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Discussion Starter · #1 ·
i have a 68 xl convertible with a 390 and 4 speed. the block is cracked. i found a 390 from a truck. is there any difference between these engines.
 

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If the engine is out of a p/u truck: Same. If it is out of a big truck it would be a Super Duty 391ci so the answer is no.
 

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There should be no difference in the truck block at all. The 64 and earlier blocks are different as they only have one set of motor mount holes. It should be a direct swap.
 

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Discussion Starter · #4 ·
are the heads and cam the same, what i am getting at is will the performance be the same. its not driven like a race car, just to shows
 

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I wanna say that the only reason it is a 391 is to designate it truck, actual size and block everything is same. I just thaught I heard this somewhere. It's like when they changed the 396 chevy to 402 but still badged it 396? Good luck to ya.
 

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nope..

An actual 391, like the 331 and 361 will have a different set of heads that will NOT work with any aftermarket, or for that matter standard car and truck heads. They use a different timing cover with a water pump more like a 302/351w than an FE. Even the hole for the dist shaft is larger, requireing a bushing or an FT (ford truck) specific distributer.

If the 390 your looking at was in an F-350 or smaller truck, you should be fine. Probably be a little lower in power, especially if its a low compression post 72 motor, but it will run fine.
 

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Discussion Starter · #7 ·
this engine was out of a pick up, nothing like an f350.
supposed to be before 1972. so it should be ok. i hope
 

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If the engine is good get it. The 72 model engines were before the 1974 gas crunch and have a little higher compression ratio. It will be okay for a cruiser and drive to shows. No one will know that is a truck engine unless they check the casting numbers.
 

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About 8-8.5 to 1 compression, make sure it is indeed a 390 as the 360's look the same. Measure piston stroke....other wise you will notice the lack of power.

_________________
1962 Galaxie 500 - My High School Cruiser in 76, but much faster Now!

<font size=-1>[ This Message was edited by: Galaxie_406 on 3/29/06 11:37am ]</font>
 

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No, the truck pistons are different between the car and truck 390. The truck 390 uses the 410 piston that lowers the compression to 8:1 and widens the quench the extra .100 the compression hieght differs. Outwardly the differences are as stated above. Keep in mind that trucks have usually had a hard life, and if they are in a junkyard, well...

The good news is that you can rebuild it with the right pistons and it will be a nice 9.5:1 motor. Pick out a better cam and get a good three angle valve job and it will be a very satisfying engine.

If you are looking for the best junkyard engine, get a '68-'70 390 2V regular fuel engine out of a Galaxie. They have the torque cam 256°/266° adv duration 192°/198°@.050 .427/.431 lift 113 LSA, dished pistons, and fast burn heads. If you recurve the distributorm put a set of headers on and a 4V manifold you'll like the idle-4500 rpm power it makes. It is much less likely to have had a hard life too.

<font size=-1>[ This Message was edited by: BillBallinger on 4/2/06 7:51pm ]</font>
 

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On 2006-04-02 04:35, BillBallinger wrote:
No, the truck pistons are different between the car and truck 390. The truck 390 uses the 410 piston that lowers the compression to 8:1 and widens the quench the extra .100 the compression hieght differs. Outwardly the differences are as stated above. Keep in mind that trucks have usually had a hard life, and if they are in a junkyard, well...

The good news is that you can rebuild it with the right pistons and it will be a nice 9.5:1 motor. Pick out a better cam and get a good three angle valve job and it will be a very satisfying engine.

If you are looking for the best junkyard engine, get a '68-'70 390 2V regular fuel engine out of a Galaxie. They have the torque cam 256°/266° adv duration 192°/198°@.050 .427/.431 lift 113 LSA, dished pistons, and fast burn heads. If you recurve the distributorm put a set of headers on and a 4V manifold you'll like the idle-4500 rpm power it makes. It is much less likely to have had a hard life too.

<font size=-1>[ This Message was edited by: BillBallinger on 4/2/06 7:51pm ]</font>
OK - so are there are any details on the "410" pistons.... I assume that these are basic cast pistons - not something forged. I am daydreaming about finding out that the truck moters had heavy rods, forged pistons and 8:1 compression as a cheap bolt-in replacement for my 352 under the 60MM turbo that is going on....

_________________
'65 Custom 2 Door Project Car

Remembering to live Coram Deo

<font size=-1>[ This Message was edited by: 65Custom on 4/5/06 5:07am ]</font>
 

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The 410 piston is just like the 3902V dished piston, but it was designed for the 3.98 stroke. It has the pin .100 higher, making the piston come up .100 lower in the bore on a 3.78 stroke engine. This was done on truck engines to lower compression, but it also killed efficiency by taking away squish/quench. It is a cast piston and is of the same strength as any other Ford piston.

Light truck engines really didn't get anything special, the 360 used the same skinny rods as the 352, and the 390 got the same rods as the car, however the are good rods for about anything within reason with good bolts. They are getting old though, so have them inspected.

Hope this helps.
 

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I am in a similar position, I am supposed to go pick up a 390 out of a 1970 f250 this weekend for my 65' galaxie. It was rebuilt about 6k ago, has edelbrock heads, carb and intake, and electronic ignition... I am a bit concerned it will be a dog, but for $350 bucks I can't really complain.
 

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On 2006-04-05 05:46, BillBallinger wrote:
The 410 piston is just like the 3902V dished piston, but it was designed for the 3.98 stroke. It has the pin .100 higher, making the piston come up .100 lower in the bore on a 3.78 stroke engine. This was done on truck engines to lower compression, but it also killed efficiency by taking away squish/quench. It is a cast piston and is of the same strength as any other Ford piston.

Light truck engines really didn't get anything special, the 360 used the same skinny rods as the 352, and the 390 got the same rods as the car, however the are good rods for about anything within reason with good bolts. They are getting old though, so have them inspected.

Hope this helps.
It helps a lot. Thanks much...
 

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On 2006-04-05 11:26, jgnatek wrote:
I am in a similar position, I am supposed to go pick up a 390 out of a 1970 f250 this weekend for my 65' galaxie. It was rebuilt about 6k ago, has edelbrock heads, carb and intake, and electronic ignition... I am a bit concerned it will be a dog, but for $350 bucks I can't really complain.
If you aren't happy with it I'll buy it - PM me for my address.

Seriously though - There would have to be a WHOLE LOT wrong with it for it not to be a great deal if it really has Edelbrock heads (assuming aluminum) on it and is a 6K old rebuild. Outside of the the heads both being cracked you are probably in good shape.

_________________
'65 Custom 2 Door Project Car

Remembering to live Coram Deo

<font size=-1>[ This Message was edited by: 65Custom on 4/7/06 12:43am ]</font>
 

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Came to get the engine and it was sitting out in the rain on the bent hoist, couldn't be moved or raised into my truck so I have to go back with my hoist and get it. So I guess its going to be time for another rebuild... any recommendations for new pistons/cam?
 

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All depends on you, first you need to sit back and think what kind of performance do I need, am I a cruiser or a racer or do I want both? Regular gas, Premium or Premium + Booster then you need to set a budget to work with and figure $500 min for the things you forgot.

My 390 is a cruiser, I started with a 70 LTD block that needed to be bored to .040 to clean it up, pistons were hyperutetic Speedpro 381p about 9.6 to 1, chromemoly rings, clevite 77 bearings, high volume oil pump, oil block mods, trw lifters, decent RV cam but should have went Compcams high energy, resized rods (stockers), roller timing chain, 64 Ford cast 4 bbl intake, exhaust port matched, exhaust logs ported and relieved and gasket matched, (soon to get cast headers) Holley 600, heads rebuilt with 3 angle valve job and hardened exhaust seats (not necessary if cruising, only if pounding the motor) fully integrated Ford electronic ignition with TFI coil. So that's my combination yours like a chefs soup will be differnt depending on the seasonings.

_________________
1962 Galaxie 500 - My High School Cruiser in 76, but much Faster!

<font size=-1>[ This Message was edited by: Galaxie_406 on 4/10/06 12:04pm ]</font>
 

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definately want it to be faster than just a cruiser, and i don't have a huge budget either. (i know... i know..) id like to know what others have found to work however, galaxie_406, thanks for your info.
 
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