don't rely on sound. measuring the lash is stupid easy. far, far easier than removing the entire head. A feeler gauge can be had for all of $5.
recent rebuild now top end "tap"
- Thread starter rustfarmer
- Start date
or cam bearings..... which are easy to measure too with the engine apart. The standard 7M test for rod knock is to remove one spark plug at a time and rev to 2500 rpm. If the noise goes away then that rod is bad.
It is alot easier to just check the valve lash before you move on. Don't assume it's 100% fine just because you think it's already been done. Just check it. If they're all fine then you've wasted 5-10 minutes of your time checking it. Then move on to the cam journal clearances. Check RK by doing what c3p0 said.
Do it, check the lash, do it.
Do it, check the lash, do it.
Ok, point taken. I will re-check the lash and cam "bearing" clearance. Don't mean to be stubborn, but no one has explained how valve lash or cam cap clearance could have suddenly changed in a 5 mile period enough to go from quiet to a rather loud tap?
If bearings are loose, you can't measure or set clearances accurately. The springs load the cam unevenly and result in the cam moving relative to the valves depending on rotation position.
That makes sense and I will do the plasti-gauge check, but still, the only way I can see this happening so quickly would be if a cam cap worked loose and mine were all tight. Anyhow, easy enough to check all these issues.