340 Pinging using 94

Carboned up combustion chamber can cause pinging, two reasons:

- piece of hot carbon pre-ignites the mixture
- it increases the comp ratio.

Anything that cools the engine temp also reduces the chances of pinging. Too much anti freeze when it is not needed for THAT climate reduces the water's heat transfer capability.
Relying on the temp gauge can be pretty useless for pinging problems. It only tells you what the coolant temp is at the sender; the coolant might be 20* hotter around the exh valves, where there might be a hot spot.