1.7 roller tip over the valve tip
I have no intention of learning a whole lot about Oldsmobiles, but...
Are big block Chevy rockers compatible with Oldsmobile? Smokey Yunic developed a procedure for adapting BBC rocker arms to the SBC before high-ratio rockers became available.
When the ratio of a rocker is changed, the push rod cup is moved towards or away from the fulcrum center. It might also be moved up or down. The center-to-center distance between the fulcrum and the roller tip that pushes on the valve always remains the same for a specific engine.
Basically, as the ratio increases from, say 1.6:1 to 1.7:1, the push rod cup is moved closer to the fulcrum. If the design intent is to increase max-lift, the push rod cup is moved up as well as towards the fulcrum (decreases duration). If the design intent is to increase low-lift valve opening rate, the push rod cup is moved down as well as towards the fulcrum (increases duration).
If the roller is falling off of the valve stem, it sounds like the wrong rocker arm and/or push rod combination.
You might do a search for "mid lift rocker geometry".
Hope this helps OR maybe I totally misunderstood the intent of your thread.
Good luck,
Joe
