So you read the book "How to Modify Your Datsun...." and decided to lighten your rocker arms for performance?
You may not wish to bother.
I just did a quick check.
Mass before grinding:
78.25g
Mass after aggressive grinding: 74.58g
Weight Saving: 3.67g ( ~ 4.7%)
When you put this into perspective: Crane retainers are 31.368g compared to Nissan 23.444g retainers so if you use Crane retainers, you are already off to a bad start.
Grinding can help but I think it is only useful for true racers who need to baby their cams and springs which are pushed to very high lift and rpms .
Crude Calculation:
mass: 0.004 kg
travel: 0.011 m (lift)
frequency: 6000rpm = 5Hz at Cam
average velocity: 0.11m/s
momentum = 0.00044kg-m-s = 0.0032ft-lbs-s =(0.038ft-lbs-s for 12 rockers)
hp = 0.004
