnosis was somebody's attempt at pointing the finger back at Ford.

 

mmmm No pistons available other than TMI. I used 351C flat tops and bushed the small end of the rod with 292 bushings and got 9.3:1 cr also ARP rod bolts and a grinding on the casting flash to smooth them out. If you want the FULL 351M to 400 info there are LOTS of members who have done everything from mild to wild. Not to HI-JACK but Hi CRSMIFFY How are ya !!! Popa J.

 

Andrew,

Don't worry! Yes the 400 is a better engine than the 351M. Yes it shares the same oiling system challenges but they are easily overcome. See Tim Meyer for performance help, he has done 400 builds making over 600HP, so you can do a lot if you want to. Never heard the "soft crank" thing myself, in fact some drag racers have been known to use the factory crank without issues.

The 351M is a purposefully smaller version of a purposefully de-tuned 400 - so yes it gets a bad rap. The 400 can be an excellent engine if built outside the confines of the late 1970's. Any reasonable rebuild of the 400 will net you over 300HP and excellent torque, so the real question is "What is you goal?"

 

Thanks for everyones replys. I'm just trying to see other people's opinions about these engines. I have a 351m but am going to swap it for a 351w but some people are saying I should get a 400.

 

Ford 400M Engine Rebuild - Classic Trucks Magazine

See them little do dads at the top of the cylinder walls? They are relief cuts for the valves. 351Ms and 400s have them. 351Ws don't. Why? Cause 351Ws don't have valves big enough to need them. Google Clevor and ask yourself what heads do you want.

 

Depends what you want to do. The aftermarket for the windsors is huge compared to the 400's but down here in aussie the 351clevo is one of our 70's god engines- massive respect.
Sucks you have the 351m as you would have to stump for a rotating assembly on top of any rebuild to really wake it some so that has to be considered.
As suggested check T Meyers website, he does not only a balanced rotating complete assembly for a 400 for not bad coin, he also does a 430 plus jobbie for a torque monster.

 

Andrew,

I don't think a 351W can compete with a properly built 400. To compete it would need aftermarket heads and those are available for the 400 (351C) as well. If you take the time to do a 400 right - it will be an excellent engine fo you.

Good luck on whatever you choose.

 

Ok so I know a guy I can get a rebuilt 400 that's never been ran. Still a short block. I can get it for $600. Is there a way to really tell if it's a 400 and what should I watch out for on it? Also how can I find out what year it is?

 

Look at the crankshaft casting information on Bubba's site (in the sticky) to determine the casting code you need to look for, I think it's "5M" or something real similar.

 

Tear it down, make sure it was done right. Rebuilt and never ran? Makes little sense. Might be, might be trouble. jmo, ymmv

 

He had it rebuilt for his bronco but ended up deciding on swapping in a 460. It will probably need tearing down anyway because it's been sitting awhile