390 aluminum heads

[390owner]

Other than weight was is the advantage of aluminum heads for a fe 390. I am wanting to get mine rebuilt and the machine shop suggested aluminum heads.

[machoneman]

Money! Ask your shop for the total cost to fix up your iron heads. You may be surprised how close it comes to new, slap them on, aluminum heads.

[My427stang]

More airflow, easier to repair, not much cost difference over rebuilding iron, all new parts.

However, be sure to note application, all alum heads use the early/CJ exhaust port location.  If replacing D2, C8AE-H or some other unibody designs, AND using headers, the exhaust ports may not hold a gasket.  Not as much of an issue with manifolds

[chris401]

Other than weight was is the advantage of aluminum heads for a fe 390. I am wanting to get mine rebuilt and the machine shop suggested aluminum heads.

Shop around for a fair comparison. Around here $650 gets a quality iron head rebuild. I have never owned an aluminum set of heads but there are many post on more recent years of Edelbrock castings and the work needed out of the box. I know with aluminum you can get away with less timing.

[390owner]

I have headers and will continue to use them. Did not know there might be a problem with them and alumiumn heads

[TomP]

Only a problem with some headers that use the lower exhaust port. Easy to check, on the lower ports the bolt holes are about the same distance above and below the tube. On the higher ports, like the aluminum heads use, the upper bolts are closer to the tube than the lowers.

[My427stang]

I have headers and will continue to use them. Did not know there might be a problem with them and alumiumn heads

It depends on the headers original application.  If they are truck headers or 390GT, they are usually designed for a port about .250 lower.  If they are designed for CJ or early FE heads in a car application, they will be the same as the aftermarket heads.

The issue is only gasket compression around the port, if you use the wrong headers, the gasket isn't compressed on either the top or bottom (depending on the mismatch).  With manifolds and flat ground header flanges, it's just a little mismatch

What is the head casting number you are replacing and what is your 390 in?

[My427stang]

Just saw on another post that you have a 79 Bronco if this is the same application.

Depends on the header you are running.  Hedmans are for low port, Hooker truck headers should be the same.  FPA can be made for either, and Mad Dog can also be made for either.

[390owner]

Yes the 390 is in my 79 bronco. It is around a 76 truck 390 with headman headers.  What about gas mileage. When the engine was rebuilt about 18 years ago I was getting 10-12 miles per gallon and 7-8 towing my camper. Now I get 8-10 and 4-6 towing. I want all the power I can get but maybe  back to the 10-12 range on the mileage.

[My427stang]

Yes the 390 is in my 79 bronco. It is around a 76 truck 390 with headman headers.  What about gas mileage. When the engine was rebuilt about 18 years ago I was getting 10-12 miles per gallon and 7-8 towing my camper. Now I get 8-10 and 4-6 towing. I want all the power I can get but maybe  back to the 10-12 range on the mileage.

Well, hard to tell, I would say that an 18 year old engine could need a timing chain by now, not to mention there has been some significant changes in camshaft, intake and quench knowledge for street use. 

I will say though, I do not expect your headers to have a good seal with alum heads, unless, in the very least, you slot all the top holes and raise them as much as you can.

For mileage, I would calculate your exact compression, run the cam as advanced as you can, and make sure you have a matching timing curve.  12-12 should certainly be doable if you have headers, the right ignition curve,  and a good free flowing exhaust

[390owner]

The engine has 110000 miles on it. It runs great but I am sure it is needing a rebuild.

[chris401]

Other than weight was is the advantage of aluminum heads for a fe 390. I am wanting to get mine rebuilt and the machine shop suggested aluminum heads.

Shop around for a fair comparison. Around here $650 gets a quality iron head rebuild. I have never owned an aluminum set of heads but there are many post on more recent years of Edelbrock castings and the work needed out of the box. I know with aluminum you can get away with less timing.

Correction, the rebuild price was $650.