rebuilding and modifying a 351M/400 Vs. putting in a 460 [Archive] - FSB Forums

: rebuilding and modifying a 351M/400 Vs. putting in a 460


rockon23
06-22-2007, 09:11 AM
my truck has a 351M/400, but latly its been giving me troubles. i was woundering if i should rebuild the 351M and modify it, of buy a 460. im thinking if i modify the 351M, i might be able to give myself more power than the 460. but the 460 would take less time. what shall i do?

chebbykiller
06-22-2007, 09:26 AM
If youre willing to spend the cash to modify the M, might as well go with the 460. Get one cheap at the junkyard or craigslist, and build it up just a little, youll get plenty out of it.

ghglenn
06-22-2007, 09:48 AM
You need to go to this link [URL="www.projectbronco.com/index"] they have some tech articles with good info on the pros and cons of doing each option...IMHO the swap is the way to go and I am gathering parts for mine.

Good Luck,

G.T.

chero65
06-22-2007, 10:18 AM
if you just did a stock rebuild with something like an edelbrock performer package on the 460, you would have plenty of power. personally, i like the 460 over the modifieds. some people like the modifieds, they are lighter and can make just as much power with the right machine work and parts. so, if power is what you are looking for, a stock 460 should give you more durability and driveability than a bored out, cammed up modified. depends on what you want, a mud or rock truck, or a driver that you can play with on the weekends.

rockon23
06-22-2007, 03:52 PM
what would give me the most power at resonable price?
ive always wanted a 460. but im tight in the budget

im willing to pay around $750

InfoFord
06-22-2007, 04:39 PM
the 460 is the best bang for the buck for power

750 won't even hardly buy a stock assembly line rebuilt 400 let alone any mods done to it to make power

chero65
06-22-2007, 06:25 PM
what would give me the most power at resonable price?
ive always wanted a 460. but im tight in the budget

im willing to pay around $750

for $750, look for a good running used motor at a junkyard, or an old ford, lincoln that has one in it that someone is selling for cheap. picked up my block at the junkyard for $500. Machine work-$2100. Parts-$2400. It isnt cheap, depends on what you want. If you dont do a rebuild now, probably will have to down the road.

79F150
06-22-2007, 09:01 PM
Machine work-$2100.


Who in the hell did you machine work???? I got my M block bored, dipped, sonic checked for cracks, cam bearings and freeze plugs for $380.00

Bought a reaman 400 crank for $180.

chero65
06-22-2007, 09:21 PM
Who in the hell did you machine work???? I got my M block bored, dipped, sonic checked for cracks, cam bearings and freeze plugs for $380.00

Bought a reaman 400 crank for $180.


i included the parts the machine shop got. motor was sitting outside, ruined the entire valve train. new everything for the heads and valvetrain (lifters, pushrods, valve springs, seats, valves, etc), hot tank, rods, cam bearings, cam, freeze plugs, line bored, bored .030, machined block and heads, turned crank, pistons and rings, timing gear, oil pump, all bearings, assembled short block, etc, etc. the rebuild kit alone was $700-$800. ;)

not saying you cant get it done cheap, depends on what you have done.

JRBogie
06-23-2007, 01:15 AM
I have rebuilt m-motors before. they are not that expensive. I had the bore, clean, mag, and sonic done for under 300 and i got a lunati cam from summit for 180 and a full rotating assy for 300 so that is your 750 right there as long as you dont have any cracks or breaks or any of that you could actually rebuild for a little cheaper because you dont need a full rotating assy

JRBogie
06-23-2007, 01:16 AM
oh, i put a performer intake and holly carb on that i got for free too

v8only
06-23-2007, 10:42 PM
what do you use it for??

personally I have my mustang which I use as the car to modify the shit out of for performance. My bronco, I've decided I don't care. Beyond good exhaust and a 4 bbl intake upgrade to my 400, I'll stop there, and that should get me well into the 200's for HP on the 400, which is plenty for rock crawling.

couple of things to keep in mind...because of the known oiling issues with the modified motors, maybe it's just me, but I wouldn't trust a used motor too much. Of course, if you got a good deal on one, you could always swing it updside down and put new rods and mains and oil pump onto the used motor, and you'd be good to go for cheap.

as far as the 460, I'd LOVE to have one, but I have to remain smog legal, so for me, that means finding a 78/79 block, as those are the ONLY year 460's that will work for mine and be smog legal.

for that reason, I searched around, and found a killer deal on a complete reman 400 motor for $700, never ran. Old man bought it a few years ago and never used it.

lots to think about. While the conversion parts for the 460 swap are cheap, anything can add up, so if You have to stick to your budget, consider you can drop $750 into your current block instead of picking up a 460 block and getting the conversion stuff on top of that.

78moneypit
06-24-2007, 01:03 AM
I hate to tell you v8only but you could have put a 460 from 78 to 97 in your 78 and still be smog legal in Calif.

Rockon23 check your state smog laws for engine swaps.

Putting the 460 in my 78 was the best thing I've ever done to it.

bronco_kid78
06-24-2007, 02:20 AM
Wow perfect timing. I just made this decision about a week ago. I can spend about 5k in parts and make a 460 put out over 525hp and if you go with the 400 expect maybe 8k. I don't know but the all-round potential of a 460 is far greater than a 400. I am a huge advocate of the 400 and absolutly love my motor. But I want more and the 460 offers exactly what I'm looking for. The possibilities are endless with the 460. And yes you can do a lot with the 400, but through my research I have found the output per dollar is not nearly as high in the 400 than it is in the 460. My $.02

OX1
06-24-2007, 08:55 AM
The only reason I would keep the 400 is if you have done all the bolt on mods already. If you already have a 4 bbl intake, smaller 4 bbl carb, headers and rebuilt/new items like fuel pump, water pump, newer stockish or 4 core radiator (but not the big block specific radiator). Add the 460 specific swap items that will be needed like motor mounts and most likely accesory brackets (unless you got lucky and it's van motor).

Add all that stuff adds up to a big chunk of change that could be spent on a 400 build vs just getting the 460 in and equivilant mods to it you had on the 400.

460 wins for power hands down, even just mildy modified.

rockon23
06-24-2007, 09:44 PM
alright, i guess i will do the 460 swap. plus ive always liked the 460

v8only
06-24-2007, 10:02 PM
I hate to tell you v8only but you could have put a 460 from 78 to 97 in your 78 and still be smog legal in Calif.

Rockon23 check your state smog laws for engine swaps.

Putting the 460 in my 78 was the best thing I've ever done to it.


not true. In order to be smog legal in california the engine has to come from a vehicle in the same weight class as my own. the only vehicles to come with a 460 in my weight class are the 78/79 cars and trucks.

I spoke with a referree personally. He said they'd be checking the block for date stampings.

so My question is, if you make a statement like this, do the 460 blocks have NO date stampings on them??? If I got a 460 block out of a later Ford, are there no stampings on the block to say that it's an 84 block or whatever???

If that's the case, finding a block will be a ton cheaper and easier for me, as I won't have to search for a two year only block.

ruger1022
06-24-2007, 10:27 PM
The only reason I would keep the 400 is if you have done all the bolt on mods already. If you already have a 4 bbl intake, smaller 4 bbl carb, headers and rebuilt/new items like fuel pump, water pump, newer stockish or 4 core radiator (but not the big block specific radiator). Add the 460 specific swap items that will be needed like motor mounts and most likely accesory brackets (unless you got lucky and it's van motor).

Add all that stuff adds up to a big chunk of change that could be spent on a 400 build vs just getting the 460 in and equivilant mods to it you had on the 400.

460 wins for power hands down, even just mildy modified.

What the deal with the van motor? I know of one in DFW out of a van with a blown tranny, carburated, for $400...Apache Motors in Mansfield. Wished my other half that controls the budget would allow for it.

78moneypit
06-25-2007, 12:01 AM
not true. In order to be smog legal in california the engine has to come from a vehicle in the same weight class as my own. the only vehicles to come with a 460 in my weight class are the 78/79 cars and trucks.

I spoke with a referree personally. He said they'd be checking the block for date stampings.

so My question is, if you make a statement like this, do the 460 blocks have NO date stampings on them??? If I got a 460 block out of a later Ford, are there no stampings on the block to say that it's an 84 block or whatever???

If that's the case, finding a block will be a ton cheaper and easier for me, as I won't have to search for a two year only block.

It gos by GVW in Calif a 78 bronco is 6100 GVW 6000 GVW is considered heavy duty so you can put a 78 through 97 460 with all the smog that came with that engine in a 78. That referee doesnt now what he talking about. Look at my 78 i went to a Calif referee he had to call big boss Sacramento the big boss asked whats the 78 GVW. He tells the boss its 6100 i hear the boss tell referee to pas it that how it went for me..:thumbup

The referee put a sticker under my hood for smog shops to smog this truck as a 97 f250.

v8only
06-25-2007, 01:33 AM
It gos by GVW in Calif a 78 bronco is 6100 GVW 6000 GVW is considered heavy duty so you can put a 78 through 97 460 with all the smog that came with that engine in a 78. That referee doesnt now what he talking about. Look at my 78 i went to a Calif referee he had to call big boss Sacramento the big boss asked whats the 78 GVW. He tells the boss its 6100 i hear the boss tell referee to pas it that how it went for me..:thumbup

The referee put a sticker under my hood for smog shops to smog this truck as a 97 f250.


I'm going to pm you so as to not completely hijack the thread...