I've seen 42-44 degrees of timing on my stock automatic and I always thought it was a bit much. I always had some pinging and I think it was because of some carbon buildup because of the oil being pulled through the pcv. Even after tuning and headers I still get some ping so I think something else isn't quite right. But the car runs great with 45K miles so I'm leaving it as is for now. I think you're on track running some new 02's for baseline but give it a good Seafoam cleaning as well before the new O2's since it may damage them anyway.
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69 Z28 JL8 4 wheel disc brakes - being restored
09 Silverado Z71
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