just wondering how to give my 351m a bit more *****. i would like to build a street/strip motor around 400hp. i understand that that the 351m are very low compresion ratio this costing it power. so i was think of building a 408 stroker with it. is there any easier way to get to this horse power range of should i do the 408 stroker kit.
As you probably know, the 351m is identical to the 400 except the pistons and crank. Thus, there are two ways to go.
First would be to find a 400 and just build it. Take your time, as your truck stays in service.
Second is to find a 400 crank for yours.
Everything else is going to change--pistons, cam, bearings of course, valve train. Heads are a question mark, as rebuilding stock heads can cost a good amount, making the move to aftermarket heads easier to stomach.
As "85" has suggested, definitely have a look at Tim Meyers site. He is currently the US (maybe even world wide)) guru on these engines. He can supply a whole range of pistons etc to do pretty much what you want. Not only does he produce a fully balanced 400 rotating assembly, and this may be exactly what you are after, he also does a 434 stroker kit. If I could make the homer simpson drool noise as a font,that would be what I would do. I would imagine that there would be a extra work done to make the best of that so realistically not just a drop in over the 400 crank assembly. really worth a look.
Any sort of reasonable rebuild with 9.5-1 comp should be around the 300+hp and 400+ft/lbs of torque which is a fair upgrade over standard.
Really up to you and how big the wallet is on the rest. Heads may need repair /replacement, what sort of cam, how many revs do you want, headers, intake manifolds, carbys etc., I am sure you have the picture already.
I rebuilt my 400 which is in a galaxie. it definitely goes a lot better than before, but the old C6, tall 2.7 diff and over 2 tons of weight means it doesnt break loose at will.
heads are the trick to power and a little compression$$$$$
if gonna be a dedicated drag racer type situation do the 434" better rods over stock for sure. 408" with nice heads and some compression 500 hrspwr. OEM 2v heads ported 425 pretty easy with compression and roller cam at sea level, but how much do you want to spend$$ just did a 408 ford for truck with cobrajet heads and they flow around 280+cfm but with intake flows less with dual plan intake ported, around 270cfm. many factors come into play when doing these projects. i have around 6500 to 7000 in this engine. carb to oil pan. carb was $900.00. so how much do you want to spend and what do you really need per application. i cut no corner on componets all new bolts (ARP everything) and many other upgrades. check my albums if curious.
I have a 408 in my 78 F150. It is nothing more than a 351M block bored to overhaul size, new pistons and a 400 crank.
I might point out that Horsepower is a calculated figure based on torque at a particular RPM. To have a high horsepower number usually requires an engine that has a torque peak at a high RPM. These engines do not lend themselves to high RPM work. What they ARE capable of giving you is TORQUE and LOTS OF IT! To get 400 rleiable horsepower from one of these engines will cost BUCKS.
For a modest investment OTOH, you can easily build LOTS of TORQUE.
Quite a bit more as if you did that you would really put higher comp pistons in as well. It is as easy as replacing any crank/rotating assembly and l am sure you realise you would need to bore / machine the block as necessary. How mechancally minded and how cashed up are you?