Well, that was anti-climatic.
Before you look at the detail photos keep in mind this engine has somewhere between 50,000 and 75,000 miles on it. Hasn't been opened in all that time. I didn't start tearing the engine down until about 930 tonight, but once you get going it tends to go pretty quick. Pulling the heads off revealed nothing but a lot of carbon. The engine was definitely running rich on the kadrons! Pistons, cylinder heads and related items were all in perfect condition. The rings look great, the skirts have some wear and light scoring but the cylinder walls still have complete cross-hatching on each of them with no signs of wear. The piston-pin bushings in each rod still have cross-hatching in them. So far, things were looking good!
I pulled the oil pump, and each of the additional stages looks perfect and brand new. The "inside the case" portion shows some chatter marks under one of the gears, and the hole for the drive shaft shows some strange scoring and marks. It's possible the metal came from here, but it's just as possible that metal from elsewhere is what caused the damage. I'm going to try and refurb the housing with lapping compound, etc. If not I'll have to get a new housing for this section.
After the pump I pulled case apart, and discovered that I apparently use "lube-a-lobe" lifters! I've read so much about how bad they are, but thankfully each of mine look fantastic.
The cam bearings, however, have seen better days. I'm now starting to understand why some of the chips in the oil clearly looked silvery and aluminum-like, while others had a distinct yellowish color. I thought that I was going to find the timing gear bad, but instead it could have been copper sparkles.
The cam surface shows some matching wear, but definitely no where near as bad as the cam bearings:
Rod bearings all look perfectly good, and the main bearings show even less wear.
So at this point, I don't really have a smoking gun. At the same time, however, I have a relatively easy fix on my hands. I suspect that this is a combination of some swarf left in the tank after drilling and welding in two bungs, the oil pump chatter and the worn cam bearings. Can't really be anything else...?
At the very least I need to swap out the cam bearings. I'm going to do the crank and rod bearings as well, since I'm already in here. Otherwise I'm going to clean it, button it up and make sure I flush the tank and lines extremely well. I'll run some cheap oil for a day to flush the system, and then replace it with my usual 5w40 synthetic.
-Dave