# Another Poppet Valve Design



## cfellows (Dec 7, 2007)

Here's another variation of a single poppet valve that provides both Inlet and exhaust with one valve. This configuration will work with cam configurations giving 1, 2, 4 or any number of cycles between power strokes.

The poppet valve is actuated by a piston valve which normally allows air to exhaust from the cylinder as long as the cam isn't pushing against it. As the cam begins to press against the push rod, the piston valve is pushed up past the exhaust port to close it off. The poppet valve stem is inserted into a hole in the piston valve with enough clearance at the bottom that the poppet valve will not open until the exhaust port is completely closed. Further movement of the piston valve causes the valve stem to bottom out and then open. High pressure air is then admitted to the piston for a power stroke. 

Near the end of the power stroke, the piston valve is allowed to drop back down, closing the poppet valve and opening up the exhaust port. 

I have an engine that uses this valve arrangement in a 4 stroke (power stroke every other rev) and will post pictures later today.


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## Bogstandard (Dec 7, 2007)

Another nice design there Chuck.
As I have been playing around with it I have noticed that it is a very versatile air delivery system, and the combinations seems endless, but it sure is touchy on timing, it has to be spot on, and you do need a fine tuning bit in the link.
Do you find this with your engines?

John


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## cfellows (Dec 7, 2007)

John,

I've never messed around with the timing too much. I always set the valve to open at or slightly after TDC. 

Chuck


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## Bogstandard (Dec 9, 2007)

Chuck,
It might be because I also have adjustment for the length of time it fires, I have been firing just after TDC and stopping at just before BDC. This may be the cause of my problem.
I can see now why you are trying to find a quick fire method for cams, as in a firing pin.

John


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