While having a recent conversation about engine components, an interesting question arose about true rockerarm strength and deflection. In this case it had to do with the old Isky iron and MP aluminum units. Since I personally have never placed any real serious load on them (over 350#) we were wondering how much 'actual load' (not theorectical/wishful or imaginary tension) but actual spring load over the nose and through the cam ramp cycle these rockers would 'safely/effectively' take in race-type environment? It is a curiosity...

That's a tough call as the thoughtful racer will use lightweight valves, retainers, and springs(within reason) to achieve better valve control throughout the working RPM range.

Of course there are limits - where deflection becomes unacceptable - but without some fairly sophisticated measuring tools these limits are difficult to discern. A few hours of spintron work should provide all kinds of useful data regarding deflection under various spring force scenarios.

Several of us used the original MaxWedge and Isky rockers on our SS cars back in the 70’s.

We used the Direct Connection Triple and Battleship springs without any rocker arm failures.
If I recall correctly open pressures were close to 500.
Trick Titanium retainers and hard DC locks.

We only spun the motors around 6700-6800.