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| Another version of how not to build a model engine |
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| NickG:
Another strange phenomonen. I know I keep banging on about Jan Ridders engines, but this is because he has build a lot and done a build log of his findings with all of them. I noticed on a couple of his engines he has some sort of additional chamber with check valves in line. Not quite sure why they are needed without reading through it again but they are! Nick |
| sorveltaja:
Well, the unlucky sparking plug saga continues.. Any spark plug, that I've made, doesn't seem to last in use. I have considered purchasing commercial ones, as they have ceramic insulation. Smallest size available here is NGK CM-6. Anyways, I suspect, that 12V/2.5A, that my current power supply gives, isn't enough, causing sooty contamination. |
| jim:
CM-6 are 10mm thread, NGK do spark plugs down to M8 thread, don't know how long they are though :scratch: |
| sorveltaja:
In the meantime, I took the ignition system under inspection. Especially the ignition cam caught my eye (finally). The flat part seems to be too large, as it causes two sparks. First being weaker one, when the ignition points close, and second being the desired one, when the points open. So I turned the ignition cam's diameter ~0.5mm(~0.019") smaller, thus making the flat part smaller also, just to see, does it have any effect on that double sparking -problem. Shame on me, as it might be too hasty to tell any results yet :wack:. But it seems, that faster close/open sequence works better. Earlier, same amount of test running got the spark plug(s) sooted badly. Now the plug stays cleaner anyway, for some reason :scratch:. |
| Bernd:
S, Wouldn't a lobe like on a car engine cam work better that a flat spot? Just wondering out loud. :scratch: Bernd |
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