ClassicCar

While you are at it, I would suggest checking the rocker arms and shaft. It is common for sludge and gum formation in the rocker arms and shafts which will restrict the normal flow of oil to the rocker arm and shaft assemblies that may ruin rockers and shaft.

After disasembling the rocker shaft assembly, keep every part in the same order, as was on the shaft, so every part goes back together correctly in the original locations. Clean all sludge and gum formation from the inside and outside of the shafts and from the oil distributor to valve rocker shaft tube. Clean all oil holes and passages in the shafts and rocker arms. And clean the rocker arm shaft oil connector assembly. Inspect the shaft for wear. Worn rocker arms and shafts should be replaced.

Good luck
Lee O'Dell