Review Details

BSA A65 A70 Black Diamond Oversized Intake Valve 1.659"

Product Review (submitted on August 21, 2017):

These valves are nice. I had reservations about the swirl pattern finish so polished it off when I was trying to get flow out of the port I was modifying.
However after getting a small 32mm oval port to 155CFM @ 28"W @ .350" lift, (according to my bench) I thought I'd put the other 'as it came' valve in to see the difference. I figured the less smooth texture would reduce flow. But to my surprise the result was 158CFM @ .398" lift. The port shape makes a huge difference in these heads but a badly shaped valve can kill it. These valves are great.