No announcement yet.

Low compression picture

  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    I'd ask the same questions as J.Tiers: does it run, not start, or what? These little engines can be much worse with high compression than low, in some cases. One well-known model builder reported that one of his older engines, built 10+ years ago, was always tempermental. Hard starting, kick back on you while cranking, jump all over the place while running, etc. He lowered the C.R. (don't remember what he did exactly) and it's a different engine. I'd surely try running it, getting the ring(s) seated, etc. before modifying the C.R.

    We learned a hard lesson on our first engine project: there must be NO excessive friction in any part of it, or it simply will not run. Don't think that "it'll wear in", it won't.


    • #17
      I built my Bob Shores Eagle hit and miss with 5:1 compression. I wish I would have gone with a little less. The idea with the low compression is to get the engine to "idle" very slowly to sound more like a full sized hit and miss. When mine fires it still does so with a lot of power even at 5:1