swap questions
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Freshman User
Joined: Jun 2005
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swap questions
ok here it is i have a 78 f250 with a 390 in it i am putting in a 351c or 351m im not sure witch it is yet i have not picked it up yet what do i need to change or does it just drop in. any info is helpfull thanks.
Lead Driver
Joined: Apr 2001
Posts: 6,175
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From: Texas
Definitely not a drop in! You'll need a different transmission or at least a bell-housing that mates to 351 you chose. I'm not sure, but I think the Cleveland and the M are different, keep that in mind when finding parts. You'll need motor mount perches for the 351. You'll probably need a different length drive-shaft and to relocate the transmission cross-members as it's position will most likely change.
I'm sure I've missed a few other items.
That being said....WHY would you replace a 390 with a 351? If you're hoping for better mileage, don't bet on it.
I'm sure I've missed a few other items.
That being said....WHY would you replace a 390 with a 351? If you're hoping for better mileage, don't bet on it.
Fleet Owner
Joined: Jan 2004
Posts: 26,007
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From: Brentwood,CA
well you will run into problems because in order to get the 390 in there now the po probably cut up alot of stuff because a 390 was not a option after 76. keep the 390 if thats what you have now.
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well the 390 is toast lots of water in crankcase and i pulled intake manifold and there is rust on pushrods and rocker arms. im guessing its a 390 it looks like all the descriptions of the 390 and the intake says edlebrock performer 390 on it.
Lead Driver
Joined: Apr 2001
Posts: 6,175
Likes: 21
From: Texas
I think they offered the FEs in the F250/350s up until 79. I could be off my rocker again.
Anyway, it sounds like it needs to be pulled apart and rebuilt. you can find running 360/390 FE engines for a decent price. They would be a drop-in replacement for less than what you would spend adapting a different motor. Or, you could rebuild the engine you have.
is this your daily driver, are you in a hurry, what's your budget?
Anyway, it sounds like it needs to be pulled apart and rebuilt. you can find running 360/390 FE engines for a decent price. They would be a drop-in replacement for less than what you would spend adapting a different motor. Or, you could rebuild the engine you have.
is this your daily driver, are you in a hurry, what's your budget?
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Fleet Owner
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From: Brentwood,CA
my bad, please ignore the comment about the ft engine i put that there by mistake i forgot this thread was about the 78 ford and not about the f600 dump truck. sorry.
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Fleet Owner
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From: Brentwood,CA
FTE Leadership Emeritus
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From: Long Island USA
Originally Posted by gtex
I think they offered the FEs in the F250/350s up until 79. I could be off my rocker again.
FTE Leadership Emeritus
Joined: Jul 2002
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From: Long Island USA
Originally Posted by tazf250
do i nee to put intake back on to do comp. test?
IT'll be a "cold" compression test, but that's OK...
Postmaster
Joined: Nov 2002
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From: Littleton, CO
Originally Posted by gtex
Definitely not a drop in! You'll need a different transmission or at least a bell-housing that mates to 351 you chose. I'm not sure, but I think the Cleveland and the M are different, keep that in mind when finding parts..
--Mike
Post Fiend
Joined: Jan 2003
Posts: 8,600
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From: Iowa
I say forget the 351, M or otherwise. The 390 will be a much better engine IMO. Others have outlined the problems that swapping will cause. A little rust means nothing, a quick trip to the hot tank and all that will be gone.
I say rebuild the 390. It's probably just a gasket that let the water in. Tear it down and find out.
I say rebuild the 390. It's probably just a gasket that let the water in. Tear it down and find out.