- Joined
- Jan 17, 2009
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I built the Phil Dulcos 6 strokes hit and miss.
I am having problems with the missing action.
The engine runs well with the hit&miss mechanism disabled. Runs fast and is not overly touchy on the needle.
Spark is at TDC.
The engine has run full power for about 1/2 hour.
Has bounce but if rotated slowly does loose compression.
The hit&miss mechanism is free an works well with no binding, if I make it miss manually at a very low duty cycle i.e. short miss time and long recovery time it works as expected but if the RPM is allowed to drop where it should be it will not speed back up
to the full speed. If I run it with the drill at full speed it stays there, but if I just get it popping it slowly decay to a stop.
Calculating the compression ratio is a bit complicated because there are several dead volumes on the valve ports but it it is around 7.5 calculated, from what I read is probably on the too high side.
The distance from the combustion chamber to the spark plug electrode is 0.32", in other words the spark is at the end of a cylinder cavity 0.32"long 10mm in dia.
Any comment on what can be done to make it hit&miss with a nice low duty cycle is appreciated?
(technically is already missing 1/3 of the cycles by design)
I am having problems with the missing action.
The engine runs well with the hit&miss mechanism disabled. Runs fast and is not overly touchy on the needle.
Spark is at TDC.
The engine has run full power for about 1/2 hour.
Has bounce but if rotated slowly does loose compression.
The hit&miss mechanism is free an works well with no binding, if I make it miss manually at a very low duty cycle i.e. short miss time and long recovery time it works as expected but if the RPM is allowed to drop where it should be it will not speed back up
to the full speed. If I run it with the drill at full speed it stays there, but if I just get it popping it slowly decay to a stop.
Calculating the compression ratio is a bit complicated because there are several dead volumes on the valve ports but it it is around 7.5 calculated, from what I read is probably on the too high side.
The distance from the combustion chamber to the spark plug electrode is 0.32", in other words the spark is at the end of a cylinder cavity 0.32"long 10mm in dia.
Any comment on what can be done to make it hit&miss with a nice low duty cycle is appreciated?
(technically is already missing 1/3 of the cycles by design)
