In the process of testing various oil filters for my 71' GT.
Starting of with Bosch filter(Autozone, $5.99) bit expensive but cheap compared to engine damage. This time I decided to test the anti-syphon valve before I stuck it on the engine, by blowing into the filter and then also drawing back through it, the valve was doing its job, The Bosch atleast passed this test. The Purolator Pur-one that I pulled off , has appeared to have failed, when I pulled it off, it was totally empty of oil(after sitting for about two weeks) and the valve failed the air test.
I also got a doner new Crossland filter(Another MG recommended filter) from Sportscar Warehouse to test, it will go on after the Bosch runs through 3000 miles af testing. He didn't have any Uni-parts available at the time.
My only main concern is to find out which filter can successfully hold oil in it, so I don't encounter dry pumping the engine after long periods of car sitting.
Keep everyone posted.