Dating a JP2M

[frangar]

Ive been chatting to a chap on a Lister facebook group from Tasmania who has this JP2M thats not in a boat at the moment. He was after some more information and put up this pic of the serial number plate....now from what I understand the number makes it a very early marine JP...I think the number makes it mid 1933 which means the first year of JP production as I understand it. However the HP rating at 30HP is confusing...especially as the other part of the number says 18/2/M which I take it is 18hp 2 cylinders and M for marine. 

 

He has a video of it running and it sounds sweet with 15 psi oil pressure....it also has side decompressors which I think means its an early one...its got the raised hand start/water jacket expansion  box etc and he says the serial number is the same on the flywheel so looks to be a fairly original engine....only the water pump looks like its been changed.

 

Any thoughts about either the dating or the HP rating?

 

 

 

[matty40s]

I know some people love their engines, but I thought you were taking things a bit far until I read the rest of your post.?

[frangar]

8 minutes ago, matty40s said:

I know some people love their engines, but I thought you were taking things a bit far until I read the rest of your post.?

Mines more reliable than most women!  

[David Mack]

Some oddities here. The serial number of 72132 doesn't fit any of the CS or JP engines according to https://www.stationaryengineparts.com/Lister-Engine-Dating/.

But the CS identity was only used on the early examples of what later became the JPs. 18/2  was used to describe the early 2 pot engines (18 hp @ 1000 rpm) but the later JP2 models were rated at 21hp @ 1200rpm. 30hp (@1200rpm) was the rating of the JP3, so definitely wrong here.

Makes me wonder if the plate is a fake!

[zenataomm]

When I was at Lister in The 80s they told me to date an engine firstly ignore the end section which describes the build.

The first part of the serial number ends in two numbers, that is the year.  So in the above it would indicate 1932.

 

They discovered that prospective bulk buyers (the likes of councils etc) would visit suppliers or even Dursley itself, check serial numbers and cherry pick the ones they wanted.  Leaving Lister with machines that could be years old, brand new but aged.

So they started adding 50 to the number of the year of manufacture, so a product made in 1966 could display a serial number ending in 16.

 

[frangar]

9 hours ago, David Mack said:

Some oddities here. The serial number of 72132 doesn't fit any of the CS or JP engines according to https://www.stationaryengineparts.com/Lister-Engine-Dating/.

But the CS identity was only used on the early examples of what later became the JPs. 18/2  was used to describe the early 2 pot engines (18 hp @ 1000 rpm) but the later JP2 models were rated at 21hp @ 1200rpm. 30hp (@1200rpm) was the rating of the JP3, so definitely wrong here.

Makes me wonder if the plate is a fake!

I doubt its fake as firstly its not a pristine engine in a narrowboat by any means...I think the owner nearly fainted when he was told how much twin marine units go for over here!!...and the number matches on the flywheel. I do read Stationary Engine magazine and it seems that stamping issues with serial number plates are not uncommon so it might just be someone got it wrong. The RPM on this plate says 1200 so its quite a mystery! I do wonder if the HP rating is to do with how the HP was measured as I seem to recall that has changed over the years but again its also marked 18....

 

Its interesting from all the lists of serial numbers Ive seen that 1949 would start with a 7XXXX but that means the CS prefix and the side decompressors were odd...... Having said that I know full well that parts get changed over all the time on these engines so I might trust the serial number more than the parts so to speak.

[frangar]

This was sent to the Owner of said JP2 from a well regarded Lister person in the UK...Via the editor at Stationary Engine Magazine

 

Regarding Mr scarfe’s JP2 I answer as follows. The engine  number is a good one from my data book I date this 1949. I am sure Doreen Edgington could be more specific from the production records as to the exact month and who it was sold to. The JP2 was actually called 18-2 when introduced in 1929 which was the HP 18 and the number of cylinders 1. The range goes 9-1, 18-2, 27-3, 38-4 @1000rpm, however over the years there were improvements made and the speed was raised to 1200 rpm giving a continuous HP rating of 23. So the mystery is why does it show 30 HP on the plate, its bigger sister the JK2 would only give a continuous rating of 25 HP at 1200rpm. Well I can’t give you a categorical answer only offer some possibilities. The spec. gives 18-2 M suggesting that this could be a marine spec. as I can’t see the engine as a whole which could possibly give a clue. Is the engine painted an aluminium colour for a start? An interesting point my data book gives the engine max. gross BHP 31. Again I am not clear on what that actually is. The old BS649 1958 continuous rating , intermittent rating which is 10% more e.g. semi automotive use with a variable load dumpers loaders etc.  and is the same as the overload rating which is one hour at 10% overload in any 12 hour period. That was 1958 what the BS was in 1949 I couldn’t say. Remember the brake horsepower is that developed at the output shaft to the dynamometer brake by calculation from torque characteristics, speed etc.. There is the HP developed in the each cylinder, the indicator HP , deductions for driven auxiliaries , frictional HP and I could go on.. Furthermore Lister would produce the spec. to almost any customer requirement or even whim. Some countries may have regulation or tariff on imports of certain HP which manufactures had to try and get round. Finally was it an error while on the assembly track an apprentice stamped the number plate for a JP3 instead of JP2. I was apprentice once!!! So if Doreen can give the name of the customer might help and also let me have photo of the entire engine, not an answer but something to think about.

 

When I hear any more I shall update on here as it might be useful to others

 

 

 

[magnetman]

It's a JP2 with the HP rating of the JP3 inserted out of devilment to see if anyone noticed at the time. 

 

 

 

 

 

 

 

 

Edited December 8, 2020 by magnetman
Typo

[RLWP]

The only sure way is to saw it through and count the rings

[cuthound]

16 hours ago, magnetman said:

It's a JP2 with the HP rating of the JP3 inserted out of devilment to see if anyone noticed at the time. 

 

 

 

 

 

 

 

 

 

Maybe it is the rare high performance "GT" version? ??

[magnetman]

26 minutes ago, cuthound said:

 

Maybe it is the rare high performance "GT" version? ??

Nobody has asked if it has a Rootes blower on it.