Fred, most of my experience is from circle track racing but through experimentation just a light deburr & streamline is the best approach; the counterweights are close to the crank centerline and it takes a heck of a lot of work in that area to see much gain. The flywheel having a much larger radius from crank centerline will gain more with less work; I use an automatic flex plate with a mini-clutch and a 6&3/4 or 8" dampner (230 or 250/292).I have literally spent hours on counterweights and find that controlling other chassis related variables gives more acceleration than spending hours polishing counterweights;the cranks seem to last longer also.Since the cranks are balanced without bob-weights any reduction in rod,pin and piston weight gives a gain in durability.Remember that other opinions may vary but generally that system worked best for me ...good luck
