Loose wrist pin bushings happen when the bushings are replaced without the proper equipment.  Sunnen makes a set of tooling for the job.  The bores in the rod are not smooth, they are rough bored.  Then Ford swedged the bushings in place, and the OD of the bushing was forced into the rough bore in the rod.  If replacement bushings are simply pressed into the rod, the bushing OD is sheared, and the fit in the rod is only temporary.  With the pounding of the wrist pin, the OD of the bushing starts to conform to the rough bore, losing its press fit.  Then it is loose and makes noise.  Sunnen tooling (I'm sure other companies have similar tooling) swedges the bushing in place, then you can hone it fit.  If peeot's engine has one bushing loose, I would suggest that the other 7 are in the same shape.

John - "The Hoosier Hurricane"

Hoosier, that explanation makes sense. Not knowing the engine’s history, I can’t say for sure whether the piston pin bushings have been replaced.

I dropped the front main bearing cap and found this:


Looks to me like original 1956 bearings suggesting that this engine was never overhauled. No more babbitt but bearing surface feels perfectly smooth. Just worn out I guess. I have about 30-35 psi hot oil pressure from about 2000 rpm but it’s very low at hot idle—less than 10 psi.

It appears the engine is due for a rebuild, but that won’t be in the cards for me any time soon.

Would it be worth the money to put a set of standard size bearings in at this point? I don’t push this engine hard and mostly just cruise around. If I’m not doing/risking lasting damage by continuing to do so, I might prefer to just button it back up and keep motoring until a good opportunity to rebuild.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive