I have a Milodon high volume pump, and found it to be at max spec out of rhe box! .004 end clearance, on a product that will grow out of spec (max end clearance .004) just because the aluminum housing will grow as it warms. I used a flat plate and sandpaper to bring it down to .0017, or .0002 over minimum cold. That ought to help it pull a prime now. This was not in your original post, but felt it important.