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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
I didn't read all of the posts, but I want to say and show this. These rockers had 9,400 miles on them when I removed them spring of 2016. It is pretty easy to see the offset puts a twist on the rocker. I went with Crower Shaft Rockers. I believe these are not as easy to side load the smaller trunnion bearings.
Street driven, just rolled over 38,000, heads were done in 2016.
Do you know if the intake guide clearances were out of spec (.0037")? If they were, then the intake valves were seeing fatigue and are subject to increased risk of failure and likely to create more rapid wear in the new guides. 2006-early 2008 LS7s were most likely to have the exhaust valves fail as there was uneven wall thickness around the sodium cavity. Some time in mid-2008 MY, Chevy made a change (same PN but either different supplier or improved QA by the supplier) and thereafter a higher % of intake valves failed. Throughout the entire LS6 production, Linimar had manufacturing problems with valve guides being out of spec re concentricity with the valve seats.
Different supplier, and, AFAIK, new supplier was Mahle. Can't remember the original supplier. I do know that GM approached Ferrea about supplying the original spec valves. They refused to manufacture the sodium filled exhaust valves, saying that the GM spec exhaust valves couldn't be manufactured to their standards using such a thin wall. Good on Ferrea for not compromising their reputation by building something they knew wouldn't hold up, and it turned out that they were correct.
Last edited by grinder11; May 28, 2026 at 06:28 PM.
