I have a Spectra 20 460 with RPM manifold, edelbrock 750, logs, DUI HEI. Went out the other day, fired it up at the ramp, didn't notice anything wrong. Putted out, put it on plane, ran that way for about 1/4 mile, hammered it for a few seconds, brought it down to idle for a no wake zone and a faint ticking can be heard. Threw out the anchor and started searching. Checked oil level and it was just above add line. Put in a quart with no change in the noise. Pulled alt belt/ still there, pulled valve covers, all rockers are oiled and snug and lifters are tight, not able to push them in. Drove the boat back to the ramp, on plane, for about a mile and it seemed louder. Next day did some more troubleshooting on the trailer. Removed bell housing plate and could hear the noise but not coming from this area. Pulled the spark plugs with no sign of damage there. It sounds like it's coming from behind the timing cover, maybe?
Has anyone had something like the cam, gears or distributor make noises or maybe it's a bearing? Oil psi looks good though.