The 918 side valve engine was available in several versions, the original engine was used in the Morris 8 and there was a marine version, the Vedette, shown in the photos.The engine was re-designed as type USHM2 for the Series MM and later re-designed again as type USHM3 for the later Series MM. The differences are listed on the website under Car Ident, Engines.
U = 8 HP power rating, S/P = side valve/push rod OHV, H = engine type designation, M/W = Morris/Wolseley
There were also versions for the President Tractor and the overhead valve version in the Wolseley 8, UPHW.
In addition th engine was used as an auxillary engine in the Centurion tank and several of these, including mine, have been adapted for use in the Series MM. See website, Tech. Info, ex WD Engines.
Your engine seems to be a mixture of one type of block with a different cylinder head. If you can find the brass plaque it will identify the block.
Note. The bolt threads on the engine are Metric Fine and the bolt heads are Whitworth.
Ref head bolts, there are still original studs on the centre row.
After a lot of search on the Internet and in local shops here in Cyprus I have finally found this antifreeze
As I read in the Morris Minor Operational Manual, I must top up when the cooling system is at its normal running temperature, in order to avoid loosing antifreeze due to expansion. How much quantity of antifreeze should I add in the radiator?
About 25% should stop corrosion of any alloy parts.
If you drain the radiator, add about 4 pints of antifreeze, add water to the bottom of the header tank and run the engine to mix then top te radiator up to its normal level.
Personally I just slop some neat antifreeze in the radiator every time it needs topping up
What is the difference between the "USHM2" and the "USHM3" cylinder head?
I have a spare head, but also a not running complete engine.
This cylinder head is a little bit different as the one on the picture.
They told me he has an internal water leak, when I find a complete one, I have more spare parts.
The USHM2 head had no thermostat housing and the dynamo bracket was attached to the head. The USHM3 head had a thermostat housing and no dynamo bracket, which was attached to the water jacket. Go to the Series MM website http://seriesmm.mmoc.org.uk Click on Car Ident and scroll down to Engine Information. If you read all of the website there is a lot of useful information