[ford38v8]

Ziggster, your block can be set up either with a full flow or a bypass system. The image you loaded in post #1 is full flow, and the line drawing that Will D. loaded in post #7 is a bypass.

The grub screw shown in your image must be removed if you want a bypass, and the top inboard tapped hole needs to be plugged. In comparing blocks, you'll see that Canadian blocks had that 3rd hole, while American blocks did not. The oil pan is the return location for your block, while earlier returns were either to the fuel pump stand or the distributor, through a hollow mounting bolt.

In deciding which system to use, consider first that modern detergent oil is far better than any oil available in the flathead era, in that it keeps impurities in circulation to be filtered out, while the original non detergent oil permitted impurities to settle overnight, becoming sludge in the pan and in the lifter ledges. There was no authorized oil filter accessory until 1936, which meant that settling out the impurities was a good thing for that reason, allowing a longer period between oil changes.

To compare the two systems, know that a bypass system will filter smaller particles than a full flow, without dropping the oil pressure. In addition, contrary to intuition, a bypass will filter close to 100% of all the oil in about 15 minutes driving time. It is for these two reasons that I am firmly opposed to converting a flathead to full flow filtration.

You will no doubt get opposing views on the subject, but in the end, it's your choice, including no oil filter at all. The one thing we all will agree on is the need to change oil (and filter) often and regularly.