W2 rocker arms.
Mopar made both types of castings that you see there. One style they did not drill the top hole when they bushed the rocker arm. The added another hole under the nose to oil the valve stem instead. Better oiling at high RPM for the valve tip - oil does not get flung off as it drips off the top and down the rocker arm nose. They drilled these on the top only when they were not bushed. The unbushed were called econo rockers. They were cheaper than the bushed to allow more people to afford the W2 set up.
Later they drilled all the rocker arms to facilitate production. When they press in the bushing it blocks the top oil hole. They add the additional hole under the nose to lube the rocker tip on the bushed rockers. See pictures.
I have owned all these types of rocker arms at some point.
See pictures of drilled intake rocker arm. No oil to the top through the bushing. Oil hole under the nose.
Mopar made both types of castings that you see there. One style they did not drill the top hole when they bushed the rocker arm. The added another hole under the nose to oil the valve stem instead. Better oiling at high RPM for the valve tip - oil does not get flung off as it drips off the top and down the rocker arm nose. They drilled these on the top only when they were not bushed. The unbushed were called econo rockers. They were cheaper than the bushed to allow more people to afford the W2 set up.
Later they drilled all the rocker arms to facilitate production. When they press in the bushing it blocks the top oil hole. They add the additional hole under the nose to lube the rocker tip on the bushed rockers. See pictures.
I have owned all these types of rocker arms at some point.
See pictures of drilled intake rocker arm. No oil to the top through the bushing. Oil hole under the nose.
