I have a 1979 f-150 on 40" boggers with the stock 351M engine and C6 tranny. I'm looking at doing an engine swap to try and get around 400hp N/A. Just wondering what engines I should look into for doing something like this. A "bolt on" engine is what i'm looking for to keep the $$ down so no custom brackets will be needed. Needing a little more power to push through the mud!!!

 

Welcome to FTE.

You have 2 practical options. You can rebuild your 351m as a stout 400 very easily (all the 351m is, is a destroked 400). Or you can swap in a 460. The bellhousing bolt patterns are the same so they swap pretty easily. There are lots of threads here about the 460 swap. A search on this forum may inform you more about whether or not you want to swap.

 

On a mud truck, I'd say go with the 460. With 40" tires, you don't want horsepower, (it sounds ridiculous, but hear me out) You want TORQUE. Torque is what gets the tires moving. A 460 has loads of it in stock form. If you have more horsepower than torque (a typical gas street engine) you won't do near as well in the mud.

My advice is to get with an engine builder and work on some numbers. Buy a used 460 and build it while you're still driving your truck. Then you can do the swap with minimal down time.

 

Ok I'll start looking into the 460's, I think that would be a better bet than building up the 351. That way I can get more power out of it later if I need to rather than maxing out the M.

How much would a swap like this cost though? and would I be able to get any kind of money for the 351...its pretty old

 

I go/vote for the 460. Can go 550+ cubes with a stock block. Cores are cheap and available.

 

Since you said you want to keep the cost down, I think you should take a look at making a 400 out of your 351m. The 400 has a longer stroke than any other engine Ford ever made (yup, even the 460), and stroke can translate into torque potential. You already have the block, and everything else needed, you just need the internals for the engine.

The shopping list I'd attend to first would be a 400 crank (stroker crank from TMeyer would be even better, but you'd have to upgrade to 4 bolt mains to deal with the increase in torque), a set of flat top pistons (again, from TMeyer), a straight up timing set, and good carb, intake and headers. If money allowed, I'd go with either a set of Australian 302 heads, or a good set of aluminum heads from CHI. Even without the heads, 400hp out of a 400 is easy to achieve, and you'll have buttloads of low end torque at the low end of the rpm band.

You don't have to take my word for anything, but I would suggest that you give Tim Meyer a call at Tmeyer, Inc. He's the guy to talk to about the 335 class engine (351C, 351M, and 400), and would be able to tell you pretty definitively what you can do with what you already have. Yes, I'm biased toward the 400, but it's because it can be made into a firebreather, and it's the path less traveled.... while the 460 has great potential too, and even moreso for just sheer displacement, it's stock numbers aren't anything to write home about either from those that were built during the same time that the 400 was produced. Either way, it's your call, but I figured you should have complete information before making a decision. Personally, I love both engines, the 400 and the 460...but to keep cost down in this particular case, I'd say build the 351M into a beasty 400, instead of investing limited funds into a different block all together, and then building from there.

Again, just my $0.02

 

Still can easily outdo 335 series class in torque per dollar with a 460 IMO. 429-460.com

 

if you have a 351m a 400 is a great upgrade. summit sells some pretty cheap cams, you can call tim meyer about some pistons, intakes aren't too pricey, headers aren't too bad either, and after all that you could be pushing out 350hp and 400+ftlbs of torque. plus, your torque will peak at around 2000-2200rpm (which will definitely go great with those 40's)

if you're dead set on a motor swap, then i would definitely go for a 460. gobs of torque and horsepower for cheap. you can hit up L&L about all the swap parts (mounts, headers, etc.). a 460 will put a little more weight up front but nothing too much. performance parts are everywhere because the 460 and 429 utilize the same parts (minus crank and pistons).

either way, it isn't very hard to do either one for cheap. keep in mind that a 400 will peak in torque at a lower rpm than a 460 will. not trying to scare you away from the 460, just giving you the heads up on what to expect.

 

Much easier,cheaper and more reliable to get the power from a 429/460 than a 351M or 400.

The aftermarket for the 385 series is much bigger than it is for the 335motors,which gives you more options,and brings the price down.

 

I think I would rather have a 460, because of the many performance options but I don't know if it would be worth it for the extra money. I would need to buy a 460, do the mods, then the swap, whereas the 351 is just a build up. I'm not looking for massive power, just a good amount of torque to keep from bogging down in deep mud and getting stuck! Not moving without the tires turning

 

I have done both,change a 351m to a 400,not worth it and use the 460. Go 460 and you can leave it stock and have plenty of H P and torque.

 

I would think the 400 would be the way to go. From past experience on this forum it seems like at around 425hp and up the 460 starts to become the better deal as far as cost goes. There are some good threads about 400 vs 460, they get pretty opinionated but if you can weed through the bias you can find what's best for you.

And just for the record, you are in no way "maxing" out the 335 series. John Kaase won the Engine Masters Challenge in 09' with a 656hp/618ftlb!! 335 series engine. It's big money for big power like that (read above statement, if you plan on more than 425hp, go with 460, or be prepared to light your wallet on fire) but just so you know it's capable.

A stock ANYTHING from 73-79 is nothing to write home about. I think the post 72' stock 460 was rated @ 225hp and 375ft/lbs. So you're going to have to build regardless.

 

400+ hp would be plenty for my purposes, so I think I will go with building up the 351.

Just out of curiosity does anyone have experience with 351M/400 using forced induction? If I did want more power out of it later on would that be a possibility or would it be pushing the limits of what the engine could handle?

 

I think you may be pushing the limits of a 2blt block with turbo, but if you had a 4blt you'd be ok, but you will have to change pistons. If you build a solid 400, you are going to have 9.3:1 CR pistons. That's too much CR to run boost. So I would say if you plan on boost, build it that way from the start. I think a turboed old gasser is pretty original and very cool! I've seen just a few done. You'll have to custom make your exh/turbo plumbing though. Nobody makes a kit for these things.

Don't bother with supercharging IMO.

 

A power adder on a 351M is equivalent to lighting a stick of dynamite so you can see at night.It will be ok for a very short time...then BOOM!

Without spending a BUNCH of money,a legit 400+ hp out of that M is just a dream.To each his own,but from experience,the 3-400 bucks you spend on an old 460 to start the build is peanuts compared to the extra $$$ you will be throwing at that 351 to make a fraction of the power and reliability you would with the 460.If you are on on budget an M will make short work of eating it up.

Find someone who has built a dynoed 351/400 w/400 hp,and someone whos built a dynoed 429/460 w/400hp,and compare their receipts.

Ive had several(50+)70s Fords with both motors,so Ive been there.

The 351M has its place...but,powering a big horsepower truck is not one of them.