I went to pick up a pair of cylinder heads for a 92's 300ZX at a machine shop. there was a MB 6 cylinder aluminium head sitting on top of another bench. Just curious...I flip it over and noticed two of the EX valves'(#2, #5) surface have little dimples on them but the rest of them are still fine(those fine circular lines are still visible). Any idea what contribute that...bad injectors??
