The motor is a 305 with about 155,000-160,000 miles on it. This mainly started after I had my exhaust system replaced from a 2 1/4 to 2 1/2 inch full dual system. But, when it started, it went away after warming up. Now, it is doing it constantly. There does not seem to be an exhaust leak, it seems further up near the head than where the exhaust starts. The engine makes a ticking/clacking noise while running mainly in drive when the rpms are down lower. But it will still do it while driving, just doesnt really do it as often when in park. I'm thinking it may be a sticky lifter, but I'm not sure. I have very limited valve train experience. But, if I'm able to tell the condition of the rocker arms when the engine is off, they dont seem very loose. A slight bit of play from side to side only, and I was told from someone at a parts store this is normal since if they are hydraulic lifters, that they arent applying the pressure they would on them while running.... If this is a sticky lifter, what is involved in changing the lifters. Can I take out the intake without taking out the distributor. Also, can the rocker arms be taken off without having to do anything to the valves? If I'm right, the keepers should hold the springs and valves in place while I remove the rocker arms, push rods and lifters right? I have included this link to a video while it is running with the passenger side valve cover removed: (It is about 10 MB, please give it a minute to load) http://logeeland.assumption.edu/~mporter/files/MOV00817.MPG Any help is greatly appreciated. I have been trying to determine what this noise is being cause by so I can finally drive it again. Thanks!