wierd engine sounds

[chicogixr]

im getting wierd engine sounds coming from what sounds like the pass. side. it sounds like detonation but its louder and it doesnt happen all the time. it happens when its its accelerating any faster than your grandma does, but when the engine is been running for like 15 minutes it doesnt do it- only a little sometimes. performance is the same so i dont think its a connecting rod. maybe one of my rockers is a little loose? i think it might be the torque converter or flywheel but i dont see any rub marks. since it stops after a while maybe something with the transmission?how fast to atf heat up? ill try to pull the valve cover tomorrow but for now i dont know. its a newer engine maybe 10-15k 350. in a 79 k10 and a t350.