its diferent on every motor, but I generally try to make sure the tip moves to the same amount either side of centre, and generally this means that at approx. half lift it should be in the centre of the valve tip, but it also depends where they sit, you need to draw a line from the tip of the valve through the centre of the pivot point, if its flat your gonna want the rocker to be lower, it should be pretty close to 90degrees to the valve stem at half lift..
so will be something like at seat it will be towards the outside of the motor, as you open the valve it will move towards the centre and across towards the inside of the motor ....
if it goes right to one edge of the valve tip too much that's no good.
oh and be careful with them pedestals, if you have the rocker too far one way the bottom of the cut out will hit!
what length pushrod do you need, im sure precision has an absolute shite load of options available ?
heres an example, ideally you want to get it so the rocker is lower at the pushrod, and the line through the pivot to the tip is slightly up, half lift 90 degrees to stem, then full lift slightly down.
this is when I was fitting VN V6 rockers to a holden 6, I ended up needing a 308 + .010 length pushrod which was a standard available option, but its not always that easy lol!
vn-v6-rocker-onhead-end.jpg
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