Re: # 4 cylinder

Posted by Wesley Boyer On 2016/11/19 12:00:09

Phils38cpe, I don't know if got your problem fixed but I did find this about Valve Rotation, although this is from an airplane article it should still be relevant.

Valve Rotation

Exhaust valves are designed to rotate, and this rotation is essential to valve longevity since it helps prevent deposits from building up around the seat, stem, and guide. At a typical 2,400-rpm cruise, each exhaust valve opens and closes 1,200 times a minute, and each valve rotates once per minute.

Precise alignment of the rocker arm is essential for proper valve rotation. A poorly aligned rocker arm can wear out a valve guide within 100 hours of engine operation - and that wear can cause improper valve seating, hot spots, and valve damage or failure. Watch through the borescope as you turn the propeller by hand and pay careful attention to how the exhaust valve opens and closes. Note any "side step." The more a valve shifts sideways as it enters the seat, the more worn the valve guide is likely to be.

So for what it's worth I would say with it turning faster than the rest is a problem, how great I don't know.
But this is just my 2 cents.
Wes