Understanding how Lister Type Engines are balanced becomes even more important when you are building from parts, I have now either seen or have had it reported to me by reliable sources that they have received totally assembled engines from India with mismatched Flywheels!
The fact is, the production numbers of engines like the 12/2s are now very low, and Indian Erectors (as they call themselves) often can’t find, or don’t employ people who know how to build these engines correctly.
In one case, there were two 12/2s sold by Vidhata that reached a very mechanically inclined customer in Canada. When he started the first 12/2, it started hopping around like a Jack Rabbit on steroids! Now you might ask, how did Vidhata test run this engine and pass it? The Flywheel counterweights were both following the Pistons! Yes, there were signs it had been run, soot in the exhaust port, etc. but obviously, the untrained, or the uncaring still shipped the engine to the customer.
Maybe we need to look at how people in this business get paid in India, as I think it is often the case; they get paid for assembling and passing an engine, NOT for doing a job right. Another norm for India, the people you often deal with are office workers, they have very little interest in knowing the mechanical side of the business and technical questions are often passed along, and when the answer comes back to you, you know the question never made it to anyone who understood the question!
For some Indian office workers, knowing how to run a shovel and dig a proper hole is likely just as high on their agenda as understanding some machine, it is possibly beneath their position to understand these things at least from my experience with several companies, so it seems.
So now that you have the example, let’s cover some fundamentals that might help you spot potential problems.
The Standard 6/1 CS engine used a cast iron piston and a crankshaft with no counter weights on it. Many refer to this as a ‘standard crank’. In this engine, we expect to see the counters cast into the Flywheel, and when the piston is at top dead center, we expect to see both counter weights in the flywheels at bottom dead center.
But what about STOVER flywheels, or those that are concentric? These flywheels are normally mounted on counter weighted cranks, the Pistons are sometimes made of an alloy, and the whole configuration is different than what many of us refer to as a ‘Standard’ CS. If you fit these concentric flywheels “without counter balances” to a standard crankshaft engine, you may have a serious out of balance problem.
As for the twins, the typical 12/2 has a 180 degree crank, with no counters on the crank. When the piston is top dead center, the flywheel counterweight on that side should be at bottom dead center. A quick visual will show the counters opposite each other, (180 degrees) taking off the door, and looking at the crank will prove they are countering the piston and rod on their perspective side of the engine.
There are different thoughts as to running concentric flywheels on twins, most I have seen are smaller in diameter, and designed for higher RPM, sometimes 1000 RPMs, The Stover flywheels are normally used with the counter weighted cranks.
It is wise that you check your engine and VERIFY you received the right flywheels and that they were installed on your engine properly. Your safety, and others should be the number one concern.
