Cast Iron vs. Aluminum Head

hudsonguy

I was just wondering what some of experiences are that people have had with the optional aluminum head on the 262 motor. I've got the stock cast head on my '49 Super now, and somewhere along the line purchased a nicely reconditioned Clifford aluminum head. I know the spark plugs are different, and there also appears to be a water jacket in the head (at least there are two ports).



Would it be worth my time to switch for no reason other than to slightly improve my performance? I've heard that corrosion can be a problem what with the dis-similar metals and all.



I appreciate any and all advice,



Thanks,

Doug

brnhornet52*

Hi Doug,

Its fairly well documented that the stock aluminum heads were very troublesome in their heyday. They tended to warp, crack, and corrode and were largely made of pure aluminum from Alcoa. Modern heads have other ingridients to help overcome these problems.

You might be better off having your iron head milled to obtain the higher compression than going to the aluminum head. I'm not familiar with the Clifford head as to reliability.

Park_W

Another "cast iron solution" would be to put a 232 head on it.

[Deleted User]

I've collected several different heads of Hudson origin, and I like the factory aluminum heads the LEAST. The Alcoa aluminum seems to be of no alloy at all beyond the pure stuff. You can actually scratch the finish of the head with your fingernail if you lay into it hard enough. The up-side is they TIG weld beautifully! The downside is that the coefficient of expansion is HUGE! (meaning the amount they expand and contract during a heat cycle). That dimentional difference makes gasket sealing a nightmare.



The cast iron on the other hand has a very low coefficient of expansion relative to the Alcoa aluminum (meaning they change dimentions the least during a heat cycle). For the long haul and gasket longevity - the cast iron is best. Actually I believe the 55/56 engines had cast steel heads and would represent the best situation possible.



As far as the Clifford head is concerned, I have no idea what the alloy was that went into that head. But, aluminum alloys have come a long way since the Alcoa/Hudson era as evidenced by the widespread use of aluminum alloys in most any area of engine technology you want to explore. I was told that the combustion chamber of a Clifford head was a copy of the 262 cast head with the exception of spark plug location. I do know that a 55/56 - 308 cast steel head has the exact same profile and combustion volume as a 262 head. I did talk to Jack before his passing regarding his head but didn't know enough about the different heads to ask about the 262 combustion chamber. Basicly, what he did tell me was that his head differed in the amount of material surrounding the combustion chamber for owner modifications such as high lift cams and additional grinding/profiling of the combustion chamber. The spark plug relocation was to help with the detonation/pinging so prevalent with the Hudson, and that eliminating the exhaust heat to the intake manifold and replacing it with water heating did more to stop that than plug location.



I have 4 different 308 engines, all of them had 262 type/profile heads on them. I'm suspect of the real 7x 232 heads as I believe they were hand polished/surfaced out to a 262 volume, or at least increased in volume somewhere between a stock 232 and 262. I may be corrected on that belief, but most of the people I've talked to who attempted to run a 232 head on the road were not happy folks (too much pinging and didn't notice any real gain in performance). Evidently, there is a good balance between performance and reliability in the 262 head used on the 308, and that's probably the same route I'm going to take on my own long haul engine.



All that being said, I would be interested in your Clifford head should you choose not to use it. The reason being I don't have one and I'm about to start flow bench testing different combustion chamber profiles machined in acrylic ( using some things I've done in other flathead engines). The stock heads don't have enough material in the areas I'm working with and the Clifford does. Rather than junking a bunch of heads in search of El-Dorado, I'm using the acrylic so an actual head can be cut right the first time.



My $.02



Mark Hudson