The Steamboating Forum

Just how tolerant are our big ends? The HP little end overheated last season and there was a dry squeak from the HP area. Opened the little end, black crud burnt on the shells and spindle. Very delicate scrape and polished of surfaces by hand. Seemed smooth, solid and free turning.
Big end only contact on about 50% of the surfaces. Slightly more energetic scrape of the shells and cutting of oil channel across surface. Now free turning but very slight side to side movement(you can just see the oil meniscus deform, no room for a feeler gauge). In the light of the CV lock down, do I just put the engine back and "suck it and see" ? It is just such a fag getting it in and out and re aligned.
At least the bilge is clean !

I take it you mean "end float"? It is of no matter, and better that there is some. As long as the shells are gripped in the rod and the clearance is minimal it'll be fine.

Might check the clearance with some Plastigauge. Dirt cheap.

https://www.plastigaugeusa.com/how.html

Moly lube oils can take far more pressure than conventional oils without this additive.

You might take a look at PV values for your bearings; so long as you're within the safe values for the bearing materials and the supply of oil is adequate, these will likely be ok. Extra clearance causes noise pretty quickly, of course. The little ends are tricky, with very little motion to set up an oil film; here's where moly can save the day. There's often not a lot of extra space in some of the cross head designs, either.

- Bart