Collection, Preservation and Display of Old Lawn Mowers
Can anyone tell me the pitch of the exhaust valve seat, on the 75 G 14 engine Model 10a . Mine needs to be re-cut due to pitting in the seat causing a poor seal and thus a compression leak!
Nominally 45 degrees. I say nominally as there is a convention to have a one degree difference between the angle of the valve and seat so looking at my Neway seat cutter that face is marked 46 degrees.
The seat face on your engine is cut directly into the cast iron block material and is relatively soft. If the engine has been sitting around in a damp atmosphere with the valve open it may be quite pitted and there is a danger that if you attempt to remove every last bit of pitting you may end up with an undesirably wide seat which is not conducive to good sealing.
The contact patch of the seat can be narrowed and “ moved” by the use of a 31 degree cutter at the top and a 15 degree one at the bottom but that is a councel of perfection , possibly not warranted for a humble Suffolk lump.
Many thanks yet again Wristpin, sound advice always.