Small ticking

i own a stock 79 camaro with a small block chev 350. i was tinkering under the hood one day and heard the slightest tick. can barely even hear it unless I was listening for it. when i hit the throttle the tick spend up. i took the valve covers off and reset all the valves and the sound seemed to be gone then i put the covers back on an had the tickin noise back. oh yeah the valve covers are a edelbrock chrome dress kit. Could the rocker arm just be brushing something inside the cover???Also when i baught the car it came with a rebuilt 400. which my dad took because this was my first car and he didnt like the fact i would be able to put the car sideways with ease, and he has a 55 chev so he really wanted a bigger engine then a 350. anyways the engine has a big knock on the passanger side 3 from the front of the engine. it isn't too high compression and not the timing chain. We checked everything we could without taking the heads off. Any ideas??any help would be much appreciated