i recently picked up a 351 m that is all done up. its 30 over,has edelbrock intake and carb,radical cam{not sure of lift},racing oil pan and super comp headers with c6 and 12 k on rebuild. its currently in an 85 f100. i have donor 390 but needs work. my question is how hard is it to install this beast in my 66 f 100. dont want to chop it up . i have original 352 but needs more work than doner 390 . i picked modified up for nothing and is totally worthy and still in 85.was going to find a buyer and rebuild 390.has anyone else done this before,it looks to be as wide as 390 but is different all in itself......

 

I think the engine perches for the 351M/400 are different than what you have but starting in 1977 the engine was used in F-series pickups and the front section of the frames are the same from 1965 to 1979 so you should have no problem locating a 77-79 in a salvage yard to obtain the correct engine perches. Then the engine will drop right in.

It is just my opinion but a 351M/400 are good for one thing, and that is on the end of a boat anchor. I would not use it, and would go with the 390 myself but it is your choice.

Jeff

 

thanks for the input. i have a really good 390 that needs a minor rebuild using original pistons. there is no ridge and pistons are tight. plastic timing gear still good!crank is mint. the 351m is nice and could drop the whole thing in cheaply. dont know much about this beast.are there certain problems,are they all alone? the previous owner dropped about 4 grand in motor.

 

The engine came around when engines started getting emssions crap. They have low compression, EGR and if I remember correctly they tend to crack cylinder heads. There is limited performance parts available and are more expensive to work on. I am sure there are more things but those are off the top of my head, other members can chime in with there thoughts.

The good thing about that combo yuo are looking at is the C6 transmission as they are bulletproof. The 351M/400 use the same bellhousing pattern as a 460 so down the road you could drop a 429/460 and use the same transmission.

Jeff

 

thanks for info, c6 trani is rebuilt and drives good. would i be able to use behind 390? is this motor in the 429 460 family?

 

No, the 390 is in the "FE" engine family same as 352/360/406/410/427/428, if you look at the bellhousing it will look round. The 351M/400 have the same pattern as the 429/460. The internals of the C6 would be the same but the case is what is different.

390 engines are not cheap to work on either, but there are a lot of performance parts available and in stock form a 390 is a very good running engine and can be built to perform even better with a few goodies.

What do you attend to do with your pickup? If you plan to restore and keep everything in stock form I would go 390. The 390 was not offered until 1968 in a F-series pickup, but from the outside looks the same as a 352 which was offered in your 66. If you just want to refresh your truck with better running engine drop the 351M in, and as I said earlier if you desire more performance than what the 351M can provide remove it and drop a 460 in. Either way the choice is yours.

Jeff

 

The 360/390 is a FE, 429/460 is in the 385 series engine family. Completly different bell housing.
Also, Ive only been on the ford train for about a year or so, but this is the first time that I've heard about a 351M/400 having the same bolt pattern as the 429/460. 351M/400 are considered small blocks, aren't they ?
I'm not sayin' your wrong Jeff, I've just never seen/read that before. Darwin

 

Lots of details here, and they all get confusing.
351M-400 swap: Your 352 perches will suffice for the 351M, but you may need to move them forward. If you go with power steering, you'll need to get the driver's side perch from a '70 - '76 truck to clear the PS box.
You will also need to use the 351M transmission, as the FE Family bellhousing is shaped differently.
Note: It is the 351M (for modified) but the 400 designation has no M. The 351C, 351M and 400 are the members of the 335 series. However, I am told they have the same bellhousing shape as a 370/429/460 which are the 385 series members - but I cannot say that of my own knowledge. Check out the 335 and 385 forums here at FTE, they will probably have better information. If the 335 and 385 bellhousings are the same you can move from a 351M to a 429/460 easily enough, at least as far as the transmission goes. (I have heard there is a rare 351M with the Windsor bellhousing pattern - but I do not know anything more.)
The FE family, which includes the 330, 352, 360, 390, 406, 410, 427 and 428s all have round bell housings.
Because the C-6 has an integral casting for the bell housing, you must use the correct one for the engine family.
If you swap in the 351M, you will have to make alterations in the throttle cable, the shift linkage inside the transmission (at least, if you want to use LOW gear), and the exhaust.
By the way, notice the word "family." The terms "small block" and "large block" are Chevy - GM terms. It harks back to the days when you could get a large block sized or a small block sized engine, but both were only 350 CI. They were different engines.
The threshold today is often put at 400 CI - which doesn't work for the FE Family. As already noted, a 352 and a 428 can look identical on the outside, but they are vastly different inside. So you can see that the term won't fit.
As to swaps, I think Jeff is on the money with the advice for the 351M vs 390.
As for power, I have a 460 - and yep, love it.
The only drawback to using a 460 is you must use the factory 460 perches, which are hard to find, to get it all to line up right.
Other than that, the 460 offers a lot of options. I even used a '90s 460 serpentine system on my '66, and it looks as works great.
Best of luck!

 

Hey guys, Shouldn't a 351 in a 85 be a W instead of a M?


John

 

Good catch, John!

 

Is it really a 1985? 351M's were still used in 1980 and maybe 81 as I do not recall the last year it was used in F-series pickups. The engine could have been transplanted by a previous owner just as this post is looking to transplant into a 1966.

Look where the water outlet is on the engine. If the upper radiator house comes out of the block it is a 351M, if it comes out of the intake manifold it would be a 351W. There are other things to look for to positively ID the engine but that would be an easy place to start.

Jeff

 

it looks like theres no front cover and tstat is in block. it has nice headers on it but dont know if my 73 ps box will fit with pipes. i have the motor mounts from cs where 390 came from . i will sacrifice ps for headers.85 had swap donebefore and have 351 c or w in bed of truck.i have pictures but havent figured out how to showem.thanks everyone for all much needed info,jim..

 

Check out this link, especially the pictures at the bottom. It will show you the 335 engine thermostat's position in the block.
Ford 335 engine - Wikipedia, the free encyclopedia

 

To install a 351M/400 block in a 65 to 79 truck you need 302/351M/400 mounts...and the correct Big block (351M/400/429/460) bell pattern for the bell housing or transmission.The 351C will mount on the 302/351m/400 mounts and use a small block (302/351W) bell pattern

The FE/I6 mounts are 1 inch too high...Common mistake when dropping in a small block.

85 if it is stock would have been a 351 4V Windsor HO. in 86 they switched to EFI. 302 for 85 were EFI. last year for boat anchors is 82/83 model year.

Garbz

 

Dave, 86 351 4V Windsor HO is still carbed, while the 302 went FI, but not EFI.


John