Jowitt Poppit Valve Model Steam Engine
An usual engine, this is a Jowitt Poppit Valve Model Steam Engine. Made by Chelston Model Engineering in the
mid 1980s as a casting kit. Said to be based on a design by Samuel G Jowett from 1907. Cams on either side of
the crankshaft operate sprung 'poppit' valves for the inlet and exhaust.
The inlet valve was sticking badly and neither of the two valves were closing properly. So I disassembled the engine
which allowed me to run a reamer through holes that the valve rods run in. I also cleaned up the valves so that they
seated properly. Once it was put back together I reset the valve timing ensuring a clearance between the valve
follower and the cams when the valves were closed. An adaptor was made for the inlet port and the exhaust port
plug was sealed. I also made a slightly larger, heavier base for the engine. I am pleased to say that it now runs fine.
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