I have a new set of Mazdaspeed cams that I want to drop into my motor, but I need to find a source for the valve adjustment discs slightly thicker than Mazda offers. The thickest shim from Mazda is 3.75mm and I need to get maybe closer to 3.85mm in thickness. I've tried lash caps on the valves that have the lobes with extra clearance, but then if I use the lash caps and the thinnest shims I have zero clearance. I realize how critical it is to obtain the proper lash with our motors, so I was hoping one of you might have a solution to my problem.

 

being off .1mm isn't going to make any difference and it won't tap or make noise. Get as close as you can and be done with it..... OEM does no better.