I`ve got late model roller cam block. It has comp xe 292,doug hebert hydr. roller lifters, new built engine. When cold the lifters are weak,you can push with hands. It backfires out headers when cold,and quits when warm. Lifters got to be bad. Anybody had trouble with this brand?

How much preload did you put on the lifters? My Comp instructions say .002-.0004. Maybe try minimal preload.

I think you have them waaay too tight. You could be backfifing because the valve is hanging open once pressurized. How did you set them up? You can't set them up like a solid. The plunger is supposed to collapse a when they have no pressurized oil in them. Once the oil pressure comes up, it forces the plunger piston up and the slack is taken up. You set them by tightening down a predetermined amount when they are running. Cold, I put the lifter on the base circle ( Intake opening, adjust exh. Exh opening, adj intake). I tighten down to take the slack out of the rocker. I put 1/2 turn extra. Do the whole set of 16, start engine. Once pressurized, I back off the rocker untill it makes some noise, tighten down untill it is quiet, then go 1/2 turn more to press the plunger down into the lifter body. I've done it this way on hydraulic std and rollers and never touch them again.