So, finally, an update:
1. Pulled the radiator and had it boiled again.
2. Attempted to install a spacer between the fan blade and pump but the fan would've hit the top tank on radiator - so that was a no go.
3. Added a bypass hose from rear of head to water pump, just because I could. No heater to help dissipate any of the excess heat.
4. Replaced the water pump even though the unit that was in it is only 2 years old.
5. Replaced 165 thermostat with new one. The replaced unit was only 2 years old and after I pulled it, tested it and it started opening at around 150ish, so that wasn't the issue.
No difference in symptoms. Runs at around 180 under speeds of 45, or so. Then if approaching a hill of any length, the temp would quickly bounce to around 190 - 195 and start pinging (and losing power). Letting off or cresting the hill would result in the temp dropping almost immediately.
All that is to say I made no progress. Time for something completely different.
Because timing, fuel, etc. can all impact ping, and knowing I could not retard timing any more than already set, as I could sense a decrease in power. So, the other option I'd not previously considered is the effect of increasing octane, as its effect is to retard the detonation of fuel. The question became whether to increase from a rating of 84 (with Ethanol) to 87 (with Ethanol) vs. 91 without Ethanol. Filled the tank with 91 to also rule out the ethanol and glad to report I cannot get it to ping. Temps still climb to nearly 200 while hitting hills, but no ping. So, as long as I can keep it from overheating, 91 octane is in my CJ's future.
For now, that's where I am.
