My I4 had the same problem...search for posts by Frank Grunthaler.  You can
also check my site out http://my.tbaytel.net/guskers There's a section on
an Accusump pre-oiler installation...my ball peen hammer approach to the
problem.

Another two approaches:

Try cranking the engine (coil lead off) with the oil filter loosened or
removed.  The anti-drain back valve in the filter may be impeding the flow
of oil enough to stop the prime.  Have an observer there and a pan to catch
oil.

  If that doesn't work, remove the distributor (mark it first) and use a
13mm (I'm not 100% on the size) socket and extension to drive the "key" at
the bottom of the distributor hole.  This key fits into a slot on the
bottom of your distributor.  Make sure there is no possibility of the
socket/extension coming off and dropping into the engine.  I believe
rotation direction is clockwise.  A half inch drill does a nice job for the
spinning chores.

Please post your results.  I've yet to see a definitive reason for the I4's
loss of prime at 15 degrees mount angle.

Hope that helps.