jcb/leyland 4.98nt conrod ovality

[MrF]

I measured the con rod out my 3ciii leyland 4.98nt and with the rod bolts torqued to 60lb/ft the con rod bearing/eye in the rod itself is 0.2mm (8 thousandths of a inch) out of round. I can't find any spec in the 4.98 manual for eye or crank ovality but on the motorcycle stuff I usually work on this would be bad but am I being too precious on conrod roundness here?

I ask, because I've put it together multiple times with the same big end shells and rod that came out that cylinder and it just feels really tight to rotate now. I am theorising that either the shell or the conrod has distorted once the torque has been let off it and re-applied...

[MrF]

And promptly answers own issue... Short version, we'll (once again) chalk this down to the joy of working on things other people have worked on.

Long version -
I'm staring at the cap under a magnifying light after posting this thinking it looks like the cap's misaligned but the cap->rod numbers align correctly, just like they do on all the other rods, so I flip it, torque it up and it looks aligned, so measure and 0.01mm ovality which could easily be me holding the bore gauge funny. So back under the magnifier for a closer inspection and realized the number on the cap looked slightly drunk and a different font. Flipped it over and there were some old hammer bruises on the other side where someone had knocked it off in the past, and could just make out a faint "3" behind the damage. So someone has helpfully re-stamped the cap, on the wrong side.
Weather broke for a few minutes I couldn't get it together quick enough (though now rather slick at it), liner in, piston home, rod down, torqued it to 30, shifted crank with spanner to get on second bolt and still free, then both up to 60 lb/ft, and its spinning really nicely now.

Head back on tomorrow as the skies opened again just as I was finishing so its back sheeted up. I'd work in the barn but its blinded ready for concrete, and I think getting wet outside lying on sheets of ply beats getting sand inside things.

[Matchless?58]

Well that's what you get for working on old motorcycles it makes you suspicious of anything anyone else has done !
Glad you sorted the issue and sounds like you are well on the way to your machine running again .
Regards Chris