The PH-8A is a full flow filter like I use on my Y-Blocks. It was never meant to be used as a by pass filter.

http://www.framcatalog.com/PartDetail.aspx?b=F&pn=PH8A%22
A full flow filter filters all of the oil and has the capacity to filter all of the oil the pump puts out. Because of this capacity, it is not designed to filter smaller particles. A bypass filter has much denser media and filters much smaller particles, but it filters only a small portion of the oil.

http://www.framcatalog.com/PartDetail.aspx?b=F&pn=C4

If you are pulling oil supply off of a T, it is plumbed as a bypass filter. If you have a PH-8A hanging on your firewall, it is just a worthless piece of junk that you should get rid of. Whoever installed it probably knew about as much about engine lubrication as you do.

Baldwin has a good article explaining bypass and full flow filtration.

http://www.baldwinfilter.com/ProductHighlights102011.html

Baldwin is one of the major suppliers of filters used on Diesel engines.