"Scott" == Scott writes:

Scott Like I said, MIGHT OK, if there is no difference in
Scott heat, what are the 100 octane valves in my A-65 for? Or
Scott more generally, why do they sell 100 octane valves for
Scott A-65s and C-85s, etc. that were certified on 80 octane???
Scott Like I said, I use them, I don't wrench on 'em

I'm guessing--and this is just a guess--that their design differences
are solely to handle the considerable amount of lead still in 100
"low-lead" fuel. I use TCP in my C-90 to deal with the lead.
--
Happiness is an imaginary condition, formerly attributed by the living
to the dead, now usually attributed by adults to children, and by
children to adults.
~ Thomas Szasz