Rod balancing

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Model T Ford Forum: Forum 2016: Rod balancing
Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Gould, Folsom, CA on Sunday, April 24, 2016 - 10:22 am:

Have a set of rods I need to balance. Both ends. Where are the best places to remove material?


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Warren on Sunday, April 24, 2016 - 02:17 pm:

On the large end, it would be wise to cut an oil passage through the babbitt in line with the rod beam on each side using something like a round file. You can adjust the size of the opening to get the weight right.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Evan in Paso Robles on Sunday, April 24, 2016 - 10:50 pm:

Hello Richard,

On the large end if you are planning on using dippers you can drill larger holes to remove some weight. Also you can remove metal from the two "fins" on the cap. You can shave off some of the rod cap castle nut. You can also add weight to the light ends by changing rod bolts to longer hex head bolts with one side ground to fit the rod and using a self locking nut.

For the small end of the rod you can remove weight from the piston pin, i.e. grind it shorter. You can also remove a small amount of metal from the pinch bolt head surface, leaving enough to get a socket on. You can add weight by using an Allen head cap screw and washers for the pinch bolt. Be sure to drill the Allen head for a safety wire.

Remember that you are trying to balance the entire rotating assembly so you can weigh the rod bolts, pinch bolts, pistons and piston pins and mix and match to get the weight as close as possible before starting to remove metal.

Just my thoughts for your consideration, as there are always many ways to "skin a cat".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Monday, April 25, 2016 - 08:11 am:

This is how one engine builder does it. I would use a different rod before going this far though. This would indicate a mismatched set of rods anyway.



Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Monday, April 25, 2016 - 08:47 am:

Ken, that treatment looks a little drastic. However, it has one distinct advantage over grinding the rod to remove metal. The drillings will not get hot enough to be embedded in the white metal of the bearings, unlike grinding particles.
I have never done it this way, but it does make some sense.

Perhaps there would be no need for such action if the rods were match weighted before remetalling.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Monday, April 25, 2016 - 10:02 am:

On the large end you can equalize by taking the lightest rod end and adding the other three with a washer if needed.

Just polishing the rod itself taking some of the rough casting off really helps, remember to only do the polishing on the upper end if that's what you are balancing

I use a paint balance scale it makes it easy to equalize each end and equalize the total weight

Slow job to each his own!

I bought a T from orange county that had a professional job with plates welded to the rib sides and some polishing. The rods were equal in total weight but not equal at each end.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Monday, April 25, 2016 - 12:00 pm:

My brain is not awake this morning------I should have said take the heavy large end and add a washer some times two to the light ends of the other three rods to equalize.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Monday, April 25, 2016 - 12:02 pm:

My brain is not awake this morning------I should have said take the heavy large end and add a washer some times two to the light ends of the other three rods to equalize.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Gould, Folsom, CA on Monday, April 25, 2016 - 01:12 pm:

Thanks for all the helpful suggestions!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Robison on Monday, April 25, 2016 - 01:30 pm:

This is another way to lighten rods to make them come in to balance. These rods are balanced to the MT 500 spec. Which paraphrased: says one rod and piston assembly must be unaltered. This makes things tricky because every thing has to be balanced to the lightest rod. Often ends need to have weight added or even more removed so tricks like longer bolts or drilled/hollowed centered bolts are needed. You can see the ribs are removed on the cap to make the big end come in to weight. This has no adverse side effects because the rod takes the load.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Monday, April 25, 2016 - 01:49 pm:

Gad!! I have great respect for the 500 boys


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting, Clare, Iowa on Monday, April 25, 2016 - 09:05 pm:

There is only one way that you should start out balancing a set of rods, and there is no trick to it, it is called common sense.

You start with 4 rods that weigh the same, then you don't have to butcher rods like the one I see.

No bolt drilling, changing nuts around, adding washers, grinding metal off.



Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting, Clare, Iowa on Monday, April 25, 2016 - 09:36 pm:

The best place to remove metal on the pin end is the cap first, as the cap is over center of the rod and that weight reduction will be the fastest, and save the most weight removal from some where else. You start with the heaviest to the lightest, as it is the standard to lighten the 3 rods.

On the wrist pin end, you add weight on the 3 lightest rods, to match the heaviest. It is always better to ad weight, then butcher the wrist pin end of the rod. I use a wire welder and lay it in the pocket on both sides if needed. Do it about 2 to 3 grams at a time, and then hit it with an air hose until cool enough, for the next batch.


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