the shafts cannot be shimmed. the cam is a bullet with their springs 268/272@50-.712/.688 and spring #vs8100 with 245 on the seat and 595 open. i could set them up at 1.900, but than my pressures would be way to high. the easiest thing would be to clearance them. how much can be taken off without weakening them? i think .030" would do.