Balancing Pistons and Rods

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Model T Ford Forum: Forum 2018: Balancing Pistons and Rods
Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon on Thursday, September 13, 2018 - 08:20 pm:

I decided to go ahead and check the bottom end on my 24.
Everything looks pretty good, a little scoring in the cylinders, but I think a hone will be enough and a new set of rings.
#3 rod bearing has a chunk that came off the edge, I have another one that I just need to fit. Should be close after removing shims from #2, the rest will need filed a little.

My question is, I want to make each piston and rod assembly to weigh the same. What is the best place to remove some metal from the rod ? I was thinking the casting line on the side, I could grind smoother...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, September 13, 2018 - 08:30 pm:

If you use a grinder be sure to cover the babbitt. The hot metal from the sparks embeds very easily.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Thursday, September 13, 2018 - 08:41 pm:

On rods, it is not enough to make them weigh the same. The big ends and little ends have to weigh the same too.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon on Thursday, September 13, 2018 - 08:49 pm:

Does any balancing even make much of a difference in a 2000 rpm engine ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon on Thursday, September 13, 2018 - 08:52 pm:

BTW I have aluminum pistons.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Thursday, September 13, 2018 - 08:58 pm:

I've pulled down many a engine with miss-matched rods and pistons, bored to different sizes as well, engines that have been running for who knows how long. The T engine is pretty forgiving and just keep on going. It's only in these modern times that people wont to grind the crap out of everything in the name of 'balancing'


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Thursday, September 13, 2018 - 09:01 pm:

In my experience, aluminum pistons, in sets from the factory, are quite well balanced. Rods can be all over the place, as can the crank, flywheel and transmission drums. The crank and flywheel were factory balanced, but not that well and in the case of the flywheel, made worse when magnets are bolted on to it.

I like to balance engine parts and I believe it makes a huge difference at virtually any speed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth W DeLong on Thursday, September 13, 2018 - 09:52 pm:

Why can't i see anything in my mirror? It might not be a low quality mirror,it may be low quality engine work.Bud.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Cibolo, Texas on Friday, September 14, 2018 - 12:04 am:

Ken, Are you trying to say that your mirror vibrates so bad that you can't see anything out of it?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jem Bowkett, Spalding United Kingdom on Friday, September 14, 2018 - 02:19 am:

I dumped the mirror years ago, couldn't see a thing for the vibration :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon on Friday, September 14, 2018 - 04:33 am:

Never had any vibration like such, on my stroked out Shovelhead, but not my T...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Friday, September 14, 2018 - 06:07 am:

On a Model T the rear view mirror is not needed because anything behind will soon be in front.

Getting back to the thread: If you are building a high speed motor for a speedster then balancing becomes more important. It sounds like Dave is working on a more or less stock engine. In that case it is less important to balance things. I suspect the crank is not counter balanced and this will be the major source of imbalance and vibration. I would not worry about the weight of the rods being equal unless they are grossly different weight. If you want to be exact then all the big ends and little ends should weigh the same. Remove material where there is no stress. Grinding the flashing from the forging is probably OK as long as you do not go too deep. It is more important to balance the flywheel with the magnets on them and to a lesser extent the transmission drums. Mike Bender has some good videos on balancing stuff, see http://modelt-tips.com/. By the way, under most circumstances it is impossible to completely balance a reciprocating engine because at TDC and BDC the pistons are reversing and 90 degrees from there they are not.

I am concerned about the chunk that came off of number 3 rod. This may indicate that the babbitt is fatigued or that it was not cast onto the rod correctly. If that is the case then the rest of the babbitt may fail.

The yellow Time Saver can be used to fit the bearings. Again, Mike Bender has some good videos on how to do this.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth W DeLong on Friday, September 14, 2018 - 09:18 am:

Terry,No i was just trying to prove a point.After breaking a crankshaft and before the total rebuild Joe Bell said he could have the crankshaft and flywheel assembly ballanced for about 100.Best money i ever spent!!! I think a unballanced engine will lack in power as it fight's itself.I think there is several reason's the Montana 500 people can go so fast for so far!!Bud.


Top of pagePrevious messageNext messageBottom of page Link to this message  By J and M Machine Co Inc on Friday, September 14, 2018 - 09:23 am:

Dave: Best place to remove weight once you have checked the rods is on ends, you may notice in the picture how I am weighing the rod. Check all first find the lightest and then make others same on big end and then do total weight correction by removing material from wrist pin end.
Most benefit of balancing Model T is from flywheel since it has such mass. Rods are second and crankshaft is third regarding amount of improvement. Pistons usually are good out of box within 4 grams but I have included a picture showing where we remove weight from not to damage piston integrity.
You may find the rods being off alot or get lucky and have them be a few grams off.
http://www.jandm-machine.com/balancing.html




Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Friday, September 14, 2018 - 10:56 am:

Is the flywheel in that picture “static balanced” or “dynamically balanced”?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Friday, September 14, 2018 - 11:47 am:

Adam

The website posted shows the entire balance machine, putting the parts in rotary or spun balance or 'dynamically' balanced. You can see the drive belt on the flywheel assembly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon on Friday, September 14, 2018 - 02:39 pm:

Beautiful tools and work there, J and M !

Here's some pics, most are self explanatory.
Notice the 2 rods without pistons.
Was the oil hole in the rod early as opposed to the hole in the cap and dippers ?
The better looking bearing is on the one with the hole in the cap, like I have now.
I think the one with a chunk out is a bad pour.

Thanks for all your input.




Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan McEachern on Friday, September 14, 2018 - 03:37 pm:

Dave- I would seriously consider replacing those rods or getting them rebabbitted. The one you show with missing babbit is not going to last very long.
Regarding balancing rods- I pour a batch of rods, assemble them and machine big ends, leaving them undersize. The batch is then sorted into sets based on the big end and total weight of each rod.
Then I finish bore the big end to the needed size and then balance the set. It's not uncommon to see rods with big end weights differing by 20-30 grams. Yes you can get creative and remove that much material but sorting rods to get them close to equal weight is a much better solution. As far as balancing other engine components, some are not too bad and some are horribly out of balance. It comes down to luck or balance it all- its all about how lucky you feel or how well you want your car to run- kinda like a paint job- some cars are real shiny and some are not-and its the owners choice about what they are comfortable with. Hope this helps. Dan


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon on Friday, September 14, 2018 - 04:20 pm:

I am replacing the rod with a chunk out of it. I have a dozen or so to choose from.
I have done all this before, it was years ago, but I at least have a clue.
The crank looks good, so once I get the home from my buddy, and the ring set, it won't take long to get together, I plan on lapping the valves and I will block sand the head gasket surface and recheck with a straight edge. Then balance the rods and pistons after fitting the bearings.

I don't drive it hard and it's always been a good running setup, it has a Ruxstell with 3:1 gears and will pull most of the bigger hills around here.
I'll keep y'all posted.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon on Friday, September 14, 2018 - 04:22 pm:

Hone not home...damn autocorrect !!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Friday, September 14, 2018 - 07:00 pm:

Dan, might it help to approximately match the rods for weight before re-metalling them? Before I send a set off to be done, I sort them out so they weigh somewhat in the vicinity of the same weight. That way I have found it takes less work to get them in balance. I have never had the luxury of having multiple re-metalled rods from which to select.

We are coming to the selection from different ends.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Saturday, September 15, 2018 - 08:46 am:

I remember seeing a movie of Ford sorting the rods into different weight bins. I don't think the company weighed the big end separately. However, my memory is not to be trusted these days so it could have been another model Ford or even a different make.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Saturday, September 15, 2018 - 09:32 am:

Dan, I was asking because even though an industrial balancing machine “spins” the flywheel, the machine allows you to do either a static or dynamic balance. I saw material removed on the rim of the flywheel so am assuming it was a static balance, unless they started balancing it that way, then maybe have a pile of varying weight magnets they swap around at various places on the flywheel for a final dynamic balance. I was merely curious...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan McEachern on Saturday, September 15, 2018 - 11:32 am:

Hi Adam- balancing machines can perform what is called a single plane or two plane balance. Narrow rotors like flywheels, where the length is much less that the diameter can be balanced using the single plane method, which is pretty much the same as a "static" balance, because the length is not sufficient to create a separate unbalance at each end of the rotor. IN the case of narrow rotors, a static balance is equivalent to a "dynamic balance. The way this works is you essentially shut off the sensor on one support of the balancing machine. You still remove weight at the heavy spot- usually the rim, because removing it any place closer to the center would require a greater amount of material to be removed, as the amount of unbalance correction is a combination of the amount of material removed AND the radius it is removed at. Hope I answered your question.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chad Marchees _____Tax Capital, NY on Saturday, September 15, 2018 - 12:25 pm:

So there is alot of good info here, I however don't recall seeing the answer to the original question...of which I too am curious.

Where is the best place to remove material from a rod to balance them?

T rods are not like modern rods that have balance pads. So where do you take material from?

I was told by someone fairly recently that does work like this that on the light end, you can TIG weld some material to the small end, and balance them to the heaviest small end of the set. That to me is fine for the RPM generated (although opposite of building a "race" engine). But what do you still do on the big ends?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon on Saturday, September 15, 2018 - 01:11 pm:

Yeah that...??^^


Top of pagePrevious messageNext messageBottom of page Link to this message  By J and M Machine Co Inc on Saturday, September 15, 2018 - 01:27 pm:

Chad: I mentioned in my post that weight comes off on the ends of the rod not in middle.
If you notice in the picture of my prior post the rod is weighed on it's end. T rods do have two strips on bottom of rod to remove metal from.
We dynamic balance the flywheels and crankshafts.The parts have to be spun in our machine to get a proper result.
A set of rods weight matched before pouring babbitt is good start. Some rods are an ounce heavier than the next one. It's best to match them before machine work begins.



Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon N.E.Ohio on Saturday, September 15, 2018 - 03:42 pm:

Thanks J and M !!
That's what I was looking for, nice work.
I'll try to make it look pretty too, but I can get it close at least.
Ordered a ring set in .040 over from Snyder's yesterday and a cooper head gasket. Picked up the hone set today and started working on the cylinders. My friend Mike, who's a machinist has the head to make it flat.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chad Marchees _____Tax Capital, NY on Saturday, September 15, 2018 - 04:12 pm:

Thank You. For the record, I never said anything about the middle beam of the rod to remove weight though. I personally know what is done on engines with modern rods that have a real balance pads on each end as I mentioned.

Taking away minimal material in those areas on a T rod seems satisfactory. I personally don't particular favor reducing the ribs, they are there for a reason in my opinion, but when your after the best you can do, sometimes you need to do it.

But I was definitely curious what different places do as my machinist and I embark on balancing my assembly. I have been building more modern v-8 street and race engines, but this will be the oldest thing we have put together.

One thing I definitely agree upon, but some of us are at the mercy of others, is getting a as close evenly matched set before any work begins. I'm not sure where my purchased "matched set" will pan out. I was told that they are weighted as a bare rod as a total weight of each rod before babbiting. That is not close to what we are talking about here and can lead to quite a bit of variance between rods in the resultant proper balancing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan McEachern on Saturday, September 15, 2018 - 11:07 pm:

Based on many years of doing this stuff, sorting rods for total weight is not going to help when you go to balance the rods as outlined above- there is simply too much variation in the forgings for this method to be of any practical use.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Nevada Bob Middleton on Sunday, September 16, 2018 - 01:10 pm:

Last two motors had one heavy rod and one lite rod turned opposite way next to it
All cast iron pistons
From what i noticed use all heavy or light rods
Motor runs just fine key is getting good bearing and adjust right and keep oil in it
Im on the side get them close you be very ok in a low RPM motor


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon N.E.Ohio on Sunday, September 16, 2018 - 09:56 pm:

Tell me if I should start a new thread...
Ongoing progress of my ring and rod job.
I will be going with at least 2 new (used) rods, debating 3 or all. I am going to try to just make each pistol/rod assembly weigh the same by trimming the web on the cap as shown previously, after fitting the bearings. I found a set of 4 that are poured and not bored yet, but I found several decent used ones that are close, according to the bore gauge.
Have most of the marks honed out of the cylinders. Pulled all the valves, all but the last one (#4 exhaust) look great. I can lap them all pretty easily.
I need 2 valve spring pins, 1 disappeared and 1 is smaller than the rest. Anything recommended ? I haven't dug far enough at the "warehouse" of my dad's, but there's probably some somewheres...
As I mentioned, flathead V8 valves, drilled for a pin. 1.628" and less taper at the stem to face for better flow.
Took a sanding block to the block and checked with a straight edge, needed to get my smaller feelers gauge, but saw no light and.008" was a no go.





Top of pagePrevious messageNext messageBottom of page Link to this message  By Nevada Bob Middleton on Sunday, September 16, 2018 - 11:51 pm:

Get rods make sure they are straight bought from good well respected vendors still had take a twist out of them


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon N.E.Ohio on Tuesday, September 18, 2018 - 09:34 pm:

Found a rod gauge and checked for any twist...all good.
Finished honing the cylinders and lapping the valves, #3 exhaust took a little work, but the rest were not that bad. Block sanded the head surface and after all clean, I can just get a .003" gauge under the straight edge between 2 & 3...I'm sure it will be fine.
Fitted a good used rod on #3, had to shim it a little, found a whole cigar box full of rod and main shims.
Took the shims out of #2, reusing that one, removed maybe.004" and it felt perfect. (Using the slide method outlined in the factory manual) BTW, if the piston is off the rod, you can also turn the rod by hand on the crank, tight, but you can turn it without much force...2 more to go and some balancing and on to reassembly !! Got my rings today, head gasket and a couple valve keeper pins on the way...2 of the pins were questionable.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon N.E.Ohio on Thursday, September 20, 2018 - 07:45 am:

I have my rods (2) swapped to the pistons, all the bearings are fitted, pistons cleaned and the new rings on after checking gap.
Started to balance #2 to match the lightest #1....after a bit of removing metal from the ribs of the cap and still not there.
I realized #1 rod has a lot less metal at the wrist pin area. I decided to leave it be. I don't want to grind the majority of the ribs off the other 2...1&2 are close to the same weight and 3&4 are close. I would eat my hat if the old man didn't put 100,000 miles on it the way it is...

Anyhoo, a good clean up inside the block and I'll be reassembling !! Head gasket is to be here today and hopefully Mike will have the head resurfaced tonight. If so, I should have it running this weekend.


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