OK, when you remove the oil filter block off plate on the side of the engine, you will see that the casting has 2 chambers, dirty oil and clean oil. In the picture the filtered clean oil goes in the chambers outlined in yellow.
The dirty oil chamber is outlined in blue. There is also a pressure relief ball in case the filter gets so plugged up that there is no flow. The relief valve makes it stupid proof.
The cast aluminum blocking plate from the side of the engine can be transferred to directly cover the old oil filter location. It can go on without regard to placing the locating pin. Bolt it on and go. The bolt will also swap locations. That aluminum blocking plate is shown sitting above the new oil filter location for the picture. You can clearly see the chambers that need to be separated.
The large hole at the 8:30 position is connected to the hollow center bolt hole...filtered oil INTO the engine. I think the big hole at 11:00 is the connection to the other (original) oil filter and its no longer needed. I believe that's why my fancy plate does not have the hole drilled through.
And so..... the special plate has to be there to route the oil through the filter (and not bypass it). Clean filtered oil ONLY goes from the filter through the hollow center bolt. The new plate blocks off ALL of the ports under it as they are connected by a large passage about 1-1/2'' inside the front engine housing. That 8:30 hole is directly connected to the hollow oil filter bolt. That's why there are no holes in the new home made blocking plate on the clean oil side (left side)
All holes in the new blocking plate are for DIRTY oil to enter the filter. One hole is centered over the relief valve. The other 2 were conjoined.
The new blocking plate is probably 3/16'' steel and is held in by the hollow oil filter bolt. You will notice that the center has been relieved to clear the hex head. I recall chucking up the oil filter bolt and turning about half the width of the hex off. The reason....everything has to clear that hex when you tighten the oil filter.
I hope this helps!
