I have a set of 1.5 and 1.6 rockers for a SBC I'm assembling. The 1.5 are Comp steel the 1.6 are Harland Sharpe aluminum. I'm using the marker on the valve tip method and finding the 1.6's need .100 longer to obtain the same pattern. Is this common, just seemed like more than I thought it would.
As I said I'm using a marker on the valve tip, Comp adjustable pushrod and checker springs. Head is installed with gasket as I was checking V to P clearance.

First it doesn't matter what's common, you need what you need to get the correct geometry. With that said I'd bet the different manufacturers are likely the main reason. With the same manufacturer and rocker type I'd expect the 1.5 rocker to need a longer PR.

The pushrod cup or seat in the rocker just moves over to get the higher ratio on many stud type rockers.

2 different brands could easily be a bit different dimensionally causing a pushrod length change to be needed

Whatever pushrod length that gets you in the center of the valve or as close to that as possible is what you need.

quote:

Whatever pushrod length that gets you in the center of the valve or as close to that as possible is what you need.

That's an interesting point. I've read and watched videos. The marker and getting the pattern in the center is the popular method. But many say the tighter the pattern the better even if it's not centered. Then there's the 90* at midlift method.