The valve gear in my 1954 235 engine is so dirty I can't tell how it comes apart. (No oil filter.)

The problems is that there doesn't seem to be any oil flowing to the rockers for cylinders 2 through 5. I know I need to clean out the copper tubing that comes up from the pushrod area.

The question is: Is the rocker shaft hollow or does it just have small oil passageways, and how can I clean it out?


195? Chevy 3800 dump truck
1973 Chevy C30 cab and chassis
1987 Suburban 3/4 ton 6.2L Diesel