What engine to swap to?
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Senior User
Joined: Apr 2004
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From: Spokane, WA
What engine to swap to?
I have a '78 F250 Crewcab 4X4 with a C6 and 400, 4:10 gears. I need some opinions as to what would be my best swap for power as well as economy. I am nervous about just building the 400 mainly because of the bad rep these motors have. I am also considering installing a Spicer 3 speed behind the transfercase to the rear wheels to get overdrive when in 2wd as well as 50% underdrive at the rear wheels for use in the woods when it is not muddy. What do ya all think? Is it best to build the 400? Go with a 429? Has anyone installed a spicer to get the 25% OD at the rear wheels?
Thanks
Thanks
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Joined: Jun 2005
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From: Dunmore Pa.
I never did the transfer case thing you are doing but I did put a 460 in my 77 F-250 4x4 best move I ever made it ran 100 times better than the M I had and got almost the same MPG
Good luck with your swap
Glen
05 F-350 4x4 Reg Cab PSD 6Spd.
Good luck with your swap
Glen
05 F-350 4x4 Reg Cab PSD 6Spd.
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
i second a 460 swap. great torque down low which will help move that heavy rig and way better mpg then your 400. my uncle has a 76 cc with a 390/C6 4.10's. he definatly needs 4.56 gears and a 460 because of the weight of the truck. the easier the motor works the better life and mpg youll get out of it for sure. nice thing is you can keep your tranny if going to a 460. my uncle would have to swap his tranny out which sucks. i agree building the 400 would cost more then going the 460 route
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From: Dunmore Pa.
Too really sell the 460 swap which I belive will put a huge smile on your face I read somwhere that the 351M/400 has half a HP per cubic inch and it can't breath very well. With those numbers I can't see wasting any time building a 400
When I did my 460 swap my friend got totaled in his 73 town car and I took his engine no idea how many miles were on it but when we pulled the covers it looked very nice so we painted FORD Blue put a holley and headers on and I got the other swap parts then slapped it in no rebuild at all and even like that it walked all over my M trust me 429/460 is the way to go.
When I did my 460 swap my friend got totaled in his 73 town car and I took his engine no idea how many miles were on it but when we pulled the covers it looked very nice so we painted FORD Blue put a holley and headers on and I got the other swap parts then slapped it in no rebuild at all and even like that it walked all over my M trust me 429/460 is the way to go.
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Joined: Jul 2005
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From: Hillsboro,Oregon
Originally Posted by gp42gpw
Too really sell the 460 swap which I belive will put a huge smile on your face I read somwhere that the 351M/400 has half a HP per cubic inch and it can't breath very well. With those numbers I can't see wasting any time building a 400
When I did my 460 swap my friend got totaled in his 73 town car and I took his engine no idea how many miles were on it but when we pulled the covers it looked very nice so we painted FORD Blue put a holley and headers on and I got the other swap parts then slapped it in no rebuild at all and even like that it walked all over my M trust me 429/460 is the way to go.
When I did my 460 swap my friend got totaled in his 73 town car and I took his engine no idea how many miles were on it but when we pulled the covers it looked very nice so we painted FORD Blue put a holley and headers on and I got the other swap parts then slapped it in no rebuild at all and even like that it walked all over my M trust me 429/460 is the way to go.
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Joined: Nov 2003
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From: Alberta
The factory never gave the 351/400 much attention due to emission crap. Put a small 2 barrel carb and retarded valve timming on any engine and it will suck. All you need to do is add an intake with a good 4bbl carb, camshaft, and a performance timing chain/gear set. And that 400 will rock! If you really want alot of power bump up the compression and add headers. Everyone that I have spoken with that has built a 400 loves it. A built-up 400 will give a 460 a run for its money and get better gas milage. The 400 is also lighter (351/400-575 pounds....429/460-720 pounds).
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Hotshot
Joined: Jul 2002
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From: Bend,OR
you have to do a lot more to a 400 then what you said to get gains like that and it will never get better mpg then a 460 thats a pipe dream if i ever heard one.
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From: Dunmore Pa.
You can build the 351M/400 all you want and it will not compare to the 429/460.
I had a M with a 4 barrel Holley headers Mallory ignition and it still could not get up and go. It just can't make the power maybe if I added heads and other goodies it could but the 460 that replaced it was right out of the 73 town car it proabably had 75-80 thousand on it and in stock form walked all over the M with the same MPG. After the swap I would never even try to do anything to a 315M/400 but take it out.
This is just my opinion after having both.
Good luck on whatever engine you use.
Glen
05 F-350 4x4 Reg Cab PSD 6Spd.
I had a M with a 4 barrel Holley headers Mallory ignition and it still could not get up and go. It just can't make the power maybe if I added heads and other goodies it could but the 460 that replaced it was right out of the 73 town car it proabably had 75-80 thousand on it and in stock form walked all over the M with the same MPG. After the swap I would never even try to do anything to a 315M/400 but take it out.
This is just my opinion after having both.
Good luck on whatever engine you use.
Glen
05 F-350 4x4 Reg Cab PSD 6Spd.
Freshman User
Joined: Sep 2004
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From: Malmo minnesota
underestimaters
First of all a 73 460 is a great un-smoged motor so thats why it ran so great, put a 79 460 against a 400 with a mallory ignition, 4barrel, cam, headers and i bet ya that the 400 would take it.
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Joined: Jul 2002
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From: Bend,OR
Originally Posted by minnesotasix
First of all a 73 460 is a great un-smoged motor so thats why it ran so great, put a 79 460 against a 400 with a mallory ignition, 4barrel, cam, headers and i bet ya that the 400 would take it.
Post Fiend
Joined: Jan 2003
Posts: 8,600
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From: Iowa
I say build up a nice 390 for it. You can get more power out of it than you'd ever need on the street, and they weigh less than a 460 (you wouldn't have to change out springs). You can get over 400hp and 400ft-lbs without too much effort, and has been done and proven many times, myself included, over on the FE forum. Also, my 390 equipped F100 will get 15mpg on the highway. Not that I've got anything against 460's, I just like my FE's.
Edit: The transmission might be an issue, although there are plenty of FE equipped trucks out there with a C6, so it shouldn't cause too much of a headache.
Edit: The transmission might be an issue, although there are plenty of FE equipped trucks out there with a C6, so it shouldn't cause too much of a headache.
Last edited by rusty70f100; Sep 21, 2005 at 03:50 PM.
Senior User
Joined: Dec 2002
Posts: 339
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From: Washington ,Mo.
If it is a 3sp aux.spicer 5831.B 1st is 2.35:1 2nd is 1:1 3rd .85:1 OD.I had one in my truck for 3 or 4 years they are noisy leak gear lube.I over hauled it and had a shop do it also they told me that it was going to start to leak again those did that when they were new from the factury.They weigh about 250.
Dale
Dale