Hello folks
I am going to dissasemble a 76 f250 4x4. The motor is a 390 that needs rebuild. This motor has a 4 barrel cast intake. Are these motors worth keeping cuz they are getting a bit rare? Plus, is the 4 barrel intake hard to come by and were they put in a 4 wheel drive vehicle??

thanks

 

Four barrels mostly came in cars and 360's came in four bys.Your 390 is probly a dealer option or was swaped in.
The old FE motors made good power and great torqe at the price of fuel economy.Parts are getting easyer to come by for the sake of a growing aftermarket that is finely catching up.
I love the FE motors,they respond greatly to hop up parts such as aluminum intakes,cams and headers.

 

make sure it is really a 390. they all look the same from the outside.

 

You will need to check the casting numbers on the head and on the crankshaft when you get down to rebuilding. The numbers will need to be cross referenced to a reference book to determine the engine size. I have a cross reference book, send me an e-mail and all cross reference the numbers if you like.

 

Moved to engine forum.

 

Numbers - Shmumbers , The easiest way to check is to pull a spark plug out and use a piece of coathanger to measure the stroke. 3.50" - 360 --- 3.78" - 390.

 

The cast 4 barrel intakes are all over the place. That is because most folks remove them for the lighter aluminum intakes.

In your application, the 390FE engine is just about perfect. The only two other engine's I would even consider is another FE in the 428...or go with the big 460. But for all around use, the 390 is a great engine. If you are rebuilding it any way, then you might want to upgrade while there. The best upgrade would be a cam...

JMHO...good luck with the rebuild!

 

The 390 motor is definately worth keeping. I'm fairly sure they didn't put 4 barrel's on 360's. Stranger things have happened and I could be wrong, but if he has a 4 barrel I'm 95% sure he has a 390.

A few things to keep in mind when rebuilding:

1. A motor is a system. Dont expect to upgrade just one thing and have it do much.
2. When upgrading, keep in mind what you want the truck to do. Example: Dont put a race cam and a 850cfm double pumper in a work truck.
3. Keep your upgrades matched. Example: Dont use a race cam (or any aftermarket cam for that matter) with a 2 barrel.
4. Remember, if the engine is old and needs to be rebuilt, all the stuff around it probably needs some attention too. Distributors get worn out, alternators, coils, radiators... All this stuff can make you wonder why on earth you ever messed with the engine. If you're going to do it, do it right.

Now then, here are the major restrictions for a truck 390:
1. Exhaust manifolds - Most restrictive design EVER. Replace these with headers at all costs. If you do nothing else, do this.
2. 2 barrel carb and intake - You dont have to worry about this one, since you have a 4 barrel. You can keep your carb if it's rebuildable, but I'd get a Holley. On the cast iron vs. aluminum thing, the cast iron 4 barrel intake is entirely adequate for a working truck like a F250. I think you also avoid a lot of gasket problems as well...
3. Cam. After you've addressed #'s 1 and 2, you can start worrying about the cam. Since you're rebuilding, you may as well put in a decent cam. The stock grind isn't really all that bad, but it is 30+ year old technology. The Crane 343901 would be my choice. You'll probably want to convert to adjustable rockers to avoid problems.
4. Pistons. The truck FE motors had pathetically low compression, especially when rebuilt with Fel-Pro composition head gaskets. Get some good higher compression pistons. TRW L2291's are good for most 390 builds. Vary your head gaskets for your target compression ratio.

Probably more than you ever wanted to know.