I run the higher grade fuel only because of the non-ethanol component to it. That is the only octane available in non-ethanol at the local gas station. Yes adjusting the idle mixture screw does change the RPM. Wondering if my float is too high or main jet too large. I will try advancing the timing a few degrees and see what it does then.
Matt,
I use ethanol 87 octane in every one of my vehicles except those with high compression engines like the Cadillac and the Toronado. It works just fine. Your engine (and mine) has a compression ratio akin to a Briggs & Stratton lawn mower. I've never suffered an ethanol related fuel problem in any of my vehicles. That being said, I drive my cars all the time and gas doesn't get a chance to go bad.
You might not be aware that pure ethanol has a higher octane rating than pure gasoline and is used to boost the octane rating on premium fuels. It isn't 10% so it isn't labeled as such.
Anyway, my truck had a FrankenCarter (various year Jeep spec parts) on it when it came to me and it ran pretty good until it didn't. I purchased a rebuildable Carter core and it has run flawlessly ever since. The money spent today on a proper carburetor now is long forgotten when you're driving down the road without any fuel problems. Close to 7000 miles in the last two years. I even commute in rush hour traffic and the truck runs like a noisy sewing machine.
