I have some questions about my 351m motor. From my understanding it is a very easy process to convert to a 400. Is it as simple as it sounds? And would it be worth the extra power with what I lose in gas. Power is a big concern of mine, but getting at least 10 mpg is also a factor. Any help is appreciated

 

You would be better off just swapping an a stock 460. The bellhousing is the same so a new transmission is not needed. Just get some mounts and bolt her in.

 

How much is that gonna set me back? And what kind of mileage can I expect?

 

Also where would be my best bet to find one?

 

Depends on what transmission you have, if it's 2 or 4wd, and how much you're wanting to spend



Jameson

 

Automatic transmission, 4wd, and I'd like to spend the minimal amount on this upgrade

 

If you are worried about mileage do not do a 460 swap. They are thirsty beasts. Minimal is not a word that goes with a dent 4x4 460 swap. Ford never put a 460 in a 4x4 dent so right there to start you have buy a kit or custom fab. If you want to go with manifolds the right side is truck specific. You will also want to swap out the timing set for a '68-'71 timing set. It brings the cam back to 0 increasing power. I have read about somebody who got 14 out if a 2WD 460 but the majority I read is 8-10 (2WD). No idea what I get. I built my truck for fun. Mileage is not even a thought. Going fast is though!

 

What about swapping in a stock 400 then? What can I expect there and where is my best bet finding one? I have heard there's no real change when it comes to gas mileage between the 351m and the 400

 

Swapping a 400 is a piece of cake, they are basically the exact same engine on the outside. It shouldn't be all that hard to find one, they were in a lot of trucks and cars for 10 or so years. Like said above you can swap to a 400 crank and make your 351 a 400, but you would need new pistons also. So if you were doing a complete rebuild it wouldn't be a bad way to go. the 335(351m/400) series engine is lighter than the 385(429,460) but doesn't have the power potential of the bigger engines. Neither is going to get that good of mileage, but 10 is doable with both.

I would watch craigslist and check your local pull-a-part yards.

 

Thank you ill be sure to do that. and if I do upgrade to a 400 should I also upgrade to a bigger carb? I am currently using a 2 bbl

 

I think you'll be fine with a 2bbl if the engine is stock. Besides, if you wanted to go to a 4bbl you would have to get an aftermarket intake

 

So just getting a rebuilt 400 is probably going to be my best bet, thanks everybody!

 

Depends on what you want out of it really? I just put an aftermarket intake and 4bbl on mine, 4bbls aren't really designed for mileage but if you keep your foot out of it probably would be ok. One of the biggest improvements from my understanding is replacing the timing chain. From the factory the cam is retarded 4 degrees, changing it to straight up I hear makes a big difference. I don't know yet I haven't had a chance to put mine on yet, but will soon.

If you want mileage the timing chain, headers, and a cam designed for improved mileage would probably be the way to go. Wouldn't be all that much in cost, watch for used parts on cl also.

 

Where do you get your stuff from? This is my first truck, I don't get my license for 7 months still so taking time to get this truck where I want it is an option. I have all the time in the world, just not all that much cash. I have a little over a grand to play around with

 

What should I look foe in the new timing chain?