are your heads aluminum? I and some Chebby friends seem to agree that with aluminum heads and rockers and add aluminum covers too that the engine noises are louder than normal. Hughes told me on assembly to put a piece of masking tape on the push rod and rotate it. If it tears the tape it needs more clearance, if it just leaves a rub mark it's acceptable. With the extreme angle of the push rod with the retro hyd roller lifter, my push rod moved away from the tube and came in contact again during the cycle. my observations. I dont know whether my lifter noise is the push rods or the notoriously noisy retro lifters. but its not terrible like the video.
