Old 07-13-2019, 01:18 PM
charlie66's Avatar
charlie66 charlie66 is offline
Ultimate Warrior
Join Date: Dec 2004
Posts: 2,677

Originally Posted by tekuhn View Post
The reason you see a big visual difference is that the early rods through 1962 were forged and then the switch to cast in 1963 (except for a few high performance engines, of course). Early forged rods were no stronger than the later cast because they still Rockwell test quite soft, but they do tend to fail less catastrophically (stretch vs. break) so we used to run them before the aftermarket finally started producing a reasonably priced forged alternative.
Thanks for the pictures and the info.

I never seen a forged rod from back then before..

It looks strong...
Old 07-15-2019, 01:05 AM
Jack Gifford's Avatar
Jack Gifford Jack Gifford is offline
formerly 'Pontiac Jack'
Join Date: Dec 2004
Location: Phelps, NY 14532
Posts: 9,586

Originally Posted by charlie66 View Post
... It looks strong...
Looks can be deceiving. And it depends on how you define "strong". 1039/1040 alloy does have good yield and ultimate tensile strength. But when minimally heat-treated (these rods were only about Rc 16) their elastic modulus was very low. I never tested to get a number, but having the big end stationary and a dial indicator on the small end, it's easy to deflect it about .030" by merely pushing with your thumb!
Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons?
... or has built a DOHC hemi four cylinder Pontiac?

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