connecting rods weighing question

[Schurkey]

Against my better judgment, I'll ask:
what does the rod's center of gravity have to do with reciprocating vs. rotating weight?

Are you referring to the Buick system of "balance" where the connecting rod balance pads are supposedly at the "center of mass"?

Buick advertising made it sound wonderful. I think it's just cost-cutting dressed up to impress the unwashed. But I've been wrong before.

Image available at
http://www.rowand.net/Shop/Tech/images/ ... hing01.jpg

[BillK]

Hi, Bill,


When I say it wouldn't repeat, as mentioned, the mandrel would repeat to under one gram, but exact left/right and the angle to drill was slightly different each time.

Jack,

I just started a 400 Chevy balance job. Stock crank and rods just slightly different pistons. Just for grins I spun it three times, waiting about 5 minutes between each spin and the numbers were exactly the same all three times. Same angle and same exact weight to drill. Just for grins I will take the bob weights off and put them back on after lunch to see how much it will change. Like you said it is virtually impossible to get them on exactly the same every time.

In no way am I down playing the importance of balancing but I do think some people take it to the extremes especially on pretty much stock engines. Especially if you see how far out some of the factory stuff is and yet the engines run perfectly smooth and last hundreds of thousands of miles.

[BillK]

Since yours repeats, probably it's the precision installation and the operator being intimately familiar with the machine.

A little bit of both I am the only one that touches it.

I did take the bobweights off on my 400 crank and put them back on and tried it again. It might have changed a gram or so and the angle one number or so but nothing significant.

I also wanted to comment on the guys that say they got it within a gran or so. A gram on a crank with a 2" counterweight diameter might not be good enough compared to a crank with a 6" counterweight Grams really do not mean anything. Its oz/in that matters.

[rfoll]

When I put the big end of the rod on the scale, I have a sliver of .050" plastic shim stock sandwiched in the parting line to find the center.

[strokersix]

When I put the big end of the rod on the scale, I have a sliver of .050" plastic shim stock sandwiched in the parting line to find the center.

But you will be .025 too long! joking. I think that's a good tip.

[travis]

Someone left the door open again

[David Redszus]

Against my better judgment, I'll ask:
what does the rod's center of gravity have to do with reciprocating vs. rotating weight?

Suppose we were to weigh a con rod and then balance the rod on a knife edge.
By measuring the location of the balance point, we can determine the weight of the
big end and the small end. They might be 50-50, but probably not. The small end weight
can be added to reciprocating weight and the big end weight added to the rotating weight.

If the rods weigh the same and the balance points are the same, we have a set of balanced rods.

The rod center of gravity is used to determine bob weight and also used in torsional balancing
equations such as Holzer.

[Kevin Johnson]

If you scan the rods you can determine the center of mass for each one by pressing a button.

[racear2865]

This is the unit I made. I actually have the two top scales sitting on a 3rd scale. The two top scale have to weigh exactly what the 3rd scale weighs and since the rod is placed and slides to same location, it will repeat, I have a pin to fit every rod and have made a aluminum plug that has .002 slip clearance to large end.
reed https://www.speed-talk.com/forum/download/fil ... w&id=21632

[Dan Timberlake]

When I hover the mouse cursor over any of hardeep01's links the true URL look very scary indeed.

I wish I had a six pack of internet guided super long range stinger missiles for situations like this.

Or this -
https://www.youtube.com/watch?v=p_NS2H55dxI

[Kevin Johnson]

When I hover the mouse cursor over any of hardeep01's links the true URL look very scary indeed.

I wish I had a six pack of internet guided super long range stinger missiles for situations like this.

Or this -
https://www.youtube.com/watch?v=p_NS2H55dxI

Well a small tactical nuke would also take out the nearby convent school. So I guess serving the greater good is to have the moderator delete the posts.

[gunt]

any thoughts

https://theultimatetooling.com/en/produ ... -balancer/

[Kevin Johnson]

any thoughts

https://theultimatetooling.com/en/produ ... -balancer/

I wrote a brief email to Rossi & Kramer asking them if they wanted to provide more information on their well-crafted machine. It is not specifically mentioned in their products on their webpage.

http://www.pegrk.com

[Dave Koehler]

any thoughts

https://theultimatetooling.com/en/produ ... -balancer/

Interesting concept. Artsy but there appears to be a lot of monkey motion going on.
Since it doesn't read provide output numbers it looks like it is a mechanical comparator.
It does not show a line or a marker indicating where you set zero is though.
Kind of the same concept as the old shadowgraph weight scales I think. Is it on the line, above or below?
Better than nothing I suppose.

[modok]

Would work fine for a getting them all the same, (4&6cyl), but I don't see how it's going to give actual end for end weight measurements.