[Chevy454]

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Some of the really HP stuff like L-88/ZL-1 had cams that bled off so much compression at low RPM they would run on pump gas just fine if you didn't beat on them. Back in the day we ran the ZL-1 on 93 octane unleaded premium with no problem.

You would want to have a supply of fresh plugs and anti-seize around though.

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Those cams have such huge duration that cylinder pressure down low is nil...and when you figure that as built from the factory they'd be lucky to be 10.5:1 *actual* compression ratio, you can get by with a lot less octane than you'd think.