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TX fanatic 
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Joined: 09 Jul 2012
Location: Central WI
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 Topic: New pistons for a C?
Posted: 17 Aug 2012 at 10:10am |
The C that I'm restoring was left outside for a bit, One of the cylinders ended up with a some water in it due to an ill fitting exhaust pipe. Someone must have tried to start it and the rod was bent into a pretzel, the bottom of the sleeve and piston was broke off. Now to my question... The rebuild kits for the 125's come with aluminum pistons to replace the cast iron ones. How will the weight difference between the two affect the balance of the engine? I am having a hard time trying to figure out how you can take weight off the pistons without removing some weight from the counter weights on the crank. As I was typing this possibility came to mind
The crank is balanced by itself. and the pistons balance themselves during rotation so there is no need to adjust the counterweights on the crank for different weight pistons? Any clarification on this would be great!
Thanks Steve |
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Dick L
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Location: Edon Ohio
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Posted: 17 Aug 2012 at 10:38am |
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When balancing an engine each piston and rod must weigh exactly the same. If they don't the engine is not balanced. Some have been able to get by though with two pistons lighter of the same weight using one up and one down without a great vibration. Of course the crankshaft must be in balance as well as the flywheel. You would not tinker with the crankshaft or flywheel balance to justify pistons being of different weights.
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Protrucker
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Posted: 17 Aug 2012 at 10:50am |
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I think I would just buy a whole new set of pistons & rings......probably sleeves too.
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"ALLIS EXPRESS" Allis Chalmers  1944 B, 1949 B,  D14, WC
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SteveM C/IL
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Location: Shelbyville IL
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Posted: 17 Aug 2012 at 1:07pm |
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.....don't believe you'll find any counter weights on an AC 4cyl crank....
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Dick L
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Posted: 17 Aug 2012 at 1:33pm |
 SteveM C/IL wrote:
.....don't believe you'll find any counter weights on an AC 4cyl crank.... |
They balance the crankshafts by drilling holes or grind material off to lighten a place rather than add weights. Same with flywheels. Check them close and you will see where they have been balanced. Remember crankshafts are castings that are not exactly the same and must be machined and ground but not every inch. Just the ends and journals are ground. When done they will not be in balance.
Edited by Dick L - 17 Aug 2012 at 1:38pm
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TX fanatic
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Posted: 17 Aug 2012 at 2:56pm |
WOW lighting fast responses!!!
Thanks for the information I can sleep easier now. I am planning on buying 4 pistons and sleeves to rebuild this. The information on the crank balancing takes a load off my mind. The engine is at the shop but there's an issue....Because I dropped it off with the bent rod removed he measured that journal. The rod journals have been turned down 30 already and need more turning from the water damage. He said he thinks he can get +60 bearings for the rods so that's not an issue. He needs time to take out the crank and measure the mains. I hope there's enough meat left for another turn down as he thought that +30 was the largest oversize main bearings he could get but wasn't sure.
I'll keep ya'll posted
Again thanks for the reply's
Steve
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JimD
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Posted: 17 Aug 2012 at 3:46pm |
I would plan on replacing the crank or welding and re-turning that crank. I have never seen .060 bearings for the 125 engine. In fact, sometimes .030's can be hard to find. We sell clevite bearings and it seems they only produce them in large batches. When they go on back order, it might be 4 months until I can get them again. Figure out the crank, and order a good kit and the tractor will outlast you. JimD
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GregLawlerMinn
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Posted: 17 Aug 2012 at 6:19pm |
I'm with Jim D. If you need to grind the crank 0.060, look for another crank (any B/C/CA) all have the same engine and are readily available from the tractor "parters" and are fairly reasonable. The C/C/CA engines turn at 1600-1800 rpm. I don't believe that balancing the pistons/cranks is worth the extra $$; however, if you are going to soup it up for pulling and turnng the engine at 2500-4000 rpm; balancing may be worthwhile.
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What this country needs is more unemployed politicians-and lawyers.
Currently have: 1 D14 and a D15S2.
With new owners: 2Bs,9CAs,1WD,2 D12s,5D14s,3D15S2s, 2D17SIVs,D17D,1D19D;1 Unstyled WC
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dave63
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Posted: 18 Aug 2012 at 8:52pm |
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I just ordered a in frame overhaul kit for mine instead of just replaceing the rings. I was supprised to find that the overhaul kit wheren't that much more then rings and gaskets.
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The universal answer to all questions is yes, how much do you want to spend?
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Dick L
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Posted: 18 Aug 2012 at 9:51pm |
GregLawlerMinn wrote:
I'm with Jim D. If you need to grind the crank 0.060, look for another crank (any B/C/CA) all have the same engine and are readily available from the tractor "parters" and are fairly reasonable.The C/C/CA engines turn at 1600-1800 rpm. I don't believe that balancing the pistons/cranks is worth the extra $$; however, if you are going to soup it up for pulling and turnng the engine at 2500-4000 rpm; balancing may be worthwhile. |
What I was saying is that they all are balanced at the factory when being manufactured. Messing with them would be counter productive. Placing one light piston will take it out of balance at any RPM above an idle. Like knocking a balancing weight off a wheel.
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