I had a 3310-1 w/jet plate that I raced for many years. I had to drill the primary throttle plates to achive a good idle quality w/ a mild roller.I used a PV but didnt do any work to the PVCR. I did try some small wire to lean the idle curcit but finally pulled it and drilled the primary throttle plates. I think the hole size was about 1/8" but I'm not for sure.