No pinging on 91 or 93.
I had a vehicle I was trying to make run right and heard no pinging from it either 427" SBC..I tried all different timing curves.
Different carbs and different spacers and jetting, nothing worked well and even at low speeds and barely any throttle the engine just seemed to surge or act a little off.
Different spark plugs and wires and tried a new distributor cap.
Cranking pressure was 185 PSI on all holes checked with all spark plugs out.
Not knowing the compression and having exhausted all the tuning i cared to do I just figured this thing is getting some 112 octane and see what happens.
It was a different engine!!!
The thing was no longer surging or acting up at steady cruise at low speeds.
You could really tell this as it was a 5 speed stick shift car.
The throttle response was greatly improved and man the power increase it had.
We ran it around with that 5 gallons of fuel for 12 miles then added 4 gallons of 91 on top of that and it ran just as good.
Just needed more octane.
I had pulled timing to 28 total and even tried 38 total and you never heard it ping and did not make much difference how it drove..very odd duck for sure.
Never had an engine act like that.
I tried the same fuel in my V65 magna the 112 octane and turned it into a putz. It was actually quickest with 87 octane and went .2 quicker on 87 than it did on 91. compression was 10.5. You just never know.
You would not think octane would matter when you are steady cruising or just easing off the line with a stick shift.
But that 427" SBC would need a lot of clutch slipping to get it rolling without dying on the 91 octane.
The 112 made it drive like a new car.
If you have it available I would try it.. if nothing else it smells good