I just built a 383. I went to try it out. It started missing. Then popping. I reconized the popping sound. I tore off the vlave cover. I had two push rods hanging to the side. One rocker arm was hanging in the spring. The keepers where about to fall. I pulled the intake. I had one lifter broken. The peices were all in the bottom. The other one is coming apart. Its still togheter/ The retainer has it kinda jammed. Anyone ever ran into this. Just weak lifters I guess. Thats what I get for useing used ones.