Hi John, What brand bearing inserts are your new ones. I’m tacking this clearance issue.
Test pump like shop manual
shows. Fool around with it & you’ll. Soon see how the test works. Basically fill the entire bore with oil from your pumper oil can. Finger over fill port.
Put in piston. Allow oil to exit fill port until goes down a little. Then hold tight & bleed air out discharge port until piston is nearly to bottom of stroke. Then with finger very tight on fill port pull piston outwards to create strong vacuum on check ball. Hold this vacuum for at least 15 seconds. During test hold pump horizontal with light reflecting on oil in discharge port.
Oil must not drop in port. Not even a trace. Any drop is a failure.
A good pump will hold for a long time. Sure eventually air will bleed around piston, but the should seal 100%. My new Morgo held for over 3 minutes. My hand got tired & I quit.
The feed valve seat seems show little wear even after 30-40+k miles. Return (scavenge) seat can take great wear. Gets deeper, rough, out or round. Ball stays pretty round though. I’ve seen this wear on 100% of higher miles pumps now.
I’ve not had good results seating ball with punch. Could you lap it with new new ball & replace ball? Sure, but compared to the width of new seat, it’s too wide. So I replace worn pumps.
Wear in drive block shortens effective stroke, reducing volume.
A worn pump or leaky check ball in pump, will reduce volume. Worn/ leaking enough you have problems. Small leaks you can’t tell until oil light winks at idle or the like or return becomes erratic.