Are you going to work it hard, with lots of WOT and heavy loads? If so, the 390 will not last as long as a 391.

Also, 390 motors range from the low compression (8s) PU motors to 10.5 car motors. Given the age of engine, it would be wise to tear it down and at least know what pistons are in it, and cam. A 10.5 GT engine with the semi-lumpy cam would not work very well. A low compression PU motor would work fine if it's not worn out.

An FT motor will have a front engine mount with the rear handled off the sides of the bell. An FE will have side mounts. That will make a big difference in how you mount it in that truck.

 

Nice looking tandem!!

Besides some front mount / front cover and exhaust porting issues, the 390 is a LIGHT duty engine and is not suitable for long term medium and heavy truck usages.

There are several differences, probably the main one being a much lower static compression ratio, the 390 will detonate itself to bits in short order when pushed pulling a heavy load. Way too much heat in the combustion chamber from the higher compression ratio and retarding the timing does nothing except kill any performance. With the lower compression ratio of the FT engines, you can still run a decent amount of timing without detonation. It also helps with exhaust heat, retarded timing from a misapplication of a light duty engine in a medium / heavy truck means the fuel can still be burning when it exits the combustion chamber which is hell on exhaust valves and exhaust systems.

ALL manufactures of medium and heavy gasoline truck engines had lower static compression ratios to give a reasonable service life in heavy service.

Unless you are just building a hobby truck/toy that will never haul a load that is, if that is the case well then a higher static compression ratio would work.

David

 

I plan on using it for work and to pull this trailer and my 31AA

 

Another very nice truck --- sounds like you really need to find a proper FT motor, or consider a diesel swap?

How many miles a year are you thinking? What kind of GCWR are you thinking?

As far as work, what kind? It is awfully hard to make money with the amount of fuel these gas trucks consume, but then you would not have a truck payment and that offsets the fuel cost somewhat. It also hard to make money at the slower speeds these gas powered trucks have in comparison to the later model trucks - one hill I regularly go up at 7-12 mph I get passed like I am standing still by all the other dumps. They can get to the job site, dump and be back for a second load before I even get there with the first!

Just some random thoughts....

David

 

I will be pulling about 16,000-24,000 pounds
I am a builder so I will be carrying lumber and tools.
I plan on putting in a diesel in it some day . I just want to through in a391 for now. I picked up the 390 today and I think i'am going to what to rebuild it. I have a lead on two 391's one mite be a 361

 

If you are rebuilding that 390 that you are installing -- consider this upgrade to FT specs in regard to pistons /compression ratio / change to FT heads intake and exhaust manifolds. This would give you the reliability of the FT. A diesel would be the ultimate upgrade but you would lose the exhaust sound of a dual exhaust FT pulling a load --- nothing like it.

Just A Thought ------- Hotwrench

 

 

I picked up a 391 ft out of a 77 l800 today . I will clean it up and post the casting numbers to confirm . I got there a little early and had to help pull it out of the truck.
So... I took out the truck front and back cross members ,the engine mounts, starter ,flywheel ,everything on top and out front ,took the bell house and everything around it too. The guy hand a 60's ford coe with a I think a big block in it too. The casting number is( dt4e1) is it a ft or a fe motor?
I am stopped for dinner in Madison Wis. The motor was about 30 minute north of Eau Claire Wis.in Boomer . I will post some photos tomorrow .

 

I started cleaning the 391 tonight and found a rc tag?
RC-26
33738
What dose that mean?

 

Maybe the engine was rebuilt by a large rebuilder and that is their ID tag for warranty purposes.

 

I can't see your pic right now, but posts 13 and 15 in this thread show, in 13, a TAM rebuild tag, which is explained in other posts, and in 15, more engine ID info.

https://www.ford-trucks.com/forums/1...-for-f600.html

IIRC, your tag looked similar to the TAM tag. I can't find a list of Ford engine rebuilders like TAM. TAM is out of business btw.

Other tags on rebuilds show the overbore and crank rod and main undersize, such as 30-10-10 or similar.

 

Seller does not know what he has, claims FE, but the exhaust manifolds and distrib tell another story. In Minnesota. Did you follow up on the nice F 700-F900 fenders ? http://www.ebay.com/itm/65-66-67-FORD-352-FE-ENGINE-MOTOR-/131194332002?pt=Vintage_Car_Truck_Parts_Accessories&hash=item1e8bcaa362&vxp=mtr

 

Oil pan too. I do not see the front motor mount on the front cover, but then I do not see a clear enough pic for that...do you?

That green paint on the block might be rebuilder paint, seems I recall seeing green like that before. Not the Tam 292 my dad got, but maybe some other Ford engine.

 

Oh wait, OP has a motor. He has so many threads going on this it's hard to keep track. Needed a bell, might have a bell, beats me.

https://www.ford-trucks.com/forums/1...r-a-np540.html

https://www.ford-trucks.com/forums/1...-build-11.html