Ian, Thank you so much for the very exhaustive reply. Even I am able to grasp the logic behind your suggestion no 2. The stuck impulse coupling would keep retarding/delaying the ignition from the required minus 30 all the way to zero obviously fouling the higher revs. I am going to look into this immediately.
Best regards Jarek On Mon, 14 Oct 2019 at 23:47, Ian Williams <[email protected]> wrote: > Hi Jarek, > > I hope to be of some help to you based in issues I have had in the past > with Limbach 2L engines. > > They are a great little engine and if looked after will perform well for > years. I currently “look after” ie the engineer for 3 aircraft wit hL200’s > and one with an L2400. > > 1. Here in New Zealand we need to remove the Magneto every 2 years or > 250hrs … which ever comes first and any issues with the magneto are found > (usually) However sometimes not the case. The L2000 on our Dimona was ex > Thai air force and the engine was not used for 20 or so years. It did > around 150 hrs of trouble free running then without warning, the condenser > in the Magneto broke down. Fortunately just after take off so a return > landing was possible. Interestingly, it broke down less than 1 hr’s running > AFTER a bench check. … so a problem COULD be a faulty condenser … though > if that was the case the engine wouldn’t idle either. > 2. What is possible (and has happened to me) is an issue with the > impulse spring … The impulse used is a standard GA one. Usually they > are internal of the engine (ie Lycoming etc) hence well oiled. The Limbach > one is external and hence needs external lubrication. There is a little > oil pot on top of the rear case to do that but is really quite hit and > miss. We had a problem (which fits to your situation) where the spring > was quite “dry” and would not release. … ie “bound up” Hence the engine > would run OK at low RPM’s but no good at high. The fix was to take the > magneto out (again) dismantle the impulse, give it a good clean and > lubrication and reassemble .. then back on the Aircraft. The problem was > solved. > > Just a point re advance and retard … Not a lot of point in that > automatically adjusting with an engine that runs at a fairly constant RPM … > the KISS principal here. > > However the old De Havilland Gypsy engine had a mechanical system which > moved the magneto physically when the throttle was closed … for a better > idle. A friend of mine put an adjusting ignition(ie replaced one magneto) > system on his 150hl lycoming The idle was significantly smoother. > > > > So I think your problem is no 2 > > > > Best regards > > Ian Williams > > Drury > > Auckland > > New Zealand > > > > ZK-GCB (Dimona) > > ZK-GOC (Grob 109 with a 2400 Limbach) > > ZK-GNW (Grob 109 2000 Limbach > > Working on another Dimona … to be ZK-GCD (ex VH-GNW) > > > > > > *From:* [email protected] *On Behalf Of *Jarek Steliga > *Sent:* Monday, 14 October 2019 8:40 p.m. > *To:* [email protected] > *Subject:* Re: [DOG mailing list] ignition advancement not affected by > the RPMs > > > > Ric, Ian, > > > > Thank you very much. The idea of there being no advance seems bizarre for > someone having only to do with 'terrestrial' engines :-) > > > > On Mon, 14 Oct 2019 at 08:07, Ric Sutton <[email protected]> wrote: > > Hi jarek > > Yep you are correct, there is no advance. It stays the same throughout the > rev range. > > > > *From:* [email protected] [mailto:[email protected]] *On > Behalf Of *Jarek Steliga > *Sent:* Sunday, 13 October 2019 5:17 PM > *To:* [email protected] > *Subject:* [DOG mailing list] ignition advancement not affected by the > RPMs > > > > > > > > Hello, > > > > Can someone please confirm that once my L2000 starts with a 43 series > Slick magneto mounted, the ignition advancement will stay the same (30%) > throughout the whole RPMs range? In other words as I understand in this > system there is no spark advance mechanism installed apart from the impulse > coupling which only affects (delays/retards) the spark timing up until 400 > RPMs (i.e. well before the engine kicks in). > > > > > > Thank you in anticipation > > > > Jarek > > > > > >
