knocking sound coming from intake

i have a knocking sound from the inake not sure the prblem is i have a untouched block with afr 165,1.6 rockers,xe266hr cam trickflow street intake everything is new i'm thinking pushrod lenght is not right i have stock lenght in.is anybody using this setup and what lenght pushrods are you using.i can spin the pushrod but they seem to spin way to easy.

knocking

no it's not popping or anything like that i can hear tapping from the valve covers but it sounds like it coming more from the intake maybe the sound is travling from the valve cover but sounds like it's coming from the intake.it does not get any louder when i rev it stays the same