I had to do this with some 273 rockers - be sure that when you tighten that lock nut on the surface of the rocker that it has been machined true and level. You'll have to take the rockers to a machinist and have them machine down the casting surface into a level surface perpendicular to the adjuster. Some of those 273 rockers with the interference fit adjusters do not have this area machined and it's just bare casting.