Today's Message Index:
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1. 09:28 AM - Re: Cold weather starting and starter current (lgingell)
2. 10:10 AM - Re: Cold weather starting and starter current (Andy Silvester)
3. 11:30 AM - Re: Re: Cold weather starting and starter current (Lynn Matteson)
Message 1
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| Subject: | Re: Cold weather starting and starter current |
--> JabiruEngine-List message posted by: "lgingell" <lgingell@matrix-logic.com>
The =92 and =91 are replacements for the " marks (quotes). I suspect Andy composed
this in Microsoft Word, and pasted it in. Word (and many other applications)
take the straight quotes " and turn them into 66's and 99's to make it "proper".
There's a few other ones in there that I couldn't guess!
Cheers,
..lance
--------
Zodiac XL/Jab 3300
http://lancegingell.com/plane.asp
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=5266#5266
Message 2
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| Subject: | Re: Cold weather starting and starter current |
--> JabiruEngine-List message posted by: "Andy Silvester" <info@suncoastjabiru.com>
Sorry about the spurious characters; I must make sure to compose the message here
and not in Word in future! Here's (hopefully) the cleaned-up version (I can't
get the line lengths consistent!):
At last week's 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 its 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't vaporize as readily in
the carburetor and the battery's 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's 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=625). 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't 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't 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's backplate are carrying a large proportion of the
starter current. Check tightness or even add an additional grounding strap from
the starter's 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 'stop' 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" - 0.024") if they are un-fouled with lead
and haven't previously been blasted-clean. Don't clean plugs, replace them. NGK's
iridium DR9EIX gives longer life and (I'm told by Jabiru) smoother running
and response but I've 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' on the engine, so check
them for cracking and/ or rubbing every 50-hours.
3. Fuel supply: the 'enrichening' or choke circuit in the carby won't
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 out, lean by closing. Adjust by no more than 1/4 turn
at a time. Old fuel in the tank has lost some of its 'go' 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't
starting BE SAFE and respect the propeller as if it's live unless you know
for sure it isn't.
Above all, don't keep spinning the engine on the starter hoping it will
eventually fire; with a Jabiru, if its not going in a couple of revs, then
you're only adding to the problem by having a dead battery.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=5277#5277
Message 3
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| Subject: | Re: Cold weather starting and starter current |
--> JabiruEngine-List message posted by: Lynn Matteson <lynnmatt@jps.net>
Andy, when you originally sent this, on Jan 17, I got it perfectly. But
there was a second posting that came through with the goofy punctuation
marks (a neighbor who saw it said it was HTML encoded). Has this
anything to do with the Matronics vs. Yahoo thing?
Lynn
On Thursday, January 19, 2006, at 01:10 PM, Andy Silvester wrote:
> --> JabiruEngine-List message posted by: "Andy Silvester"
> <info@suncoastjabiru.com>
>
> Sorry about the spurious characters; I must make sure to compose the
> message here and not in Word in future! Here's (hopefully) the
> cleaned-up version (I can't get the line lengths consistent!):
>
(original deleted by Lynn to save space)
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