no oil on rocker's drivers side only? 360 magnum

yes the oil holes on the lifters are facing the center of the engine. I checked that when I replaced them, the first set about half of them were 180 off... yes the lifters or valvetrain are noisy, and it is coming from the drivers side of the block. I got the engine used and as far as i know there wasn't anything done to the block before. I have 20w50 oil in there, would changing it to a lighter wieghter oil be worth trying to do?. the passenger side is getting oil up top.