Building a "normal" motor.
If you were choosing stock connecting rods, select the lightest rods or the heaviest rods?
What would you base your decision on?
I have a large number to choose from.
743 to 789 grams.
Just wondering out loud.

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Hyper_pak

I would choose rods with the smallest balance pads and the most symmetrical machining. Those that know more will chime in.

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“Buy the ticket, take the ride.”
― Hunter S. Thompson

I'd try to go light.

But select the set that's easiest to get to the same weight/ weight distribution

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Find a set that has all 6 close to the same weight. You would never be able to measure any difference in performance, either by seat of the pants or dyno if you had the lightest set or heaviest set.

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There's no such thing as too much cam....only not enough engine!

A well centered "small end" hole is the thing I look for first. I want to see lots of material all around the piston pin hole.
I am always surprised how off-center some of these rods are and a "shift" up or down also shows its self at the big end.
After I sort for that, I find six rods that are close to the same weight.
DD

I select for the smallest balance pad on the big end, and/or the most centered holes (big and small ends). Last time I used a digital caliper to measure thicknesses of the thinnest parts around the big end and chose the ones with the thickest parts near where the rod bolt head hits the rod body. For a normal motor (under 5500 RPM), I would think any rod without damage would work great.

Lou

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Home of Slant6-powered fun machines since 1988

Thank you for your ideas. Good food for thought. I know when I take my 170 apart I am going to weigh those rods, just to see what a factory built motor had just for grins.
I was thinking as I weighed some, what if a production line motor went together like this:
These are the weighs from my small sample.
First, if a motor went together with 6-740 gram rods, that would be 4440.
Another one with 6-790 gram rods, that would be 4740, difference of 300 grams, almost 1/2 a rod.

And then after $pending a few bucks, Molinar @ 6-640=3840, over 1 rod from worst case.

Round pizza, square box, too much time on my hands...

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Hyper_pak