"Kruse" > wrote in message
ups.com...
>
> goodnigh wrote:
>> I understand that what octane meant in 1971 no longer applies.
>> Just received a set of owner's manuals purchased on eBay for
>> my 1971 Mustang. The book says I need 99.8 octane.
>> Where do I buy that? Do I need to go to a local hardware store
>> and buy some toluene to pour in the tank?
>
> Not sure exactly what engine you got in your Mustang or how well it's
> built, but I've got a '71 Cougar (351C) that I put a few hundred miles
> on per year. I will run on 91 octane with no problem but if I'm going
> to get on it a little bit, 93 can be used. If you need higher octane,
> which I doubt, you can mix some racing gas with it and blend it until
> you find your best mix.
>
> If it ran good with pump gas before you got your manuals from ebay,
> why would that change now?

What I am getting from this thread is, if the engine runs without pinging at
89 octane, using 91 octane will not improve performance. If the car
pings with 91 octane, tuning the engine to run on 91 octane will likely
improve performance. The engine is a 351C 4V, but with the Edelbrock
parts, it is not stock.

mike