It is a broad misconception that octane produces more power. I have had drivers talk to me while I was off loading fuel, and you would be amazed at the things people would say or ask. Many think premium is like the difference between beer and champagne. As a kid, I once tried running my '70 442 on high octane aviation gas. It ran really bad. I run my boat in the Raritan bay/ Hudson river area. Very often a day is spent anchored somewhere to swim and party. Twice a season I make a 55 mile trip up the Hudson river to West Point NY. My tank holds 125 Gals and I can make it round trip without refueling. This will be my first summer running the 502. It's probably best I don't take any chances with 87. At least for now. The block designation is ZZ 502. The cam is a roller. 224-234 duration with an LSA of 110. I have an 800 holly spread bore, and eventually I'd like to switch over throttle body injection. I imagine that would have to include a computer management system.

i have found that burning fuel with a higher than needed octane rating will make a little less power but in your case not knowing your afr i would run the higher octane fuel.you can spend a little more for the fuel or a lot more money replacing fried pistons.jmo.

^^^^ that's the long and the short of it...

I remember Eddie Young explaining octane ratings and engine tuning during the assembly of an engine he built for me. I'm not an engine expert like a lot of those that have already responded. However Eddie dumbed down his explanation for me so I could I understand the basics. He said an engine is setup and tuned to run on a certain octane rating. If you run an octane rating too low or high for your specific engine it's not good. An octane rating is just how volatile the fuel is under compression. The lower the rating the quicker it will ignite when compressed.