10 degrees BTDC is a good starting point, but depending on the grade of fuel you run, it may like more or less timing. You want to advance it as far as possible (BTDC) till it starts to ping. Then back it down a couple degrees ( toward ATDC) Generally,the higher octane fuel you use, the more you can advance it and the more power it'll make. But some engines have compression ratios so low that using higher octane fuel is pointless, no matter how far advanced you set the timing at.