Exchanging flywheels between 6/1 and 10/2

[Bottleveg]

Hi Bottleveg,

I am now getting complete contradicting advice here.

You say I could exchange my 6/1 SOM flywheels onto the 10/1, and just received from the SmokStak forum:

quote:
The single cylinder flywheels are designed to balance the single cylinder engine and the twin flywheels are designed to balance a twin and they are therefore completely incompatible for obvious reasons if you look at the balance masses in relation to the key irrespective of the more minor issues of size,shape weight etc. They must not be swapped.

?

We are talking UK made engines? I guess the 10/1 is a typo?
Ask if they have the Lister part numbers for the 6/1 and 12/2 flywheels.

[michiel]

Oups... yes should read 10/2

Both engines are indeed Dursley Listers.

The 10/2 is an export one, supplied to the Belgium importer.(1930's)
All copper plates on engine show usual text in French!

[Bottleveg]

There were a few different flywheels fitted to the CS but, to save me going through all my stuff, here’s a simple one. Flywheel 25” x 3 ¾” for engines 3½ /1 (3/1), 6/1 (5/1) and 12/2 (10/2). Part number 8-5-33.

[michiel]

Will measure both flywheels tomorrow.

Even if both are same size, will weight distribution (balancing) be the same?

[Bottleveg]

Have a look at the photos that Bob posted up. I may be wrong but those flywheels look distinctly like they originated from a direct drive 3½ /1 DC unit. I’m sure Bob will let me know if that’s not the case.
If the part numbers are the same then the flywheel will have been weighted the same. I think you will find about ¼ “ difference (both diameter and face) between the standard and SOM flywheel anyway.
I guess the proof of the pudding is I did the same conversion a couple of years ago.

[rleonard]

Bottleveg,
The guy that did this conversion on this 12-2 has passed away (George Helmuth).  As I recall, Hoover's in PA (a Lister dealer to the Amish community near Lancaster) was involved.  Although it may only have been to machine in and fit the taper bushings.  Beyond that, I do not know.

The Poly barrel is for show only, not for a working, permanant installation.  Running the engine for demo it helps keep it warm.  I have had two engines sharing a barrel.  Running w/o load the water gets hot, but not to the point of any concern.

Bob

[Bottleveg]

Hi Bob,
I still find it sad when people have to leave us. I gather from your posts that George was a good friend to you.
It’s the three bolt holes just outside the taper lock I’m referring to. It’s where the direct drive was bolted on the DC units. Mainly 3 ½ /1 engines but I think I have a photo of an early 5/1 unit somewhere. Is the other flywheel plain?

[Quinnf]

Hi Bottleveg,

I am now getting complete contradicting advice here.

You say I could exchange my 6/1 SOM flywheels onto the 10/1, and just received from the SmokStak forum:

quote:
The single cylinder flywheels are designed to balance the single cylinder engine and the twin flywheels are designed to balance a twin and they are therefore completely incompatible for obvious reasons if you look at the balance masses in relation to the key irrespective of the more minor issues of size,shape weight etc. They must not be swapped.

?

Very succinctly stated.  That was probably from Peter, the forum Admin over at Smokstak.  I suspect Peter has probably forgotten more about these engines over the years than most of us will ever have the opportunity to learn.  You can take what he told you to the bank and sleep soundly.  

The question isn't so much "can you" as it is "should you."  Flywheels for twins don't have counterweights.  Any flywheel from a single will have a counterweight (spoked flywheel) or a lightening hole 10/1 or SOM, or unequal trapezoid shaped cutouts (8/1) in the web.  Those features offset the center of mass from the axis of rotation, and are used to counteract the reciprocating forces within the engine.  If you hang one of those flywheels on each end of the crankshaft of a a twin, which is already balanced by virtue of the 180 degree crank angle, the flywheels will exert a lot of force on the crankshaft and impart a rocking motion along the axis of the crankshaft.  It might not cause any problem other than some vibration, or it might end up snapping the crankshaft after a while.  In the case of a 6/1 flywheel the counterweight weighs 3 lbs, and the centripetal force generated by the weight spinning at 650 rpms is 120 Gs, or 360 lbs. on each end of the crankshaft.  That's 720 lbs of force spinning around doing nothing but bending each end of the crankshaft.   Metal fatigue is cumulative.  

Bob, correct me if I misunderstood what you said about that engine.  Did you say the crankshaft on that 10/2 snapped after the SOM flywheels were fitted, or was that before?

Quinn







  

[michiel]

Thanks Quinnf,

Very clear and informative!

[Bottleveg]

Well that will teach me for talking without checking!
Quinn is quite right.
I checked my past notes and one 6/1 SOM flywheels had spun and worn the bore. Both were machined out and fitted to a 12/2 but, most importantly, one was reset to suit the twin.
So I was half right (completely wrong really). Only the driver’s side flywheel is common to both engines.
Sorry to cause any confusion. I’ll make sure I’m awake in future!
Only one thing Quinn, the 10/2 had cast iron pistons. It was the 8/1 and 16/2 that had aluminium.

[Quinnf]

Will one of you guys please tell my wife?  I don't let on, but I keep track, and I can't even get close to 0.500.   

And, you're right, the 10/2 had cast iron pistons.  I was thinking of the Indian 10/1 which, like the 8/1, has aluminum pistons.  Don't tell my wife!

Quinn

[listeroil]

According to these part numbers the heavy nongrooved flywheel is the same on the 6/1 and the 12/2.
As far as I am aware the only difference between the 6/1 heavy grooved and the 12/2 heavy grooved, is the amount of grooves 2 on the 6/1 and 3 on the 12/2.
But not sure of the key position on the grooved ones
The below information is from Lister book 585 /267