318 head cleaning question

Alright so as some of you may have seen, the heads off of my 318 definitely need a good cleaning. Ive been told to use either diesel or degreaser to break the sludge down, i have both. Afterwords i was going to pressure wash the heads. This may be a stupid question (first time engine rebuild here) but would it hurt the rockers/ valve springs and such if i was to pressure wash the head with them in? Thanks