connecting rod needle bearings? (small engine)

it's possible, but you're correct, a full compliment is much more usual if there's no cage. maybe this engine has been disassembled before and one/some got lost at that time?

even if they contact, there's insignificant load between them - essentially just the weight of the roller divided by the contact surface area. trivial.

uniformly enough to bear the load. conrad [caged] bearings are not full compliment, but they handle load ok. so as long as the fill on your bearing is sufficient to not allow gaps much greater than would be in a conrad, it's not going to be a problem.

Should be bearing all the way around,

Here is a photo of one,

I think that's a crankshaft bearing. These rod bearings are a set of loose rollers. You have to set them individually around the journal.

George

I seem to recall working on some U-joints and noticed the same thing, the "needles" just floated loose and there weren't quite enough of them to completely fill the available space but there was not nearly enough free space for them to get sideways, perhaps the equivalent free space of one and a half needles.

ISTM they can't possibly go shoulder to shoulder, because as you say below, they'd be fighting each other. They will all be rotating in the same direction. That's fine when it comes to the rod and the crankshaftt, but if two needles are touching each other and turning in the same direction, they will be moving in opposite directions where they touch.

I have no experience with an engine, but istm you only need enough needles to go 75 percent around the cricle (probalby fewer) because if by some miracle, they all get jammed up in 270^ of the circle, the crank still won't escape from within their partial circle. The rod won't touch the crank and rub against it.

But that miiracle will probably never happen and the needles will space themselves out around the entire circle, not necessarily evenly but evenly doesn't matter. .

All pure theory, but you're just filddling around.

Exactly.

more or less uniformly. The goal is for the rod to not touch the crank

needle bearings are very frequently configured like this, particularly for high load applications. as for the rollers, there is only a trivial [own weight effectively] load "where they touch", and they're lubricated, so there is no problem with it.

it's called "full compliment"

That's the trouble with theory. At least my theories. Thanks.

And if I ever do what the OP is doing,, I'll be much farther ahed

I found the same thing on a Lawn Boy 2 cycle lawn mower engine. We're beginning to see a trend...maybe they intended them to be that way?