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Listeroid Engines / Re: Balancing out the Bounce---
« on: April 17, 2006, 05:58:50 PM »
Binnie,
Thank you for the help with posting to this forum!
O.K., The Lister arrived today! I have ripped the crate off of it, checked everything out according to George Bs notes, it's time to crank this baby up! One crank, two cranks, three cranks, close valve, bang! She fired first time! Bang, fired again…. she's getting up to speed, whoa, what's this? The faster those flywheels spin, the more this thing looks like a man eater…. better run! The neighbors called the cops, they reported something about a man running around the yard with a machine in hot pursuit!
My neighbors called the cops on me; your neighbors probably have more sense and will call the cops on the Lister. If your experience follows the same general format as mine, maybe it's time to look into balancing your Lister. The following is how I went about giving my Lister some semblance of balance.
Take the crankshaft, connecting rod and piston out of the engine.
Remove the piston from the connecting rod.
Install the big end bearing, bearing cap, bolts, nuts and cotter pins on the connecting rod.
Place the big end of the connecting rod on an accurate scale, the small end of the connecting rod should not be on the scale, it should be supported off scale with the center line of the wrist pin hole and the center line of the big end hole level with each other. (see drawing) Make note of this weight.
Support the crankshaft in a device which will allow it to turn freely.
Install both flywheels on the crank along with the flywheel keys.
Attach a weight equal to the weight obtained above to the crankshaft at the connecting rod bearing surface, engine builders call this a bobweight.
With the bobweight attached, start the crankshaft rotating. If you have managed to eliminate most of the friction between the crankshaft support and the crankshaft, the crankshaft will stop rotating with the heaviest spot down. Add weight to one of the flywheels until the crankshaft stops rotating at a different spot each time. What you are trying to accomplish is a balanced assembly. The assembly should not have a heavy spot that always returns to the bottom.
Once you are satisfied with your balancing job, weigh the amount of weight that you added to the flywheel, divide this weight in two and add this amount to each flywheel.
I have an Indian built Lister 6/1 engine. In my case the bobweight is 6.05 lbs.
The weight I added to the flywheel in the balancing procedure was 2.60 lbs.
Drilling a 7/16" hole through the flywheel at the counterbalance removes .04 lbs.
2.60 lbs. / 2 = 1.30 lbs.
1.30 lbs. + .04 lbs = 1.34 lbs. added to each flywheel
BE CAREFUL! Weight added to the flywheels must be secured very, very well. Imagine the force involved if a 1 lb. weight became disengaged from the flywheel turning at 600+ R.P.M. BE CAREFUL! If you have no clue about machinery or the forces involved, do not mess with this. I suggest you install the weights on the interior rim of the flywheel so that the weight is tight against the interior rim. Doing so will insure that the centrifugal force of the flywheel turning pushes the weight against the rim. In addition, I bolted the weight to the flywheel with a 7/16" bolt.
My friend Mac McQuaid suggested leaving the crankshaft in the engine and loosening the bolts holding the housing for one of the taper roller bearings so that the crankshaft moves as free as possible. This sounds like a wonderful idea to me so long as your bobweight does not interfere with the crankcase as you turn the flywheel to find balance.
This balancing is called static balancing. A good engine builder will have a machine capable of a dynamic balancing. Dynamic balancing is where the crankshaft with bobweight attached along with flywheels is placed in a machine and rotated. The forces exerted are measured so that weight can be added or removed in order to obtain the desired balance.
This method would be more precise than static balance; however, my engine is no longer chasing me around the yard and I suspect yours may benefit from this simple procedure.
Note: Since writing the above, I have questioned the wisdom of drilling anywhere on the flywheels. I suggest finding an alternate way of attaching balance weights.
Best regards,
Copybell
Thank you for the help with posting to this forum!
O.K., The Lister arrived today! I have ripped the crate off of it, checked everything out according to George Bs notes, it's time to crank this baby up! One crank, two cranks, three cranks, close valve, bang! She fired first time! Bang, fired again…. she's getting up to speed, whoa, what's this? The faster those flywheels spin, the more this thing looks like a man eater…. better run! The neighbors called the cops, they reported something about a man running around the yard with a machine in hot pursuit!
My neighbors called the cops on me; your neighbors probably have more sense and will call the cops on the Lister. If your experience follows the same general format as mine, maybe it's time to look into balancing your Lister. The following is how I went about giving my Lister some semblance of balance.
Take the crankshaft, connecting rod and piston out of the engine.
Remove the piston from the connecting rod.
Install the big end bearing, bearing cap, bolts, nuts and cotter pins on the connecting rod.
Place the big end of the connecting rod on an accurate scale, the small end of the connecting rod should not be on the scale, it should be supported off scale with the center line of the wrist pin hole and the center line of the big end hole level with each other. (see drawing) Make note of this weight.
Support the crankshaft in a device which will allow it to turn freely.
Install both flywheels on the crank along with the flywheel keys.
Attach a weight equal to the weight obtained above to the crankshaft at the connecting rod bearing surface, engine builders call this a bobweight.
With the bobweight attached, start the crankshaft rotating. If you have managed to eliminate most of the friction between the crankshaft support and the crankshaft, the crankshaft will stop rotating with the heaviest spot down. Add weight to one of the flywheels until the crankshaft stops rotating at a different spot each time. What you are trying to accomplish is a balanced assembly. The assembly should not have a heavy spot that always returns to the bottom.
Once you are satisfied with your balancing job, weigh the amount of weight that you added to the flywheel, divide this weight in two and add this amount to each flywheel.
I have an Indian built Lister 6/1 engine. In my case the bobweight is 6.05 lbs.
The weight I added to the flywheel in the balancing procedure was 2.60 lbs.
Drilling a 7/16" hole through the flywheel at the counterbalance removes .04 lbs.
2.60 lbs. / 2 = 1.30 lbs.
1.30 lbs. + .04 lbs = 1.34 lbs. added to each flywheel
BE CAREFUL! Weight added to the flywheels must be secured very, very well. Imagine the force involved if a 1 lb. weight became disengaged from the flywheel turning at 600+ R.P.M. BE CAREFUL! If you have no clue about machinery or the forces involved, do not mess with this. I suggest you install the weights on the interior rim of the flywheel so that the weight is tight against the interior rim. Doing so will insure that the centrifugal force of the flywheel turning pushes the weight against the rim. In addition, I bolted the weight to the flywheel with a 7/16" bolt.
My friend Mac McQuaid suggested leaving the crankshaft in the engine and loosening the bolts holding the housing for one of the taper roller bearings so that the crankshaft moves as free as possible. This sounds like a wonderful idea to me so long as your bobweight does not interfere with the crankcase as you turn the flywheel to find balance.
This balancing is called static balancing. A good engine builder will have a machine capable of a dynamic balancing. Dynamic balancing is where the crankshaft with bobweight attached along with flywheels is placed in a machine and rotated. The forces exerted are measured so that weight can be added or removed in order to obtain the desired balance.
This method would be more precise than static balance; however, my engine is no longer chasing me around the yard and I suspect yours may benefit from this simple procedure.
Note: Since writing the above, I have questioned the wisdom of drilling anywhere on the flywheels. I suggest finding an alternate way of attaching balance weights.
Best regards,
Copybell