I will take a stab at it, if no one else has answered. Many different factors go into the decision. The thing you are trying to stop is "pinging". Ping is cause by the mixture igniting at the wrong time. Be it from carbon in the chamber or from hot side walls or whatever. In the cooler months, you may get away with lower octane. Also engine internal parts have something to do with it. My D-shaped dome pistons help to reduce the pinging but some high Compression engines will not stand less octane because the compression itself will ignite the mix and cause it. Try several remedial steps and find out what your motor likes and that will be the best you can do. mike
--- Brad Olson <[EMAIL PROTECTED]> wrote: > -------------- Original message > ---------------------- > From: "John Nasta" <[EMAIL PROTECTED]> > > I am looking at a 9.1:1 350 for my Malibu and am > wondering if that would > > require mid-grade or even premium to run nicely. > Any guesstimates as to what > > You can always retard ignition timing to somewhat > overcome an > octane deficiency but chamber design and cam specs > are also > factors. What heads and cam does this engine have, > and what're > the cam installation specs? > > Brad > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
