Can someone answer this questions, = if the=20 timing is set at 25 degrees BTDC and the leading fires at 25 degrees = BTDC=20 and the Trailing fires 15 degrees later (10 degrees BTDC) - when = does the=20 third spark event fire, is that another 15 degrees with the = leading=20 firing again?

The pulley end keyway points = to 9.00 at=20 TDC ( plug sides) on the housing closest to the pulleys ( = Front/=20 our rear) - is this what is referred to as No1 housing?

George (down = under)

<snip>

In a message dated 04/26/2005 12:00 Central Daylight Time, = Lehanover=20 writes:

<< In a message dated 04/25/2005 07:00 Central Daylight = Time, jwvoto@itlnet.net = writes:

I can look into the spark plug hole and see the apex seal go = by, so are=20 you calling apex seal crossing leading plug TDC?

There are a number of gags to locate TDC close enough to get = the engine=20 to run.

(1)

Remove one spark plug from number one housing. Screw a length = of hose=20 into the plug hole. Put your tongue on the end of the hose. Gently = turn over=20 the engine. When you get a null, where there is no pressure and no = suction=20 on your tongue, that's TDC. Good to within a few degrees.

(2)

Or,

Bend up a piece of welding filler rod so as to make a pointer = that can=20 touch a flywheel (flexplate) tooth. Bolt or clamp the wire to the = rear=20 iron.

Take both plugs out of number two rotor housing.

Turn the engine until you see an apex seal in the center of the = trailing plug hole.

Bend the filler rod so that it points to the center of a = flywheel=20 tooth. Put a white paint drop on that tooth.

Turn the engine in the running direction, until that same apex = seal=20 appears in the center of the leading plug hole.

Put a paint drop on the tooth the rod is now pointing at. =

Count the teeth between the paint dots. Divide by 2.

The point half way between the two paint dots is TDC in the = number one=20 housing.

Good to within a few degrees.

Also, you can count the total number of teeth and divide that = number=20 into 360 to get the number of degrees per tooth. Paint the correct = tooth=20 yellow and make the rod a permanent piece, for setting accurate = timing in an=20 easy to see location.

(3)

Or,

(Similar to above)

Take both plugs out of number one.

Turn engine in running direction until an apex seal appears in = the=20 trailing plug hole.

Gently turn the engine backwards until an apex seal appears in = the=20 leading plug hole.

Half way between those two events is TDC. With practice, = accurate=20 enough to do by just feel and rocking back and forth by hand and to = find TDC=20 within a few degrees, or close enough to drop in the distributor and = have=20 the engine fire instantly and run fine.

(4)

If you used grease or Vaseline on the side seals, you can have = a plug=20 prepared with the center knocked out of it and a plug in place with = a piece=20 of brake line soldered through the center. Screw this special plug = into the=20 bottom plug hole. Push a length of plastic tubing over the piece of = brake=20 tubing. Pour auto trans fluid through the top plug hole. Reinstall = the top=20 plug. Hold the hose in the vertical. Turn the engine until the fluid = level=20 nulls.

That's TDC number one with a degree.

(5)

The flywheel end counter weight is centered between the plugs = on number=20 two rotor housing. That's TDC number one within about 10 degrees. = But you=20 can get good at it, and get more accurate.

(6)

If you have the front pulley bolt and washer off, looking from = the=20 front

pulley end,

the keyway in the 9:00 O'clock position is TDC number one = within a few=20

degrees.

My TDC rig is for setting up port timings and requires a = disassembled=20

engine, so that won't help you. Good for inside of one degree. =

(6)

Quick and dirty.

Take out either plug from number one housing.

Wet a finger. Hold it gently over the empty plug hole. Turn the = engine=20 in

the running direction. When the air quits pushing past your = finger,=20 that's TDC

within 10 degrees or less.

Lynn E. Hanover

<snip>

On 9/19/07, bmears9413@aol.com <bmears9413@aol.com> = wrote:=20

Changing=20 the subject a bit, I want to make sure i have my motor on TDC to = set my=20 timing marks on the flywheel. This is my plan, tell me what you = think. I'm=20 building a fitting to screw in the spark plug hole, and running a = vacuum=20 line to a small suringe (like a insulin suringe). I can eyeball = the rotor=20 location close to TDC, the install this contraption and rotate the = motor=20 so the suringe moves out to the end and starts back in. then back = the=20 motor up again till the suringe tops out. I figure that outa be = and=20 accurate TDC. Whadda ya think???

Bob Mears
Supermarine=20 Spitfire

-----Original Message-----
From: Ed = Anderson <eanderson@carolina.rr.com=20 >
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent:=20 Wed, 19 Sep 2007 1:16 pm
Subject: [FlyRotary] Re: Strange = Ignition?=20

I do not believe that is a significant = factor,=20 either, Al. After all, we're suppose to do our ignition = checks on=20 the ground before take off {:>). My understanding is that = best=20 power on the 13B has ignition timing between 25-28 deg BTDC, so = not=20 surprising that the 20B would fall in that range also. = Sounds=20 reasonable to me.

Ed

----- Original Message ----- =

From: Al = Gietzen=20

To: Rotary motors in = aircraft=20

Sent: Wednesday, = September 19, 2007=20 3:08 PM

Subject: [FlyRotary] Re: = Strange=20 Ignition?

I = wondered if=20 perhaps one issue was that I was doing the ignition check = static, on the=20 ground; where the combination of RPM and MAP would be different = than in=20 the air. But on checking with Tracy 's = spreadsheet on the timing settings, over a fairly broad range = above=20 about 4900 the timing is (should be) in the range of 26 to 28 = degrees=20 BTDC.

Al

Email and AIM finally together. You've gotta check out free AOL = Mail!

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