On the 351M vs 400 question. 50 more cubic inches helps torque for trailer towing and some more power. There are just a lot more performance oriented parts available for the 400 including and especially higher compression pistons.

351 and 400 share the same bore size... whether your engine needs bored or not depends mostly on current condition of the bores. It may need a small overbore in any case to get it trued up.

 

Don’t waste any money on a 351M/400 go with a 460 or a 429 you’ll be much happier all the way around

 

ok thanks for your help guys i think i am going to stay with the 351 and not go to a 460 because i have 0 fab skills. and the efi would be nice because it gets real cold in the winter and i dont want to have to warm the truck up for a long time befor i can drive it. i think im going to talk to a shop some time this week and see if he would be interested up grading it to a 400 with more upgrades.

 

I have been running a 400 in my 72 Ranchero for years. What a lot of people don't know, is the piston pin height is the same as the 351 Cleveland. What's different is the pin diameter. Have the small end of the 400 rod bushed to the 351 pin diameter and you can run 351 Cleveland forged pistons in it. They come in all different compression ratios so getting your desirable compression is easy. Also, try to avoid the detonation prone open chamber heads. The Aussie 2bbl heads are decent but look at what the cost to machine vs new aluminum heads are. The difference may not be that much. A 400 has a lot of potential and is lighter than a 460.

 

And the next guy will say forget the 460 and simply drop in a Cummins.
Then Hio Silver will drop the ace and say buy a Ferrari instead...

We have all heard where this is going, countless times...

 

I don't know about what you just contributed, but I was merely showing him how to improve on what he already has for less money.

 

Then I must not have been referring to your post then, hmmm.

 

The path of least resistance is to rebuild what you have for performance.

Once you have the engine pulled you need to determine whether or not it can even be rebuilt.

If yes. Build it up
If no...well consider finding a different 351m to build or a swap to 390 or 460 if you need to tow a lot. Or a 351w or 302 if you just need to haul loads in the bed.

 

the engine has been out of the truck for a while and it is worth rebuilding imo. i'm going to talk to a guy that rebuilds engines and see what he can do for me. and i think i am going to get either a fitech unit or a holley terminator. thanks for the help guys

 

I guess what I meant was you need to tear it down and inspect it to see if it can be rebuilt. For example the block or heads could be cracked in which case you may decide to go another route with your build.

 

Small block chevy gen 5. more power and double the mileage of a 460. Bolts in to these fords, factory 11:1 compression and 6 speed automatic.

Attachment 286821


LOL sorry couldn't resist.

 

Stick with the 351M. Headers good exhaust and EFI will wake it up nicely!

 

the motor ran fine before disassembly just want to have it gone through/ rebuilt. i think ill stick with a ford motor but thanks jacobj. does any body have a figure on horsepower for a stock 351 and a stock 400?

 

Easiest thing to do is rebuild 351, but no reason NOT to go 400. Likely be replacing pistons anyway if overbore, so only additional needed is 400 crank. More noticeable torque than 351 due to 4" stroke (vs 351's 3.5").
I have done 2 460 swaps into 79 4wd's. Although not difficult, more involved than 351M/400. Being 4wd, can't do it with all factory parts. 2wd you could.
A 400 with a 4bbl intake/carb, cam advanced 4 deg using double roller set, runs just as well as a 90's era EFI 460 (stock) converted to carb. That being said, there is probably way more potential to build the 460 for performance if so desired, not what I was after.

 

As OEM for '78, based on the list in the following link, the numbers are:
351M: 132/137 HP, 242/257 Torque. (MT/AT)
400: 149 HP, 300 Torque.

Engine_Specifications

A 400 with 9.5+ compression, a better cam, intake and headers would easily turn out 350 to 400 torque, and 300+ HP without much stress.

I will look for some links for you later tomorrow. I can't find the right piston link for what I think are "KB2344" pistons.