Last night found the detail that I missed and why the cam walked in, aside from not reusing a pressed on aluminum gear. My dumb ass pressed off the cam gear and thrust plate from the old cam, did a thorough cleaning and inspection and found minor pitting on two back lobes that sat in water. I decided to get a new cam, install my old key and press on the thrust plate and gear. I used two online Merc. manuals for reference.
The exploded view drawing was off mislabeling and placement of a "washer", and there were two statements found in other places that just didn't jive with me. One statement was that the camshaft had 4 bearings. Clearly looking at the shaft and block bearing journals, I could see there were only 3 places for bearings. Down towards the bottom of the manual I saw tolerances of .005 and not more between the "thrust plate and the cam gear" and online elsewhere saw mention of a cam gear "thrust washer."
Today I searched the garage under the press and the fridge, etc. looking for this unseen mystery "thrust washer" without luck. Then I thought, what if it was for older models? What if it never came off the old cam? I couldn't have missed that! I found the old cam, and low and behold, there was the small piece that I missed that brought my "perfect rebuild" to an engine failure. I was able to press on the old gear and check for spacing with a few assertive palm strikes today. It's not showing any wear or signs of a wobble, but I I will definitely be heating a New cam gear and freezing the camshaft before re-install.
$h@! all comes around. 30 years ago as a kid after doing my first engine head change; the OHC head on one of my first cars, a 1972 Opel Gt, I over tightened and broke the cap off this cheesy plastic camshaft end-spacer bolt, and thought, how important could it be? I found out the hard way 50 miles later when I sheered the cam gear off.
Lesson refreshers: Even the smallest details matter with the tight tolerances of engines. Possibly a beer or two during disassembly helps us to overlook the little, but important details.
I hope the posts of my engine misfortunes help others here looking for 3.0L rebuild guidance. Thanks again to all who gave great input, helping to get me back on the water!
