Re: Big block rods
Mark------
The 1969 L-88/ZL-1 rods were not the same forging as the 1970-71 LS-6 rods. Both rods used 7/16" bolts (although, as you mentioned, different bolts were used), both had the "dimples", and both were forged from 4340 steel. However, the forgings were completely different.
The L-88/ZL-1 rod was GM #3969804. It is the one with the ground shank boron steel bolts and it's the one machined for floating pins. It was discontinued from SERVICE a few years ago with a GM list price of about $200/each.
The LS-6 rod was GM #3963552. It had the knurled shank rod bolts and was machined for press fit pins. It was used for 1970-71 LS-6 engines used in Chevelles (1970) and Corvettes (1971). It was also the rod scheduled to be used for 1970 LS-7 engines. Although none were built for PRODUCTION, the engines were manufactured for SERVICE and used the GM #3963552 rod.
The GM #3963552 was discontinued from SERVICE in August 1986 and replaced by the GM #14096151. That rod was discontinued from SERVICE in March, 1992 and replaced by the GM #10198922 which remains available to this very day. All 3 of these rods have very similar beam profiles and other aspects of configuration. There were some modest improvements made with each design, but they're very difficult to discern with the eye. The GM #10198922 was also used for most PRODUCTION Mark VI engines.
Basically, the LS-6 rods have most of the strength of the L-88/ZL-1 rod but with a lower mass.
Mark------
The 1969 L-88/ZL-1 rods were not the same forging as the 1970-71 LS-6 rods. Both rods used 7/16" bolts (although, as you mentioned, different bolts were used), both had the "dimples", and both were forged from 4340 steel. However, the forgings were completely different.
The L-88/ZL-1 rod was GM #3969804. It is the one with the ground shank boron steel bolts and it's the one machined for floating pins. It was discontinued from SERVICE a few years ago with a GM list price of about $200/each.
The LS-6 rod was GM #3963552. It had the knurled shank rod bolts and was machined for press fit pins. It was used for 1970-71 LS-6 engines used in Chevelles (1970) and Corvettes (1971). It was also the rod scheduled to be used for 1970 LS-7 engines. Although none were built for PRODUCTION, the engines were manufactured for SERVICE and used the GM #3963552 rod.
The GM #3963552 was discontinued from SERVICE in August 1986 and replaced by the GM #14096151. That rod was discontinued from SERVICE in March, 1992 and replaced by the GM #10198922 which remains available to this very day. All 3 of these rods have very similar beam profiles and other aspects of configuration. There were some modest improvements made with each design, but they're very difficult to discern with the eye. The GM #10198922 was also used for most PRODUCTION Mark VI engines.
Basically, the LS-6 rods have most of the strength of the L-88/ZL-1 rod but with a lower mass.
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