My 496 is 11.5:1.Canfields and I race with 93 octane :shock: No problems yet.Plugs look good and have seen a speckle.Motor never goes over 145 degrees water temp though.But my GMPP Fastburn (aluminum headed ZZ4,basically)in my Impala is only 9.5:1 and will not run on 91 octane without rattling,gotta use 93 in it.But it is also 4200 lbs with a 4-speed and 2.73 rear gears.Talk about a load taking off on a hill!!Especailly if my woman's with me :shock: Don't tell her I said that
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