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What are, if any are the differnces mechanically between a '78 and '81? I currently have an '81 Bronco with a C6 and a 460 in it. I found a '78 with a 351M in it and would like to swap at least the engines and possibly the trans. Is it possible? Thanks for all the help.
 

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As far as I know, the engines and transmissions should be a direct swap.
 

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It should be a direct swap, I think even the mounts would work, but since you have mounts for both, no issue. You may have to change the transmission cross member, but again, you've already got it so it shouldn't be an issue. Can't say as I blame you for wanting to swap, that 460 is thirsty!
 

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Age. Fac ut gaudeam
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The 460 is better, just rebuild it.

Or are you swapping over to the 79?
 

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The 351 is in better condition. The 460 needs a little work have not decided to rebuild it or sell it. Thoughts pro cons?
 

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Age. Fac ut gaudeam
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Well, both will get shoddy gas mileage, if you rebuild the 460, try and use light performance parts and buy a fuel injection kit from Summit, help your gas mileage out, I believe people here also swap the fan out of like a Ford Taurus for a fair EM-PE-GE increase. Upgrading to a 3G alternator...

Cons are it's a heavy engine, and won't ever get awesome gas mileage, but is probably about the same as the 351M
 

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351M sucks as far as I am concerned. As for mileage from it, I once did a comparison with the 351m. At 60mph and being nice I got 10.1mpg, at 90mph I got 8.8mpg . Both on the highway on one trip. Needless to say after two tanks at 10mpg, I swtiched over to go fast and hope not to get caught. That was with 31 x 10.5's . I think, in my mind, that I would have gotten better mileage with my 35's. But I had taken them off for the trip to save gas.
 

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351M sucks as far as I am concerned. As for mileage from it, I once did a comparison with the 351m. At 60mph and being nice I got 10.1mpg, at 90mph I got 8.8mpg . Both on the highway on one trip. Needless to say after two tanks at 10mpg, I swtiched over to go fast and hope not to get caught. That was with 31 x 10.5's . I think, in my mind, that I would have gotten better mileage with my 35's. But I had taken them off for the trip to save gas.
Sounds about right to me. You won't do any better with the 460. My '79 averages between 7.5-10 mpg. THen again, I didn't buy my truck for the fantastic gas milage. It would be nice to get more out of it, but probably won't happen.
 

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Ok. Let me tell you what I know.


351m can be good engines if you get the smog crap out and get the straight up timing. Plus the 351m is also a lighter engine unlike the 460.


http://www.projectbronco.com/Technical_Articles/351m400_performance_build_up.htm
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460 though can be made into a monster and will gain alot of hp and torque and alot of parts are usually available for the 460.


My 79 F150 4x4 had a 351m but I wanted to make a monster so I put a 460 in.



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The old Fords usually had Positive Traction to in the rear end making it good for pulling..and plus the older stuff was built better and quite simple to fix.

The old Fords transfer cases are excellent.


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Pros for the 351M
-Light weight
-With minor modification can be an ok engine
-Can be made into a 400M with 400M (6.6) crank and pistons

Cons of the 351M
-Gas/MPG
-Stock performance...sucks

Pros for the 460
-Torque monster/Hp monster
-Can be bored alot and made into a high cubic inch motor
-Parts are usually available for them

Cons for the 460
-Heavy
-Gas/MPG


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Engine swaps from 351m to the 460
-The 351m towers can be used to put the 460 in
-The 460 will need new motor mounts
-You might have to get different power steering pump brackets and alternator brackets
-If you have a F150, you may can squeeze by with the stock alternator and stock PS brackets....just with the F250s and so on will usually have to get aftermarket brackets or make you some
-Watch what manifolds come on the 460 because some of the stock manifolds can't be used (according to the year of the engine). Usually van manifolds work.
 

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the 351m/400 has one really good thing about em

they make a awsome place holder for the 460

car exhaust manifolds are the problem

any truck or van manifolds from 73-87 will be fine

88-97 was efi stuff looks close to the same but won't swap with non efi but will work in 78-79 stuff if using the efi heads

using the 351m/400 towers with aftermarket insulators is not the best route but doable
 
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