Oil pressure problem when starting

On my 340 I have the adapter pointed looking at the end of the filter at 8 o clock..the little hand.

I also use the short filter. Maybe I should use the larger size?

I would angle the housing downward. Was the oil filter heavy like it was full? If not you found the problem, well at least that is part of it. The oil filter should be full all the time. It may have been the lifters knocking and no damage done.