Is anchorage marina's 100ll av gas? and what changes do i have to make when switching from pump gas ? like timing, jeting? bbc, alu head, roots 9psi Thanks Dip

only av gas uses the 100ll designation.... will be extremely light almost transparent blue if it is. if it is it will work as a direct replacement for 87 or 92 just fine. the flame progation will be a bit slower because it burns a bit slower and is a fine fuel for those razor edge 9.7 or 10 to 1 motors. only downside will be if you are running efi w/ an o2 sensor which it will kill in short order.

its not going to make you any more power as it is not an oxygen bearing fuel but it will keep you safe and if you cared to dyno and jet for it you could certainly get at least what you have now. no rule of thumb for jet sizes unless you knew the density of the fuel you are jetted for now vs the air density on the day it was jetted and then BELIEVED that you had the number correct to start with...

short of that , any change you make will be pure guesswork...which i suppose if you went really slowly and checked performance vs plug color or exhaust temps, you can get away with...

for me..if the boat ran good now and you felt you needed the extra protection, ide put it in and run it as is w/out a second thought.