87 22r timing question for gas mileage

Hi
Is it more fuel efficient to advance the timing for a higher rpm or retard the timing?
Gas mileage has dropped since going from higher altitude living to sea level living.
Thanks
Mark

Theoretically, advancing the timing improves efficiency and gas mileage. I am under the impression that your vehicle's intial timing and timing profile are controlled by the ECM and not under your control.

You may know this, but it is the higher oxygen density at lower altitudes that caused your drop in mileage. The move to lower altitudes will also cause your engine to require higher octane gas than it did previously.

Thanks Brian
I will try advancing first. Hate to have higher RPM's while sitting at lights and stop signs but if it improves the gas mileage then that will be ok.
happy 4th

You're welcome. Shouldn't affect your RPM - also you may have no choice on the initial timing.