Hello everyone, looking for some ideas on what to do to upgrade my 390. My current 76 F.250 4x4 I have rebuilt and I have this 390 in it. When i got this truck about 3 years ago, it came with this new Jasper rebuilt 390 in it and an Edelbrock performer intake. So I finished up the truck build and finally got it on the road. About 4 months ago. Now after a mere 2000 miles the old gaskets from sitting are leaking. I have to add a quart of oil every 100 miles and the intake manifold continuously leaks coolant when driving. The other problem I have is that the truck has no *****. It runs good and will pull good, but wont go up a hill over 50 m.p.h. So now that winter is coming, I am planning on pulling the motor and doing a re-rebuild on the motor and adding some power to it. I plan on using this truck as a quick daily driver and occasional sled puller.

• Any ideas on a good cam to use on it?
• Also what is the stock compression ratio on a 390? I was thinking of shaving the heads to bump it up a little.

 

many of your problems may be a improperly fit intake.
also of note, shaving heads/block require comparable machine work to the intake.

 

That only depends on how much material was removed from the heads or block. Intake milling isn't a "given" after milling the block and or heads. Once you take it off, you can't put it back. A test fit should be done before intake milling. I do agree though that his intake leaking may be a problem with the performance, that combined with the questionable cam grind in a Jasper motor, plus the pistons they used in it, those are probably less than desireable as far as compression ratio goes.

 

Stock compression ratio ? Depends on the year and vehicle. It's anywhere from 8 to 1 to 10.5 to 1. I would shoot for the highter number and stick a Crane 272 Energizer in it. That combined with the stock heads (D2TE) will allow it to run on 89 octane fuel (at 12* initial timing) and the power band will run from idle to 5500 rpms. You didn't mention the carb, what's on it now ? Does it have headers ? That's a "must have" with any FE motor, the stock manifolds just don't do the job.

 

sounds like manifold was installed poorly , i'd buy a gasket set and remove manifold and clean everything up and reinstall being very careful .
oil leak plus coolant leak plus lack of power all could be the manifold not seating correctly
Have you checked how much vacuum engine has ? if so what was the reading ?

 

428 crank and you have a 410. Cheap cube increase.

 

I havent checked how much vaccum the engine has. I`ll have to stick a gauge on it before I tear into it too far.

Any idea on what kind of price head milling and intake manifold milling may cost?

It currently has manifolds with dual pipes. I`m gonna put on a set of Hooker long tube headers when I`m done. It currently has a 4bbl 600cfm Edelbrock Performer carbeurator, though I do have a 780 Holley sitting on the shelf.....

 

You'd need to check with your local machine shop for prices. I for one have never had to mill an FE intake, check it first before milling anything, chances are it needs no milling. Just me, but I'd use the 780 Holley, it's a better match for a 390 than the Eddy 600.

 

+1 ON 780 HOLLEY
i've had holley 600 , 600DP and a 750 on my 390 the 750 is what she likes

 

i have a 360 and am going to rebuild it. aq thought. get a distributer from a 75/76 fe it was changed to electronic. also like just about every one has sead change the intake gaskets befor doing any thing else have fun

 

WHAT??????????

 

Put new intake gaskets and check your timing advance, should be around 38deg total by 3000rpms.

 

That's what the "progressives" call "progress" in our schools. It's the thought that counts, not the actual results.

 

a small vacuum leak can rob all of your torque...
check for vacuum leaks and replace the intake gasket. bet it runs way better...

whats a compression test say? compression and leak down tests say alot! could be an easy fix, bide your time to build a bigger motor ya know! bout the same mpg no mater what! go big,

call the cam manufacturer they will have the best sugestions. check out comp cams,good fe selection.
shaving things on a fe can be a lil expensive, new flat top pistons probly cheaper and way easier...

good luck w/ the build... still tryin to start my over-built fe plan!!!