[chrs1961815]

Been chasing an engine knock for a few weeks in my roadster. This is on a newly rebuilt engine with almost 1000 miles on it. Along with the knock a cylinder is misfiring (either 3 or 4, they both change a bit when shorting out). It is definitely coming from the back of the engine. The knock is not consistent in pattern and is quite loud. It is definitely at camshaft speed and in the top end.

Here is what I have checked:
Timing gear - no broken teeth, nice and tight;, plunger spring good
Compression test - all four cylinders are putting out over 60 pounds
Oil pan - taken off and crankcase inspected, nothing
Valves - valve cover taken off, clearances checked, no stuck valves (at least at time)
Just for kicks I put some marvel mystery oil in the gas to see if anything would happen, no change.


Me and many other guys have not been able to pinpoint where this noise is coming from' just on the top end in the back of the engine. The thing that seems to be making everybidy scratch their heads is that it is really loud at idle but once you increase the throttle it quiets and turns more into a rattle.

Anybody have any ideas as to what it is? We are all stumped!