Jim, MANY thanks for giving us some solid documentation on the above
subject.
>From this it appears that the 355 T6 that Zora used for his Ardun
castings is indeed a stronger casting aluminum than the 356 T6
universally used today, in permanent molds at least. I'm pretty sure
our original Arduns were all sand-castings, however, which I imagine
have inherently slightly less strength.
The figures in your Alcoa tables suggest that the A356 T6 which GM is
reported to be using for their brand new 270 HP inline Six is rated at
the same tensile strength as the 355 T6, 37,000 lbs. For comparison, a
1018 low carbon steel we commonly use in racecar construction has about
50,000 lbs tensile strength. I gather that these figures refer to the
amount of weight a one inch square test bar can support before failing.
Most likely, the consequences of tensile strength in aluminum castings
would mainly be in how much stress plug threads and threads for head
bolts, etc, could take before giving way. Obviously the head bolt
threads are a critical item. So are the main bearing bolt threads. If
these don't keep their integrity, it's sayonara, baby.
Anyway, I guess we can take from this that Zora was using the best
aluminum casting alloy available for his Ardun heads, which would be
very becoming to a professional engineer, needless to say.
I'm still delving into the mysteries of original production of the Ardun
heads. From various sources of info that are still appearing, it may be
that after Zora made his first prototypes in 1947 in New York, he may
have only made and sold a dozen or two dozen more sets in the next
couple of years, as Ardun Mechanical Corp., and then as he told me, he
made arrangements with the Associated Equipment Company Ltd. of England
(famous maker of double-decker buses) to continue the manufacturing,
because "high class engineering could be done there for 1/3 the cost in
New York." Zora told me the capital to set this up came from his own
company.
In 1950 Ardun Manufacaturing Corp. has disappeared, next Ardun Engine
Co, then Ardun Power Products Corp. has appeared, selling and
distributing Ardun equipment also from New York. Sometime this year, it
appears Zora goes over to work for Allard in England, where he stays for
a couple years. Allard literature of the period claims to be "Sole
Manufacturers and Concessionaires of Ardun Equipment. Home and Export
Sales."
So there are some mysteries there for Ardun fans. A writer named Jerry
Burton is said to be working on Zora's authorized biography at the
moment for publisher Robert Bentley, with the co-operation of Zora's
widow Elfi, and access to Zora's personal files. The book may be out by
the end of this year, I'm told. I look forward to seeing that book in
hopes it may put the Ardun story into clearer focus.
A newspaper story about the introduction of the Ardun heads appears in
the New York Times sometime in 1947. It is filed in the New York Times
Index for 1947 under Ardun Manufacturing Corp. I am presently trying to
track down a copy of this article, in case anybody reading this has
same. Little bit of detective work. Cheers Bill
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