The Oil Tight Engine

[Charles P]

Tips on making a magneto engine as oil tight as possible would be appreciated.
No idea too simple or too stupid. 

Thanks


C

[Derek Sheldon]

I've had considerable success with the new silicon block crankcase gaskets

[Alan]

I've used those, with some success. I've not tried on a race engine, though - I usually don't use a gasket with them.
I'm just starting a rebuild of a mag engine, Charles, it might take some time because it's not a high priority one (i.e.,mine!) but I was wondering the best way to keep the oil in the crank pulley and magneto drive. We must be able to improve on felt seals.

[Charles P]

Crank pulley isn't an issue with a pressure fed engine.
The mag drive is a problem because in my examination the recess cast into the crankcase for the felt isn't exactly concentric with the shaft. My plan is to grind the mag shaft to have a surface for a lip seal but I'm still pondering how to rebush the non concentric housing.

Charles

[Alan]

Mine will be a splash fed with starting handle, but I don't think the crank pulley seal is a big issue, it's the mag drive one. Might have to get some machining done to ensure concentricity.

[leaf200]

I currently use a sealed bearing to seal the mag drive which seems to work.

I have tried a lip seal on the starter dog but it still seams to leak

[Charles P]

I solved the crank dog seal by forgoing a starting handle and having a blind bush.

[Alan]

Yes, that's what the Saloon is like, but I really want to keep the handle and the fan drive for this one.

One of the reasons starter dogs are hard to seal is the crank gear face does not always run true, so the dog doesn't either when it's tightened. You need to check with a dial gauge and correct if necessary.