What brand are the lifters ? There have been alot of problems with the Comp lifters. Apparently they do not do a good job of de-magnetizing the bodies after maching them and it causes the valve inside to stick to the bottom and not allow enough oil to get inside.The cure for this is to remove the lifters from the engine and take them to a machine shop that can de-mag them for you,any shop that has a machine for magging cranks can do this.If it is a Crane they recommend .090 preload ,which is about 1 1/2 turns,it should have stated that in the instructions.