Pm rods
Moderator
Joined: Dec 1969
Posts: 10,745
From: Buffalo, New York
Originally posted by WS6 TA
Hum… interesting… I did some digging through my library early this morning.
I couldn’t find any mention of castings and all the traditional SBC rod pics that I could find were clearly forgings (wide parting lines…), but I did find out that they were forged from 1038 (not really what I would call the strongest material), and that in ’89 GM went from their traditional .570-.575” beam width to roughly a .505” beam width in all their small blocks, including the LT1’s till ’94. Funny that it weighted the same or slightly more then the old wider rods since they moved the weight over to the balance pads. That made it one of the weakest factory rods and apparently the ’92-95 LT1’s were the only modern SBC that had any significant occurrence of rod failure in stock engines.
You learn something new every day, in this case:
- PM rods are probably stronger in most applications then the old “pink” rods, which were just cleaned up and magnafluxed production forgings
- As far as I can tell, all factory SBC rods are 1038 forgings, the goodwrench race ones are 4140 forgings but too heavy to consider for anything
- Stay away from the ’89-94 rods at all costs, they’re just crap.
Hum… interesting… I did some digging through my library early this morning.
I couldn’t find any mention of castings and all the traditional SBC rod pics that I could find were clearly forgings (wide parting lines…), but I did find out that they were forged from 1038 (not really what I would call the strongest material), and that in ’89 GM went from their traditional .570-.575” beam width to roughly a .505” beam width in all their small blocks, including the LT1’s till ’94. Funny that it weighted the same or slightly more then the old wider rods since they moved the weight over to the balance pads. That made it one of the weakest factory rods and apparently the ’92-95 LT1’s were the only modern SBC that had any significant occurrence of rod failure in stock engines.
You learn something new every day, in this case:
- PM rods are probably stronger in most applications then the old “pink” rods, which were just cleaned up and magnafluxed production forgings
- As far as I can tell, all factory SBC rods are 1038 forgings, the goodwrench race ones are 4140 forgings but too heavy to consider for anything
- Stay away from the ’89-94 rods at all costs, they’re just crap.
Rich Krause
Registered User
Joined: Jul 2000
Posts: 520
From: MD
Yea, I don't think I was suggesting that they are the best choice for most of the builtups done by people here, but I can definitly tell you what rods I will not be sing if I build a new engine for my daily beater/truck...
Registered User
Joined: May 2000
Posts: 799
From: Redmond, WA
FWIW, Chevrolet usually does things for a reason, and in most cases, it's to save a buck. PM rods are cheaper to manufacture, as far as I know, and while they probably are stronger than the old "pink" rods, that's not saying much with the advances in materials and technology in the last 20 years. Sort of a red herring, if you ask me... their attempt to make you think you got better rods while they saved $0.20 per unit or something. 
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