Sorry for putting it in the wrong forum, but I need to get an answer pretty quick. A friend of mine has a rebuilt 400 small-block in a 73 firbird. The oil pressure gauge reads 25 @ idle and 60 while cruising, but there is no oil getting to the rockers at idle, only when he revs it. What could cause this?

 

change oil filter brands seen that happen before

 

Ya don't have enough pump on it for the brg clearances.
The only reason ya got 60psi pressure at cruise is ya put a spring in the pump.
Thats what it sounds like to me.
Are there restrictor's going to the top end? Ya got a good filter on it? Is the distributor the right one and the bottom rings fit tight(rings around the shaft housing)? Were all the welsh plugs put back in the oil galleys? Are the 3 screw in plugs in the bell housing screwed in to far as to block the oil passages?
Just some things to check or think about. My money is a small volume/pressure pump with big brg clearances.