My stock push rod is 7 3/16" long. I'm changing to 1.6 rockers on an aftermarket aluminum head. I'm trying to choose a length range on the test rod. How much do you generally add with a change like that? I assume we're talking in the thousandths, not inches. Would I be safe to get a Rod that's 6.8 to 7.5 inches?

 

How are you checking? If your doing the sharpie sweep method, make sure to use lightweight test springs. The comp test springs are too narrow for most seals, I just got some from my local hardware store.

With all my SBC projects cars(5) I just got the Comp Cams Hi-tech pushrod tools, need both since it > 7.8 & < 7.8 for flat tappet but sounds like your roller so the shorter one would be fine.