the stamped steels i've measured using a solid tappet, adjustable push rod, and checking valve spring were 1.5. all 1.5 adjustables i've measured, using the above mentioned method, were 1.6. all 1.6's i've measured were 1.65-1.66. going from a true 1.5 ratio to a true 1.6 will add about 5-7 degrees duration at .200 lobe lift, nearly nothing at .050 lobe lift; on the average flat tappet cam. and thats my story and i'm sticking to it.