After 52 Hours at a correctional facility the Sizaire crank has decided to go straight or I certainly hope so and after a week of doing penance planting trees, spraying weeds and other domestic deeds I have earned my pass to the shed.

The reassembly was straight forward the install was done as a unit by pulling it up through the bottom and all the lines connected with no problems. Now it has to be remembered that the car was running when I pulled it down so I was somewhat surprised when she kicked back on startup and would not run.

It seems that for the whole trip from Perth to Sydney the valve timing was one tooth out so I retimed the starting timer and the magneto so all should be good now. Well nearly, everytime I tried to crank it the starting dog slipped at compression, easily fixed by reforming the teeth with the angle grinder but what was the chance that she lasted exactly until the end of the trip but no more.

One pull on the crank and she started and at exactly the same time it started pouring with rain so a quick wet trip around the shed seems to confirm that she runs, will have to leave it until tomorrow for a proper test.

Not a mysterious eastern technique involving staring at a blank wall and emptying your mind, no instead I have been staring at the inside of the Sizaire crankcase trying to fill my mind with the ancient French methods of crankcase breathing.

Single and twin cylinder engines have problems with the huge pressure spikes in the crankcase causing loss of power and oil leaks and probably other things that I have no idea about. Generally old engines have lots of vents to handle these spikes and oil leaks were just a way of keeping the dust down.

The Siz has two vents with one way leather flapper valves attached, one allows air out but not in and the other works in the other direction sucking in air and more importantly oil out a reservoir that catches the leaks from the rear main so it works like a scavenging pump, this one has never worked.

So on my car, instead of the oil being sucked back inside the engine it is sprayed over the entire underside so no drip tray is big enough for this car.

In the last picture you can see Colin has recessed the area where the valve is going as there was not enough clearance due to mods done by others.

The question is if I use leather, what type or is there a synthetic that would work better?

Suction Flapper Inside Crankcase

Location of out going flapper, recessed due to clearance problems with flywheel