Small Continental Oil Press???

What can anyone tell me about "loss of oil pump prime" on a small
Continental?

I have heard of it in the past and it has happened to me.

The engine in question is a C-85 that has been very recently overhauled to
new limits. The case and accessory case was overhauled by ECI. New oil pump
gears, oil pressure relief plunger, etc etc.

It has an oil filter adapter that mounts where the oil cooler would mount.

I drained the oil and filled the sump immediately, the filter came off a day
or so later and a new filter was put on. Now the engine sat for ten days to
two weeks before starting. No oil pressure on start up. Gage is just fine,
it really is a case of no oil pressure.

At the same time I was doing the same thing to an 0-200 configured the same
way with the STC oil filter. About the same time lapsed between replacing
the filter and starting the engine. Oil pressure came up on 15 seconds.

An annual was being done on two planes at the same time. This accounts for
the delay on the oil filter change and the start up.

Why did the pump loose its prime? How best to get the prime back? What can I
do to prevent this in the future.

I suspect the oil filter mount has a great deal to do with this problem.

Any enlightening comments would be appreciated.

Thanks

Paul Anton