| Gallery, Projects and General > Project Logs |
| Webster IC Engine build log. |
| << < (22/69) > >> |
| Bogstandard:
Chris, Now you are starting to slow down a bit and take your time, it is very noticeable in your work. Compared to your earlier builds, this one is exceptional. Keep it up. Bogs |
| raynerd:
Thanks John! I`m still struggling to find data for the groove width and depth on this piston for the piston ring! The table that was posted would have been perfect only it doesn`t include a 3/32" cross section! I`ll have to try and work it out based on that data unless anyone can lend me a hand! Chris |
| NickG:
Chris, As Doug said, I believe the ring is technically supposed to roll slightly in the groove so it pushes against the groove wall and seals. This is maybe to get the lowest friction. I don't know whether the groove dia is supposed to be size for size or slightly larger than the id of the o ring. I would think, like you it's supposed to be marginally larger. Might be worth checking if Marv has a program for this? Nick |
| Bogstandard:
Chris, Whenever I fitted o-rings as piston rings I looked at them in a slightly different way, in that I didn't want them rolling up and down in a wide slot. To me that stinks of maybe getting twisted up and uneven wear. My way for a 3/32" (0.094") cross section ring would be to just cut a square section slot a couple of thou wider and the same shallower. So 0.096/7" wide by 0.091/2" deep. That way, the ring, by being pushed into the groove, would take up an oval shape, giving a nice side pressure to form the seal. As the ring wore away, it would slowly form a flat where it rubs on the cylinder wall and gradually return to it's original round shape. Your bore does need to be rather smooth, otherwise it will wear away an o-ring fairly quickly. I am sure that other people have different views on the subject, I just told you mine that worked for me. John |
| dbvandy:
I agree with Bogs... The fitment of the o-ring is important, but not critical.... from all the information I read on the subject, the important thing is that you have pressure on the dynamic surface (cylinder) at all times. The engine is very low compression, about 4 to 1 where a car is about 10 to 1, so you are not going to get much blow-by either way. Jan Ridder does not even use o-rings in his engines, just a tight fit. It is starting to look like something now! I love that feeling! Have you decided on ignition? If I had seen this, I would have done it without a doubt... http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=13767 This CDI unit will make for a really clean install. You still have to lug around a battery, but it will make a reliable spark. Or you can go the route I did with the trimmer coil as it works beautifully and does not need anything else to run. On the Otto, I used some neo magnets on the flywheel, so you don't have to use the finned flywheel from the trimmer. Just some food for thought.... Doug. |
| Navigation |
| Message Index |
| Next page |
| Previous page |