I have heard that doing a 4.0 head conversion on a 4.2 block will eliminate any pinging.


78 CJ7, 83 wide track axles/Dana 30 Front W/ OX Locker, Model 20 rear w/ one piece shafts(welded tubes)/Detroit Locker, 4.10 gears. 4.5" spring lift with 3/4" shackle lift. 35x12.50 BFG MT, 4.2L, Weber Carb, K&N, T18,Scout Dana 300,Warn 9.5ti