Connecting rod identification

[tubman]

Originally Posted by Bored&Stroked

It is not as easy as you think - you have to balance each end of the rod separately and you have to have a fixture to hold one end and weigh the other and it has to be exactly repeatable each time you take the same rod on/off the scale.

I made a special fixture that has a big roller bearing for the big end, so I could accurately balance the small ends.

This should give you an idea:

Attachment 578800

I have to believe that a simple "knife edge" fixture would get you close enough that it wouldn't matter on a low rpm street engine. Actually, I would worry about the "big roller bearing" having enough friction to throw a monkey wrench into the process.

[Bored&Stroked]

Originally Posted by tubman

I have to believe that a simple "knife edge" fixture would get you close enough that it wouldn't matter on a low rpm street engine. Actually, I would worry about the "big roller bearing" having enough friction to throw a monkey wrench into the process.

The challenge is that the rod needs to pivot on the exact same fulcrum for there to be a repeatable weight on the other end. I started out with just a round piece of polished bar-stock for the big-end . . . couldn't get repeatable weighs . . . had to keep testing other methods.

Then I use another fixture that holds the small end, such that I can weigh the big end.

When you start screwing around with this stuff you rapidly find out that if you can't repeat the measurement within a gram - you're wasting your time.