The rocker arm caps don't normally
need to come off, to get the stem
seals out you need to remove the cam,
loosten the rocker arm adjuster screws
first, pull the cam out from the distributor
drive side, now flip the rocker arms up
and out of the way, compress the valve
springs (can be a PITA) and get the keepers
out and get the valve spring and retainer
off and pull the seals, install carefully so
you don't damage the new ones, replace
the burned valves and reinstall the springs,
retainers and keepers.
Good Luck,
Wild