273 Mystery Motor

#1 pop a valve cover and see what's cooking under there. you'll know right away whether it's hyrdo or adjustable (are there adjustable rockers; if there are, a push test should tell you if the lifters are solid or not).

#2 scope the bore and check the pistons.

#3 why'd you take it in for a valve adjustment? was it running poorly or were you just getting ahead of it with some PM?

it's mighty coincidental that you just happen to have a cam go flat after a visit to a shop.