That's interesting Bill, I recall reading that Top Fuel dragster engines
twist their cranks 15 or 20 degrees end to end at full load. And that's
why their cranks have such a short service life before cracking.
The Flathead and Ardun crank, with three main bearings, whether Ford or
aftermarket, seems to be quite torsion-resistant and pretty rugged. It
never had nor needed a vibration-dampener.
The Ardun camshaft, on the other hand, is much better made of steel than
the iron that the Flathead is okay with. The difference is probably
that the Ardun almost always uses much stouter valve springs than the
Flathead, for obvious reasons. Theoretically, the closing forces of the
valve spring on the cam should balance the opening forces so that there
wouldn't be much difference in torque required to turn the cam. But in
practice it doesn't seem to be that way. One difference is the total
amount of valve spring pressure affects the drag of the cam in its
bearings. Chuck Salmen, owner of the $um Fun Roadster, mentioned a
couple years ago on this List that his aftermarket racing BB Chevy with
super-strong valve springs sometimes suffers from cam bearing failure,
which never happens with stock engines.
Iron Flathead cams are often used (but have been known to fail )in
Arduns, so since the C.T. Automotive days steel cams have been
recommended for them, if you could get ahold of one. Either a '32-'34
steel Ford Flathead V8 cam reground to more exciting lift and timing, a
Herbert or Moon steel roller cam, or an Isky steel billet flat-tappet
Ardun track cam like the one in #124 now. Cheers Bill
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