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  1. f2cf1g

    Peggy - my Holly Buddy remix - 2.5cc CI engine

    Well done. Did you make a new piston?
  2. f2cf1g

    Peggy - my Holly Buddy remix - 2.5cc CI engine

    Yes, but I only heat once and let it cool, then re-lap. I have never found any problem with the pin fit afterwards, though I suppose if it was retained with a light interference fit it might become noticeably looser which might have to be dealt with. Roy
  3. f2cf1g

    Peggy - my Holly Buddy remix - 2.5cc CI engine

    Rather than make new, why not try "cherry-bombing" the piston and contra to make swell a bit? Often works for me.
  4. f2cf1g

    Nalon Viper 2.5cc CI Engine

    Hi Pat. I'm following your thread with interest because I'm also building one. My scrap bin is far from empty! The drawings show two methods for cutting the transfer ports, the one you are contemplating and another with the flute extending from a hole drilled at rightangles into the bore. I...
  5. f2cf1g

    First Running Engine

    I'm a control line and free flight man too, don't know much about throttles! What I've found in doing Nelson glow head conversions is that getting the compression ratio right can be difficult and often takes a bit of experimentation. When it's in the right ball-park, setting the needle...
  6. f2cf1g

    First Running Engine

    Well done on getting it running, it sounds strong, revs sound OK to me. The motor is on the boundary between 2 and 4-stroking in the second video. If you can lean it out to pure 2-stroking, the compression ratio is OK (though you might get more power by increasing it). If it won't 2-stroke...
  7. f2cf1g

    First Running Engine

    You have described the classic symptoms of an under-compressed glow engine, i.e. stops when plug disconnected and unwilling to 2-stroke. Try skimming the head 0
  8. f2cf1g

    SuperTigre G15 engine resurection!

    Can I ask what was wrong with the original piston/liner set? Only running will wear it out, not sitting in a box. I doubt that it's clapped out sufficient to stop it running or pulling a combat model round at 75mph. The process of enlarging a cast iron piston is often called "cherry bombing"...
  9. f2cf1g

    My First Engine Build

    Those things are no use for the tolerances applicable to pistons and liners. To have any hope of measuring taper accurately you need a bore gauge. However, that's not necessary provided you follow Ken's advice and lap the liner and the piston using the techniques described on Ron's site. I...
  10. f2cf1g

    My First Engine Build

    After you mentioned it in your last post I watched your video (not sure why I didn't see it before). The motor appears to be oscillating not fully rotating. I've not seen this on a glow before but in a diesel it is caused either by too high compression ratio or too much fuel causing too much...
  11. f2cf1g

    My First Engine Build

    If you suspect the piston seal (it should hold compression for several seconds when held at the top of stroke) and if the piston is made of cast iron you can make it fit more tightly by "cherry bombing". First expand the piston by heating with a gas torch until it is glowing bright red then...
  12. f2cf1g

    My First Engine Build

    I'm sorry to hear that you have no success but it must be fixable, just have to find the cause. For example, I have recently completed an Atom Minor. Initially it wouldn't start without an electric starter, the symptoms were exactly as you describe. I suspected the piston fit which was rather...
  13. f2cf1g

    My First Engine Build

    The motor sounds good and I'm sure is ready to run. However, 8.3:1 is low and may well be the problem whatever the designer says. Don't forget that the teflon and aluminium washers are both reducing the compression ratio. We are talking tenths of a mm here. No need for a new head, just put...
  14. f2cf1g

    My First Engine Build

    Hi c_mario and forum, I haven't posted before. Apologies if I have contravened forum etiquette by posting here first. I see you have re-made most of the motor without success and it occurred to me the one thing you haven't tried changing is the compression ratio. I have done a few Nelson head...
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