I have a stock 351m with c6 and its just not enough for me but i don't want to swap it. I have been reading some threads and I've seen there is a little aftermarket support for it. I would love to make it a 400 and if possible bore it over to whatever is safe. Anybody done anything like this to a 351m? If anybody knows of any websites to look at that would be great.

 

Why not see what you can wring out of the 351M (The "Mutt")? I mean, since it's stock, why not do the usual bolt-ons like exhaust, intake, and fuel system upgrades?

Some simple upgrades include an open-element air cleaner and a free flow filter is worth a few HP. It's amazing how restrictive the stock air cleaners are. Next, switch to synthetic lubricants... engine, tranny, and rear end. Don't forget to include some zinc oil additive.

Now the fun begins...First work on the exhaust. The rest of the upgrades will benefit from it. Take a look at Flowtech headers Summit PN BIG-32506FLT (2WD) or PN BIG-32520 (4WD) and 2.25-inch dual exhaust with mufflers of your choice. Best part is, the headers will also fit a 400 if you decide to go in that direction.

Second, a 4bbl intake and carb. Consider Edelbrock Performer PN 2171 (non-EGR) or PN 3771 (w/ EGR). Also consider Holley Action Plus, Jeg's PN 925-8010. Throw on a 600 cfm carb (Edelbrock 1405 or 1406 or a Holley 650 cfm (Jeg's PN 510-0-80453, smog legal!)) and call it good. Also consider a cam at this stage since ya got it all apart anyway. Crane's High Energy 268-degree cam is good from 1500-5500 RPM... it's at .494 lift so it should live with the stock valve train. Again, these parts can also be used on a 400.

Got enough to think about?

 

I dont know about putting full synthetic in it. It it has alot of miles one it i would go with castrol high mileage. It is part synthetic. I have just saw a few old engines have bearing problems after syn oil was put in it and ive also saw a few engines leak like crazy.. Just older engines with miles on them. You do what you want but just my opinion. Not starting an oil debate! .

 

TMeyer, Inc. Precision Automotive Machining

try the link above he probably know more than most machine shops about the 351 to 400
conversion. he also has kits to convert to a 400.

 

I agree, TMI is the guy to go to concerning the M-block engines, and he has his own variant of Keith Black pistons for the things. Give him a call, he's in Minnesota.

 

Theres a few thing that can be done without macine work.Aedelbrock alum intake the performer 400 is a good intake for a stock motor with a 650 edelbrock carb.Either flowtech or hooker headers.A good air cleaner and up grade the ignition.If this doesnt satisfy you the put u a decent cam in,the main problem with these motors is that they can breath.Now a set of 4bbl 400 heads will wake this thing up also.But on thing u need to do is put a tach in ur truck because these motors cant handle alot of high rpms,about 5000 rpm is all u want to push thisthing to.The oil cant return back to the crank case fast enough so they will starve for oil at high rpms

 

you can get a decent powerplant with the mods stated above. Somewhere in the low 200s for hp i believe.

 

Read me.

 

There's lots of that stuff in the Sticky in the 335 forum:

https://www.ford-trucks.com/forums/1...-projects.html

 

Another good recource:
M-Block 351M/400 Performance

 

Straight-up timing chain set, 4-barrel intake/carb, headers, good exhaust, and a complete tune & you should be happy if the rest of the motor is in good shape.