I just traded for this car,it has a 73 340 with a hydraulic cam. When the car arrived and i started it it sounded like it was not pumping oil to the lifters. I went right away and put an oil pressure gauge on it. It has around 20lbs at idle and goes up to 40 with some throttle. I thought the lifters may be bad so i just installed a new set. And it is going the same thing. With the valve covers off it is shooting what seems to be plenty of oil in the rockers. The rockers do seem awful loose on the shaft, could they maybe be worn out and not letting the lifters pump up ? Thanks for any help here.