rod weight balance

[JW2000]

I understand one must try to get the rod weights as close as possible. However, what if they are close, but when you weight the long rods and caps seperate then they are diffrent.

For example

1.-- long rod is 438 and the cap is 154 = total 592
2. -long rod is 425 and the cap is 164 = total 589

Total weight is close but each ends are far apart. long rod is 13 grams difference and cap is 10 grams difference.

I guess the rods are from diffrent engines..... unless that is normal?

Is that a major issue? It was running like that prior. Is it important to try to find a matched set? or no big deal just as long as the total weights are close.

thanks in advance

[Henry Schmidt]

Our target number is .5 grams overall and end to end.
Any discrepancy greater than 9 grams at the start makes the set unusable.

Last year, I tried to get a set to .1 grams and spent 2.5 hours in a failed effort.
My guys got a pretty good laugh out of that.

[Dpmulvan]

Originally Posted by JW2000

I understand one must try to get the rod weights as close as possible. However, what if they are close, but when you weight the long rods and caps seperate then they are diffrent.

For example

1.-- long rod is 438 and the cap is 154 = total 592
2. -long rod is 425 and the cap is 164 = total 589

Total weight is close but each ends are far apart. long rod is 13 grams difference and cap is 10 grams difference.

I guess the rods are from diffrent engines..... unless that is normal?

Is that a major issue? It was running like that prior. Is it important to try to find a matched set? or no big deal just as long as the total weights are close.

thanks in advance

You need to weigh each end of the the rods assembled. 9 grams is the limit. Any fixture like the one below will work.

[JW2000]

oh.. so if i understand correctly. Even though the cap weights are way off from each other.. when connected and when i balance weigh them, i could still be in spec?

[dannobee]

No. All of the big ends should match and all of the small ends should match.

You weigh the two separately because one is "rotating," the other is "reciprocating."

That is, if you want to do it correctly.

[stownsen914]

But don’t weigh the caps separately, that doesn’t mean anything by itself. It needs to be done as shown in the photo dpmulvan posted above.

[Dpmulvan]

Originally Posted by JW2000

oh.. so if i understand correctly. Even though the cap weights are way off from each other.. when connected and when i balance weigh them, i could still be in spec?

Yes.