I HAVE A PROBLEM ON MY 79 350 WITH A COMP CAMS 268 HI ENERGY SERIES CAM AND THE OTHER HI PERFORMANCE PARTS.  FIRST I HEARD A TICKIN FROM THE LIFTERS. SO I TRIED TO ADJUST THEM USING THE EOIC (EXHAUST OPEN INTAKE CLOSE) WAYH AND I JUST NOTICED WHEN I LET THE ROCKER ARM JUST REST AFTER I ADJUSTED IT, IT WAS EXCESSESIVLY LOSE. LIKE MY LIFTERS BOTTOMED OUT.  SO I REPLACED THNEM WITH COMP CAMS LIFTERS AND GOT THEM ADJUSTED WITH THE MOTOR RUNNING LATER THAT DAY WHEN I NOTICED MY OIL PRESSURE WAS AT 0 - 15 PSI AND THE LIFTERS WERE NOT PUMPING OIL UP THRU THE PUSHRODS WITH A VALVE COVER I CUT UP TOP. SO IM WONDERING WHAT THE PROBLEM IS?  I DIDNT HAVE A PROBLEM WITH THE OIL PRESSURE UNTIL I REPLACED THE DISTRIBUTOR WITH ANOTHER ONE EARLIER THAT MONTH. I WOULD JUST SHUT THE ENGINE OFF WHEN THE OIL PRESSURE WAS LOW AND TURNED IT ON AGAIN AND IT WENT UP TO 60 PSI. MAYBE ITS THE WATER IN THE OIL WHEN I TOOK MY INTAKE OFF. IM GOING TO CHANGE WHEN I FIX THE PROBLEM. ALSO THE MOTOR FEELS WEAKER AND I DO NOT THINK I OVER ADJUSTED THE VALVES. I WENT 1/2 TURN PAST ZERO LASH. WHAT SHOULD I DO

Check the distributor. Near the bottom of the housing is, if you will, a large groove, or should be. It is bounded by a circumferential boss at or very near the bottom of the housing and another boss a half inch or so higher up the housing. This "groove" is an oil passage. It must be there or no oil will flow to the lifters.

There are a couple other considerations; one, these bosses must make a reasonably tight fit in their mating hole with the block or a major oil leak will ensue causing a loss of system pressure. Second, the distributor itself must be mounted tightly, with a gasket, to the intake manifold.  If the distributor's mounting boss is proud (above this surface), the oil groove and bosses will either be aligned with the block oil transfer passage in such a way that a leak develops back to the pan. Or the boss blocks the transfer passage partially or completely cutting off oil to the lifters. Often this problem arises from the distributor not setting correctly on the oil pump drive. If the drive tang on the distributor does not drop into the oil pump's shaft slot, the distributor will sit high above the manifold, cutting off the transfer passage and very possibly not tuning the oil pump.

Bogie  

well i do have oil pressure until the motor warms up and in gear the oil pressure nearly drops to zero.  i  am usin shell rotella t diesel oil 15-40. i still have the old distributor. should i compare both since i have to take the intake of because of an oil leak. also, do the lifters affect oil pressure at all?? since i replaced the lifters with out changing the cam, do you think this will be a problem? the motor has not even been driven on the street  yet??

What condition is the bottom end in?

This sounds like the classic symptoms of a worn out bottom end where the clearance in the main and rod bearing has become too wide and the pump which has become weaker with age just can't put out enough volume to keep galley pressure up.

One can also envision other wear related problems as well. 

Bogie 

the motor has been rebuilt 3 months ago. aftermarket heads, flatop pistons. 9.5 compression. 218degrees @ .050 110 LSA camshaft (comp cams 12-210-2PN). im thinking the clearance in the bearings were built wide so im just going to use valvoline racing 20-50 oil. i sort of figured out how to turn the motor on to have oil pressure. i give it a quick hit on the throttle just when the motor turns on and the oil pressure climbs up to 60psi. i think the machine shop mensioned it was a high volume oil pump