Exhaust nut test

Made a new sample nut from high grade aluminium. My intention is to make a final version as soon as I get new, suitable insers for making inner thread (managed to damage the only one I got). Otherwise I will have to use this one and maybe make a somewhat larger dimension hole for the exhaust tube.

Exhaust Nut

Had to cut into the nut to get it loose. That does not matter since it is wery corroded and has to be replaced anyway. Thread is 20 TPI and I measured the outer diameter to 44.3 mm which I presume is  1¾ inch (44.45mm).

The new nut will be made from brass or brose. it will also be made for use with a hook wrench insted of a regular spanner.

At the same time I dismantled the valve gudes and destroyed my valve guide tool that was special made for another engine ..

Carb

I'm not sure the carb can be fixed. It's heavily corroded and I suspect the main jet can't be dismantled without destoying the threads or something worse.

Cheap fix

Since the Mark III engine was stuck, my fear was that the cylinder had been flooded with water and was a complete rust-disaster. At least the air filter was full of water...

Guess what, the rust was not that bad even if it is very worn and has some damages, it probably could be made to work. Only had to spray with penetrating oil and wait a couple of minutes to free the piston.

After some light grinding with 400 grit wet sand paper soaked with WD-40 (oil), the damages are clearly visible.

Annealed copper cylinder head gasket lightly sanded.

Amal 225/3

The carb for the Mark III is like no Amal I've seen before.
Wonder if it's possible to get spares if needed?
At least a visual inspection shows that the tickler is missing.

Newsflash

Got me another JAP engine project too as well as the Howard GEM Rotavator ( rototiller) it is attached to. The engine is a 600cc s.v. Mark III Type 5

Engine number is:
UCZ/Z
94433\5

If I'm correct that would be:
U = 600cc Side Valve Engine, 85.7 x 104mm bore and stroke
C = Sports Engine
Z = Dry sump Lubrication
Z = 1933 Model Year

U is a standrd 6hp (4½ hp nominal) engine, according to The JAP book so what with the C marking?

The JAP Engine Reference there are more alternatives and the Mark III engine is recognized as a Sports engine.

My hopes were that I could get it started. By lubricating with the famous Omega Omicron  636 penetrating oil. So far I have got the valve lifter, throttle and most other leavers and functions to work.

Unfortunately the next step is to dismantle the cylinder head to see how bad the cylinder and piston is since the engine is stuck.

Inspiration

Found a bunch of pictures on another blog. Obvious staged, the same chain-less Excelsior appear on many of the pictures with different drivers.

All together