when he said regular pump gas, I thought he said (and meant) regular (87 octane) pump gas.
I could not run the "Regular" grade of pump gas ( 89 octane or so) back in those days (had to buy the 22 cent stuff). Those old sixes with their Recardo(sic) designed combustion chambers were very octane hungry motors, some said they were a copy of an older Mercedes chamber-never researched it though. Never seen another combustion chamber like them before or since-the high comp pistons were really different too (the flattops with a piece of dog poop on them).
Filling station attendants would grin when I asked for a couple of dollars of ethyl for my smooth idling '54 chevy. But it would rattle like a sack of marbles hitting the fan if I didnt.
That old 261's ratio with the '54 235 7.5 to one ratio head actually had less than 8.75, maybe closer to 8.5. Heck the '57 and laters were up to maybe 8.25 and burned low octane, with stock distributor timing. But when you bumped the timing up you wouldnt go back to stock settings.
So maybe it was the higher timing, rather than the compression ratio, but I would not give back the additional snap and response of the advanced timing for the sake of a nickle per gallon difference in price.
