Do I need to run a different gas?
The valves are stock and the cam is stock
Valve springs are 18lbs
I'd hit google up and see what you find. I'm sure there is some good info out there. I'm not an expert, and I can guarantee there are some guys on here that know there stuff. Hopefully they'll correct what I get wrong, and they'll share their knowledge with you.
High compression engines can cause the fuel to ignite prematurely. Alky has a lower ignition temperature, and it runs cooler too. That's why engines designed for racing use higher octane fuels or alky. You want your spark plug to ignite the fuel, not the compression of the fuel and air. You want the fuel to ignite at the top of your stroke to maximize the power (although some do play with their timing a bit). If your fuel/air mixture is igniting to prematurely, you're going to be fighting to get the piston back to the top. It's kinda like trying to push the pedal of your bike down before it is back to the top in a fixed gear application (ie. no coaster brakes and no freestyle bikes).
Diesel engines don't use spark plugs. I didn't know that until a year or two ago. The diesel fuel is less refined, and I think it ignites with just the glow plugs and compression. I don't totally understand the science behind it, but I'd love to learn. I've never owned one or torn one apart.
I think most cars run around 8:1 compression. Some are less, I'm sure. As you run the motor, friction destroys the rings and cylinder wall, which in turn lowers the compression ratio. This means you'll lose some compression as you run your engine too. Most racing engine builders "freshen up" their motors often. High RPMs kill motors if you don't care for them and set them up properly.
Like I said, there are some really smart, experienced guys on this site, and I recommend listening to them. Experience with this stuff is valuable. One conversation with someone who knows there stuff is worth more than a weeks worth of research on the web. I'm hoping someone will chime in and explain this better (and more accurately) than me. Be polite and humble if you are given the chance to sit down and learn from them. You'll not regret it if you do.