i removed the head from my 89 525 m20 and found a main cam journal scarred pretty bad (though this was not the reason for dissassembly and the car ran o.k. just had a tapping at 2k rpm and up) is there a cheaper fix for this journal other than head replacement? maybe a repair sleeve with a new cam? the head was installed used, ran fine for about 2 weeks, then started tapping. valve adjustment is good,no wear on cam lobes or rockers. suspect that this used head may have been shaved at one time. causing slight interference between valves and piston. installing thicker head gasket.