valve lapping problem

[Jennifer Edwards]

I just remembered what we used for lapping. It was called “Clover Valve Lapping Compound”. The stuff came in a small green tin with a press on lid at each end. One end contained Course grit paste the other end was Fine. It was made from carborundum powder and some kind of dark grey thin grease as a binder.

Also 1/32” is awfully thin for s good seal, that is only .030” if possible create a seat at least 1/8” which is about .125”. There is an order of magnitudes better seal with that small increase in width.

Have you checked for other issues like weak springs, sloppy valve guides not allowing a good seat, or the opposite binding the stem, not enough clearance on the rocker arm/tsppet, or some combination?

There may even be an issue from the piston side of the equation. Perhaps the lack of compression is leaky rings & etc...

Try static testing by blowing air into the cylinder and listening for where the pressure is leaking. It may not be the valves st all.

Jenny

 

[Brian Rupnow]

Thanks Bob. I did receive a set of plans for a mixer, and I see how the seat on the intake must be quite wide to seal compression and also to seal the mixer hole in the side of the seat. This is a very neat idea, and it does away with the requirement of an anti-backflow line in the gas line if the tank is below the carburetor. It looks like it would be difficult to bring a mixer down to the scale of an engine e with a 1" diameter piston and 3/8" diameter valves.---Brian

 

[blockmanjohn]

Brian, actually there is also an intake valve in the head which seals the compression. The mixer valve is only there to control the flow of fuel. John