I believe most aftermarket heads are cast from A356 aluminum but I'll check
that. All you metallurgy enthusiasts can dig into the thermal expansion,
corrosion resistance, and thermal conductivity properties as deep as you like.
The Japanese and Europeans (except the Italians) figured out how to cast
aluminum and build engines with it (including iron blocks and the associated
electrolytic/thermal expansion issues) long ago. Why would it be a problem here?
Theo Smit
tsmit@home.com
tsmit@novatel.ca
B382002705
> -----Original Message-----
> From: James Barrett [SMTP:jamesbrt@mindspring.com]
> Sent: Tuesday, August 03, 1999 5:19 PM
> To: Michael M. Kelly
> Cc: tigers@autox.team.net
> Subject: Re: Aluminum heads
>
[] <snip>
> Michael,
> I had stock aluminum heads on a 3.8 L Mustang and twice the
> heads(combustion chamber) corroded into the water jacket. I was very
> careful to keep fresh antifreeze/ water mixture in the Mustang, but it
> happened anyway. I have also noticed a similar problem with
> Aluminum manifolds where they contact the coolent. The aluminum
> heads can be TIG welded and remachined much cheaper than a
> cast iron head. Most after-market aluminum head manufactures claim
> better performance than the stock cast iron heads.
> The lighter weight is also an advantage.
> You pays your money and takes your chances.
>
> I talked to an old Mercury outboard repairman and he
> stated that Mercury had added copper to their aluminum alloy
> to make the alloy easier to cast. This copper within the
> alloy caused self electrolis of the casting when in contact
> with water. Susposedly Mercury finally changed the alloy
> to solve the problem. My guess is that the head manufactures
> are more interested in low cost casting than long life alloys.
>
>
> James Barrett Tiger II 351C and others
>
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