its 101 octane on our scale ,its only got low lead directly compared to its bigger brother- another aviation blend with 115 (dont use that ) 100ll actually has a good amount of lead in it compared to other race gas products plus it has oxygen additives which is like free horsepower ,some airports sell it for under 3 bucks a gallon you may need to bump up the main a size or two for the extra oxygenation,porcelein should be about the color of a cardboard box and strap should be burnt back alittle over half way , tip of electrode should have a little ring of discoloration on it less than one millimeter ,thats where you figure out your ignition timing also id run +8 degrees on straight 100LL if it was me,av gas burns clean and dry so be sure to use 32-1 ratio for extra protection klotz supertechnaplte works and mixes well with it ,the blasters lowend torque and throttle response should pickup a good deal on 100LL over premium pump if its tuned right