Aluminum vs. cast iron heads

[Alan O'Connell]

What is the advantages of aluminum heads over cast iron heads. I know the Fords in the early and mid 1930's came off the assembly line with aluminum heads.

 

[itslow]

They look neater. That’s really about it for the stock heads, though. Some of the aftermarket ones may have better combustion chamber shapes, plug placement, etc.

 

[drolston]

Aluminum heads are about half the weight of cast iron. Aluminum conducts heat about four times better than cast iron. I suspect that both factors played into the decision to use aluminum heads on early flatheads. But the economics were not worth the minimal benefits.

 

[CA Victoria]

FWIW-Cast iron heads can be milled to get an improved CR.
I have put a lot of time into fitting “new” aluminum heads made by a well know engine builder in Calif. The overall quality looked good but that’s where it ended.
Both heads were not milled correctly, both head would not fit over head studs (I have two NOS 59a ford heads that did fit perfectly)……CC’d the heads and the same two chambers were way-way off (mfg casting difference). Corrections are not reasonable for the average home shop.
Hindsight being 20/20 I would put the work & $$$ into OEM 59a heads. So far I would say that the gain is not worth it.
I am stunned that an engine builder would accept the quality that I found in these heads.

 

[highbeams]

Yes. My '33 aluminum heads replaced in the '40s?. description of the cast iron heads on it now . . . driver side = 12 19 45 886050B; passenger side= 5 23 47 886049B
********
the orig flathead 221 ci with oil tube to the throw-out bearing. thank you -

 

[SoCalCoupe]

Done A LOT of research on this. Aftermarket aluminum heads usually look pretty cool. Performance-wise, the differences are trivial. There are some things that can be done to squeeze some extra performance out of a flathead but aluminum heads are WAY down on the list.


For flathead performance, I highly recommend the book Flathead Facts by the late John W. Lawson.


For looks, it's your call. If you decide to go with aluminum heads be sure you know whether or not the stock head bolts will work. If they won't, and you have to replace the head bolts, I highly recommend not attempting this with the engine in the car. Ask me how I know.