I had a suboptimal day yesterday.
I had done an oil change followed by a 1hr test flight all good,followed by a trip out to a satellite field when things went bad.
My engine sounded off? Gauges showed nothing abnormal so I headed back to base.

My engine was sounding like it had split an exhaust,then the oil pressure and revs began to drop.30 psi rather than 55psi,4800 at 27inches where I would expect to see 5500rpm.
on reaching my home base after 10 min? Shutdown saw a lot of smoke pour out the cowling

The problem was traced to a braided hose on the tank to pump circuit had failed internally and was sucking air which I believe let the lifters bleed down?

On shutdown a small amount of oil flowed out and onto the exhaust causing the smoke,the pipe was replaced an extended ground run was done with all appearing normal,another flight of approximately 1 hour failed to show anything different to normal operation.

I plan to get to the hanger to investigate further tomorrow.
I will remove the rocker covers and inspect the retainers and valve stem to head length in case the valves have stretched.I can't find online an acceptable length to use as a baseline,the engine is an early ul with dual valve springs.

Is there a published valve length,and procedure for checkling after this sort of problem?
Cheers
Dusty