Ignition timing ?????

[SS 454]

Hey guys ! I have a 1991 Firebird w/ the 3.1 six cylinder engine.
When I bought it the hood had been replaced after a minor accident. Thus no sticker with the specs. It is now set @ 4 degrees BTDC and seems to run well, after a good major tune up.
However, the Chilton manual I have lists my motor and all the previous 3.1 and 2.8's @ 10 degrees BTDC. Also am I wasting my money by using premium gas. Thanks for any replies.

[Rob B (shoebox)]

Use the lowest octane gas that does not ping.

[fastTa]

There shouldn't be a problem with advancing the additional 6 degrees as per the Chilton Manual. But it never hurts to call an experienced mechanic to get a different perspective. The additional 6 degrees should improve your performance and could likely increase gas mileage.

My words to follow will without fail conjure a "friendly debate"

Unless you are experiencing knock, there is absolutely no reason to use 93 or even 91 octane for that matter (plus and supreme here in TX). You will not get better gas mileage, you will not clean your fuel system better, and you will not make more horsepower with higher grade gasolines. All the major petroleum co.'s provide all grades of gasoline with equal amounts of fuel treatment.

A higher octane rating essentially means it takes more effort to combust the fuel. This CAN be beneficial when you are running a high compression motor or have quite a bit of timing.

Just my humble opinion.

[CLWILSON]

When I first got my 3.1 the timing was set at about 6 BTDC and it ran well. When I was going to have it smogged I set it at the stock setting of 10 BTDC and noticed increased performance and gas milage. It also seems to idle smoother.

[SS 454]

Thanks for the replies. I had intended to go for the middle grade gas and set the timing up since i noticed the tailpipe had a carbon accumination on it. Will let you know how it goes.