Look at this post, do some WOT runs all the way up to redline (and going over 5500-6000 isn't worth it.) The following is based on 91-92 octane oxygenated fuel. You may do better.
You will likely see KR in the 3000-4500 range. It's not uncommon to see nothing above or below that.
2 degrees is fine. 4 is Ok. Above 4 you will start feeling surging in the power. Beyond 6 you need to make some choices to get below 4 (or even down to 2).
1. Get cooler air from somewhere.
2. Reduce the advance in the right column of the spark table to get it under 4 degrees KR in the affected area.
3. Increase the octane of the gas (and octane boosters that come in a bottle don't work).
4. Add an intercooler.
5. Add water or water/alchy injection. Aquamist comes to mind.
Don't be surprised if you see knock all the way up to redline but 3800 have peak in the 4000 RPM range.
If you are seeing more than 8, you have to figure out what is going on. It could be false knock from something hitting in the cradle, loose KS up to real live knock (bad juju).
Of course, if you are lucky and don't have any knock, you can consider maybe even bump the advance up some.
TK
