Octane Question

It says that my 390 S-Code needs 98 octane??????


Will Chevron 91 be ok, or will i have to make some kind of brew for my Fairlane???


Thanks,

Ed
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91 octane is the highest we can get at the pump here in Kaliphornya. If you're just cruising it without "getting on it" all the time, the 91 will be fine, but if you are excited about that right pedal (who is'nt??), then add a can of "108" octane booster with every fill up.

Thanks,
[addsig]

that octane number in the owner's manual reflects the way that they measured octane in the 60's, which is known as the "research" number. nowadays, they use the "(R+M)/2" method, or the average of the research and motor octane. on 91 octane of today's gas, the high number is probably around 100 and the motor number is around 80, therefore an advertised octane of around 91. depending on your engines true compression, and you timing, you could run 91 pump gas. a 10.5:1 engine is about all you can run in 93 octane that we have here in NY. you can retard the timing to run on pump 87 octane, but your performance will suffer. the other issue is that the gas of the 60's had lead in it, which doesn't do your valve seats any good. you can put lead substitute in the gas every other tankful, or not worry about it like me. it would take 30,000 miles to affect the valve seat worth worrying about... (that's just my opinion, though)

Thanks Scott..........................
[addsig]