Thank you for your informed comments Frank. I do not think the wear is because of dirty, unfiltered oil. If this was so the cylinders would be surely also affected. In the case of the engines I have done, the wear was not grooving or scoring, which would be the cas e with dirty oil, but was universal across the journal. In fact there was more wear on the crank than on the bearing. I think Willys Jeep bearings may be obtainable in white metal, as are the Hudson Jet, which are the same size as the Hudson 8, and they may be better. But the type of metal used in most modern bearings is much harder than the original babbitt, and this is where the wear is coming from. The Continental C4 bearings I used were lead/bronze, and I have not experimented further because of the bad results I had form this, and also considering that I have never used these in my own engines, and have had up to 120,000 miles service form original style bearings, both main and rods. The only reason I went to shells was that the owners insisted, and in the end it was to their cost, as I was not prepared to give any sort of guarantee. I assure you they were correctly fitted. I suppose it would be possible to calculate the pressure build-up in a splash fed con rod bearing, but in the case of main bearings, there is only gravity, and the wiping action of the journal as it revolves. Interesting topic!
Geoff

Geoffrey,
You mentioned that [color=#ff0044]In the case of the engines I have done, the wear was not grooving or scoring[/color]. A lubricant with a fairly uniformly distributed abrasive contaminant on the order of, say, 5 or 10 microns (that's a guess, but think "volcanic dust" from one of your nearby volcanos and just a quick theory, sans supporting data), would produce a pretty good finish on a worn journal, but only in the contact area which would be ~ 1.13 in. for a Continental bearing or ~1.1 in. for the Jeep insert. Both of these are significantly narrower than the poured Babbitt Hudson bearing.
If you jump back to pg. 4 of this discussion you will see that the bearings I have used are ~1.23" wide, a near match for the actual contact width of the Hudson bearing and a ~ 8 -10% increase over the Continental or Jeep inserts, respectively.
Disregarding, for the moment, the particle embedment subject, I'd have to assume that a decrease in bearing surface area would result in a proportionate rise in bearing loading, aggravating the effect of contaminated oil. A large factor [i]could be[/i] the level/quality of maintenance exercised by the owner of the subject vehicles if they were not in your direct control.
As for particle embedment ability, my approach is to remove particles through filtration, thus reducing the need for the embedment characteristic of the poured Babbitt material.
I can't claim to have developed a foolproof, reliable process for an insert conversion but [i]can[/i] lay claim to at least a short-term success with the version in our 212. 3000 miles does not a success make, but a recent inspection ( a couple of hundred miles ago) revealed that the #1 journal had no evident wear and was within .0001" (pretty much the practical limit of my instruments) of the initial diameter, and that the clearance was unchanged at .0012". If one was to assume that the "miles travelled" versus "journal diameter" relationship is a linear one, then I can expect something <.005" at 150,000 miles, a distance that won't even be approached in our lifetimes. That inspection was after putting 2500 miles on the Diesel-rated 10-40 oil which passes through filters on every cycle (reservoir to reservoir).
I'm sure that one could come up with a fuzzy number for pressure at the rod bearing (too many variables to consider) but probably has no bearing on this discussion.
F

Some humor and possibly food for thought. This was sent to me by a friend:

In looking over Geoff’s description of his experiences with insert conversions after about 15K mi, several things stand out:

1) Typical crank journal OOR by 0.006”

2) No evidence of scoring of either shaft or bearings, just regular wear

3) Similar results with three different brands of inserts.

To me, this array of evidence smacks of slow, abrasive wear. What could be the source of the abrasive? Like you, I reject the idea that the insert alloys are too hard.

Initially, I thought of a poor cleanup of parts after the machining operations. However, I think that after about 15K mi, metal chips and/or dust would likely have introduced at least some level of scoring. Besides, after a few oil changes, the particle levels should have been much reduced.

Finally, I settled on a very fine abrasive getting into the crankcase on a regular basis. What was this abrasive and how was it getting in? For starters, how about fine volcanic dust and the dual draft pipes on the splasher engines?

A look at map of NZ reveals that Wakefield, where Goeff lives, is near the northern tip of the South Island. The South Island itself seems to be volcano-free, but the North Island has no fewer than 8 volcanoes and is included in the “Pacific Ring of Fire”. Ruapehu is only ~300mi to the NW of Wakefield and is fairly active. Its last major eruption, which shut down Auckland and eleven other airports, occurred in 1996 . Another volcano on White Island, some 400mi further to the NW last erupted in 2000 . Just think of these two spitting out small clouds of ash daily, (of course there are six others which might also contribute)add some sea breezes of the proper direction, mix the transported ash with hot motor oil and you have a beautiful lapping system which after ~15K mi, has done some damage.

I suspect that the babbitted rods hold up better since the alloy might be able to effectively embed much of the particulate matter.( I'm not so sure about this, though)

If this scenario has any merit, your C-6 engine, recently modified with PCV and full-flow oil filtration systems, suffers no threat from Mt. St Helens and will run forever.
[color=#44bb00]Frank's note:[/color] The reference to Mt. St. Helens is because I live a short distance from there.

When you can stop laughing and regain your normal composure, let me know your take on this hypothesis."

[color=#ff0044]This was meant as humor but it may contain a substantial degree of truth. Factual corrections are encouraged[/color]

There is another point to this thesis. As N.Z. sits atop two tectonic plates, and these are continually grinding together, this must generate considerable abrasive dust which would be blown ashore with the salt spray. Combined with hot air which seems to drift down from the Northern hemisphere, we have a perfect recipe for specific wearing of non original inserts in Hudson engines.

Ah! "......hot air drifting down from the Northern Hemisphere". Good one.
But seriously folks, could there be something there? Hudson cranks can't be soooooo soft as to suffer wear from just a difference in bearing material hardness, especially when one considers that the modern crank, in engines producing far more power, doesn't seem to suffer a similar fate.
Too bad we'll probably never know.
Onward
F

When I approach a construction site where the air is foggy, I turn off my engine and coast past it! I also avoid active volcanoes and dry dirt roads . This is easy because New England is overly paved and there are no volcanoes nearby . . .

Since I stopped driving fast enough to loosen connecting rods (1957) I have not had loss of oil pressure (in Hudson pressure lubricated engines) or loosening of bearings in splasher engines (about 33,000 miles on a 212, and 43,000 miles on a 254).

I change my oil often, (1000 to 1500 miles on my old cars), and none of my old cars have had oil filters.

Per

Just use today's oil, 10-40 syn-tec and no bearing problems. My Hornet has 144,000 miles since rebuild and has been driven cross country 17 times at speeds to 100 and still has the oil pressure the same as the day the engine was first started. I used to race a Hudson 8 engine, splasher, and never had any problems. I used OILSUM, 30 weight, but can't find it today. It was a Springfield, Mass company. I did tilt the engine to the left to help when cornering going left. Did a few other things also. Walt.