273 Rocker on 340

I ran them on race cars 50 years ago with up to 550/570 Lift.
They clear 1.47 spring with no grinding. Do not get crazy on the
grinder as they tend to crack pretty easy around oil hole.

Another issue is that the interference adjuster tended to loosen every
10/20 runs. I spot faced the rockers and put a nut style adjusted on them.

There are better cast rockers on the market now.

Watch them closely for excessive wear.