Sorry to see that!
When the crown eats away on the exhaust side like that, its from excessive heat from too lean of jetting, poor fuel, air leak, ignition too far advanced.
In this case[because more then one piston is involved] I would suggest its probably from too lean of jetting combined with todays fuel.
Hopefully you caught it early enough that it has not damaged the cylinders.
What main jets, needle postion, pilots was this sled running?
Gutted Airbox?
Cold air kit?
Ignition advance key?
Heads cut?
Premium fuel?
When the crown eats away on the exhaust side like that, its from excessive heat from too lean of jetting, poor fuel, air leak, ignition too far advanced.
In this case[because more then one piston is involved] I would suggest its probably from too lean of jetting combined with todays fuel.
Hopefully you caught it early enough that it has not damaged the cylinders.
What main jets, needle postion, pilots was this sled running?
Gutted Airbox?
Cold air kit?
Ignition advance key?
Heads cut?
Premium fuel?