You are right about having to lean and clean out the plugs. We had to do this back in the 60's, but we were useing 100 0ctane leaded. The Avgas now is 100LL (low lead).
To me, 100LL stands for 100 octane, Lotsa Lead (had wicked fouling problems in our club's '69 C-172)
Beach (Jim) WST / RI
