I have just got the the cutting metal stage with this project. This will be my first complete engine although I have made a lot of bits for old engines over the years.
I have had the original drawing for a while but didn't feel good about it so I decided to do a 3D model (SolidWorks) to get a feel for the task. I nearly always do this for anything I plan to make. Of course I couldn't resist tinkering. I wanted to work in real metric for a start so I have been going throught the design converting it to metric and while I was at it I made a few "improvements":-
- I have added a couple of orings to the front housing and the backplate interfaces to simplify the sealing.
- I have added a ballrace to the crankshaft - it is a bit small and I may find a larger one later. - I will probably also make the engine plain bearing initially and add the bearing later once the engine is proved.
- Changed the cooling fin shape, the number of fins and the head shape.
- balanced the crankshaft.
- lengthened the bottom of the cylinder to reduce the volume of the crankcase to improve the pumping.
There may yet be other things that happen as I do the drawings.
I do have some questions, mostly general ones about the timing of these small Diesel engines
One thing in particular I find confusing on the drawings of the original engine is the reference on the timing diagram of sub piston induction. As you can see from the image4.jpg the piston skirt never opens the exhaust to allow air to be drawn into the case so I wondered if there was an intention to knotch the bottom of the piston to create sub piston induction that had not found its way onto the drawings.
