---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Tue 01/17/06: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:16 PM - Cold weather starting and starter current (Andy Silvester) 2. 02:33 PM - Re: Welcome to the Jabiru Engines New-Look Forum! (Andy Silvester) ________________________________ Message 1 _____________________________________ Time: 02:16:13 PM PST US From: "Andy Silvester" Subject: JabiruEngine-List: Cold weather starting and starter current --> JabiruEngine-List message posted by: "Andy Silvester" At last week=92s Sebring Sport Aviation Expo, we endured a couple of very un-seasonably cold (for Florida!) mornings, and one or two of the many Jabiru-powered aircraft there were reporting cold-starting issues. All were eventually traced and fixed, but it=92s probably a good time to remind owners of the need for good connections and a low-resistance path for the starter current. Unlike other aircraft engines where the impulse-magneto retards the ignition for starting, the Jabiru has fixed-ignition so needs to be spun quickly to energize the ignition units (coils) for a reliable spark. Colder conditions will mean thicker oil (more engine friction), the fuel doesn=92t vaporize as readily in the carburetor and the battery=92s ability to deliver the necessary starter power is diminished. If the installation also has some short-comings, it can (and does) mean the difference between a good start and no-start at all. Here=92s some pointers, with apologies to those who already know this stuff: 1. On the initial turn-of-the key or press-of-the-button the starter will take almost 700 Amps from the battery. Once the engine is spinning on the starter, (i.e. after about 1 rev of the crank) the current drops to about 400 Amps. We recommend the Odyssey PC625 battery because it has a high level of CCA (cold cranking amps=3D625). Not many other types of battery will do this for the same size and weight. The thick orange cable attached to the starter is the right gauge to carry this starter current; if your ground / return from the engine to the battery is less diameter than this orange cable you will restrict the current when starting. For this reason, we carry this cable by the foot in our store as well as the appropriate swage-or-solder-on lugs. The connections of this starter and ground circuit are equally important; if the engine won=92t start after spinning it over, isolate the ignition and feel by hand the various connections at the battery / starter solenoid and the ground connection. If there is heat in a joint it needs either tightening or re-making. In the later Denso (silver) starter, any lack of tightness in the two retaining bolts means a poor ground-return. I admit I hadn=92t spotted this until last weekend; the starter has rubber seals between each of its major parts so it is clear that the bolts which secure it to the engine=92s backplate are carrying a large proportion of the starter current. Check tightness or even add an additional grounding strap from the starter=92s free-end to the engine mount plate. 2. Other ignition-related cold-starting issues are pretty well-known: check for spurious grounding of the ignition =91stop=92 leads (some call them P leads); both Pete and I have experienced issues with faulty ACS ignition switches. I remember stripping, cleaning and rebuilding one (watch for flying springs and contacts!) and solved the problem but they are not perfect. If you suspect the switch or leads to the coils, disconnect the leads at the coils and try restarting. If it starts OK, you know where to look but be prepared to stop the engine with the fuel shut-off! Spark plugs rarely give problems if gapped (0.022=94 =96 0.024=94) if they are un-fouled with lead and haven=92t previously been blasted-clean. Don=92t clean plugs, replace them. NGK=92s iridium DR9EIX gives longer life and (I=92m told by Jabiru) smoother running and response but I=92ve yet to try them. Coil gap with flywheel (magnet pole-faces) should be 0.010 but rarely needs adjusting unless disturbed. Condensation or carbon-dust from the central button inside the distributor cap(s) will cause ignition issues but fairly rarely. Change caps and rotors at 250 hours max. Spark plug leads last very well unless exposed to the elements as per an un-cowled installation (pusher, etc) or allowed to rub-thro=92 on the engine, so check them for cracking and/ or rubbing every 50-hours. 3. Fuel supply: the =91enrichening=92 or choke circuit in the carby won=92t work unless the throttle is closed fully. A high idle speed set by the throttle-stop screw has been known to hold-off the choke. The enrichener gets its fuel from the brass dip-tube which pulls fuel from a tiny jet at the bottom of its tube in the float-bowl. This jet can get clogged by debris or more likely the presence of water in the bowl which corrodes the aluminum and bits clog the jet. When you have the float bowl off, try blowing down the tube in the corner of the float bowl to check the jet. If you prefer a primer (I can see why you might!) use the nipple on the bottom of the carby next to the idle mixture adjusting screw; remove the blanking screw and attach the primer line. The idle-mixture air screw should be about 1 turn open. Richen the idle mixture by screwing it in, lean by opening. Adjust by no more than =BC turn at a time. Old fuel in the tank has lost some of its =91go=92 so try to ensure in cold weather you have a good fresh supply of gas. Avgas at 100 octane will start better in the cold than the same-age car-gas at 90-something. Give the engine a fighting chance by pulling the prop. through a few blades with the throttle closed, choke on and fuel boost pump on and switches OFF. This helps to reduce the friction in the engine and induces some fuel/air into cylinders. Especially when you might be frustrated and thinking hard about why your engine isn=92t starting BE SAFE and respect the propeller as if it=92s live unless you know for sure it isn=92t. Above all, don=92t keep spinning the engine on the starter hoping it will eventually fire; with a Jabiru, if it=92s not going in a couple of revs, then you=92re only adding to the problem by having a dead battery. Hope this helps, Andy Suncoast Sportplanes, Inc. 39248 South Ave. Zephyrhills, FL 33542 Tel: 813 779 2324 Fax: 813 779 2246 www.suncoastjabiru.com ________________________________ Message 2 _____________________________________ Time: 02:33:03 PM PST US Subject: JabiruEngine-List: Re: Welcome to the Jabiru Engines New-Look Forum! From: "Andy Silvester" --> JabiruEngine-List message posted by: "Andy Silvester" Lynn, I emailed you direct but now that this Matronics forum has a better interface and features I think there will be many more join the list. Andy Read this topic online here: http://forums.matronics.com/viewtopic.php?p=4783#4783