After talking with Wayne last week, we decided that something was wrong with cylinder #4. We thought that a ring was probably broken but…
This is what I found. No broken ring ! 😊 But there was something else Wayne noticed. Above you see the new piston left and old one right.
The oil ring normally is a split ring with holes behind it. This is good for normal engines with the cylinders pointing up (normal in cars). But with engines with opposing cylinders and radial engines you need more oil “catching” as there is more oil splashing around. With my old piston (right) this is done with a big grove under the oil ring, and lots of holes. When the engine is running, the oil on the cylinder wall gets scraped off and “drips” back into the piston and then gets thrown back inside the engine.
With my new piston’s that extra oil catching mechanism is not there.
This means that
- There is oil getting into the combustion chamber, and that’s not helping the combustion.
- The film of oil prevents the rings from bedding in, as there isn’t good contact. This means the rings won’t seal as well as they could.
- Plus I also might have gabs in my rings that are possibly a little too wide.
So I am going to make a little modification to my two bottom cylinders, #3 and #4.
And re-check the ring gabs 🙂