There used to also be two ways that octane was rated. I did not remember how it was calculated and I was the sub at the JVS yesterday and I asked the auto mechanics guy if he remember how they calculated that and he did not either. We decided for the one day show put the better stuff in. If is has a little carbon on the pistons it will ping. We had a gas demonstrator in 1961 and part of 62. When it was getting some decent hours on it we would put it on the dyno ans spray water through the intake as it was loaded to soften the carbon. That was one problem with the tractor, a lot of farmers did not have the quality fuel that was needed. By the way, In second gear that thing will pull all outdoors, in third gear they are short so you may want to look good with 5 bottoms. The dealer next door had a little lighter soil and sold a bunch of them with 5-14's cause in that neighborhood it would pull that combination in third.
Other than that how you doing? John