TOPIC:

Face is very slightly convex, maybe half a mm at the edge. Even all the way around.

Any cracks?

None. At this point, my plan is new orings, new filter, new spring, new washer. Try again with thinner oil and a pressure gauge on the main gallery cap.

I can't decide if the filter bolt should be shortened by a mm or 2.

I wouldn't. New filter yes and O ring Yes. I use Wix filters # 24942 at O Reillys. About $5 and it comes with O tings.
Good night.
Steve

If that oil filter bolt was in place at one time and worked well I would see no reason to shorten it. Perhaps you can measure the overall length of the bolt and compare it to a new one, or a known "good" bolt to see if any stretch has taken place. I am certain someone on the forum has a new oil filter bolt and can give you the overall length. Take a close look at your bolt and make sure it has no cracks in it especially around the head or thread area. Otherwise put it all back together properly, install the oil pressure gauge and see what happens.

Rick H.

Many times when I do an oil change the O ring is big and it does not fit properly, so I cut the O ring and make it a perfect fit.

When I had Jeff weld the crank journal it distorted the case a little so oil was leaking past the O ring between the cases. Oil pressure was way down. I could see it leaking past it with the filter out. I loosened all the small bolts, installed the filter tightened it then tightened all the pan bolts. Oil pressure came back up. I wound up using a thicker O ring I cut to size at a steep angle and glued it using Super glue for plastic. Worked great. I doubt the bolt is the culprit but it may have had a ham handed PO that tightened it too much. Normally the head would be stripped if that were the case. I'd try using the washer on the outside to see if that's the problem. You can buy new bolts from a number of places or maybe a good used cover. A member here had a issue of the cover breaking. It was caused by a plug installed by the PO for his Micky Mouse oil cooler setup. Removed the plug and all was well.
Steve

I was thinking about that today. There is a big O-ring, same size as the one on the bottom of the filter cover. It's between the cases. Maybe it's missing?

hardrockminer wrote: I was thinking about that today. There is a big O-ring, same size as the one on the bottom of the filter cover. It's between the cases. Maybe it's missing?

so cases have to be split to see if it's there? Why is it there? To seal oil passage between the two case halves?

If the engine is full of oil and the cover is off there shouldn't be any oil getting past the O ring. If there is it might be missing or cracked. You would also have very low oil pressure if any.
Steve

hardrockminer wrote: I was thinking about that today. There is a big O-ring, same size as the one on the bottom of the filter cover. It's between the cases. Maybe it's missing?

There isn't a large 'O' between the cases.
Only on the filter and breather covers.
There is a small squared profile 'O' ring between the cases the same as on the oil pump to that seals the join up to the oil pressure switch.
If that was missing the oil would leak back into the sump and the oil pressure would drop so that would not be the cause of the leak.

Apologies...I was wrong. It's on the inside of the oil pan.

There is also a small O-ring inside the cases at the top of the oil filter.

If either one is leaking it would reduce pressure to the mains.