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| Jan Ridders Otto 4 stroke build |
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| NickG:
Dave, I think that was the way it was done on my Escort RS Turbo. Apparently you could freeze the pin to reassemble too but when I rebuilt the engine I just got someone to press them in! Doug, that is fantastic, another good example of the ignition I've been wondering about for so long. Well done :bow: Can't wait to see more You certainly don't mess around either! Nick |
| dbvandy:
Thanks for all the kind words, guys, I really love doing this, so the time spent pays big dividends in my sanity column. The motor is running really good and smooth now, I will have some good vids and pic tonight. Hopefully the lighters will be in today's mail and I can get started on that this weekend. More to come... Doug |
| dbvandy:
Well, I spent a few minutes tweaking the motor today. No new parts, just a timing wheel made from a 360 deg protractor. Here are some videos: The Engine running about 2500 RPM. Being as there is no real throttle to control RPM, you control it through mixture. Richer runs cooler and slower, lean runs hotter and faster. One issue with the vapor carb is that this is a moving target as the powerful hydrocarbons vaporize first and so you have to add a ton of air, then what is left is less volatile and you have to adjust it with less air bypass to enrich the mixture. I used a smaller and lighter flywheel (5 inches) than the plans called for because this is about all my 7x12 can turn. Maybe when the cam timing is better and the ignition more reliable, I can get it slower, but this is about it for now. The old timing light I have pops ghost images, but the timing is pretty close to 10 degrees BTDC. I did not have the timing wheel when I shot this, so I will use it when I fine tune the ignition timing. After 20 minutes and 2 tanks of Coleman fuel with a few drops of Marvel Mystery Oil, the cylinder only got up to 190 degrees and the head only up to 145. I do not see it being run much harder than this, so that is about my benchmark for temp. Then she ran out of gas.... The coil was mounted with the old bracket from when I had the coil mounted fixed to the Webster base. If it becomes a permanent part, I will make a more elegant mounting system. Timing is changed by rotating the position of the flywheel and the new 1/4-20 setscrews hold it very well. Right now it HAS to be clamped tight to the table because the flywheel is way out of balance from the addition of the magnets. I might epoxy some washers 180 degrees to balance it. The Vapor tank is a transplant from the Webster. It ran good, so I just wanted as few variables as possible to get it running smooth. The tank for this engine will be made when my rotary table arrives. The intake valve seem to be floating a bit causing it to stay open and blow fuel out of the tank. I later deduced was exhaust timing closing too early and creating pressure in the cylinder, then the intake opened and the pressure went into the tank, spewing fuel. But, I had some stronger springs, so I put them on just to make sure. The other ones seemed a bit week. The Marvel mystery oil does not burn so it just collects in the cylinder. This is a good thing. Once it is broken in I will reduce the mixture as even now it does not smoke when running. The smoke you see in the videos is from 3and1 oil used to lube the valves and cams. There is a little burnt oil and carbon on the exhaust side as to be expected when it is so oil rich. This is after about an hour of running and 10 tanks. Still on the fence when it comes to the piezo ignition. I might see if I can tuck this coil in under the cam in a tasteful way. I do not know if it will deliver a reliable spark at cam RPM, so it might have to stay on the flywheel. Maybe if I paint the lamination silver or something... More to come... |
| NickG:
Great analysis Doug, love it. It runs so well now, sounds like much larger stationary engines. Nick |
| madjackghengis:
From the way it runs, Doug, I'd think about making an actual carburetor with fixed jets and actual fuel control, so as to get the full range of rpms. You might inset the magnets into the flywheel, rather than leave them outside, and thus need less work to balance it out. The key is the magnets switching the flux precisely at the same time each time, and that is controlled by their placement, which being fixed, means it should be possible to put a key in the flywheel once the timing is perfected. You definitely need to have valve overlap if you're going to run it at any significant speed, to avoid the pressure build up you speak of. I've got a copy of Jerry Howell's carburetor he designed for small engines, as part of my radial engine plans, and his carburetor will give good control and has an idle jet and all, basically a real and complete carburetor, and not too complicated. :bugeye: you've definitely got her down to just working out the last little bugs, fine job, all the way. :headbang: cheers, Jack |
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