[Auburntsts]

On my IO-540 my left mag is a Slick retard breaker paired with a SlickStart. I know that with the left mag selected and the start switch activated (I removed the power lead to the starter, purge valve and mixture at ICO) that the SlickStart buzzes which indicates it is functional. Is there a procedure to verify that the retard breaker is properly functioning without removing the mag from the engine?

 

[BobTurner]

Sure. Just put a standard timing box ("buzz box") on the left mag. You should see/hear the points open near TDC when rotating the prop in the normal direction. Just after they open, stop, turn the prop backwards 30 deg, then go forward. See/hear normal point opening at 25 deg BTDC. You'll need the ignition switch on, at least left side.

 

[paul330]

The retard breaker is timed internally in the mag relative to the normal breaker - there is nothing you can do to adjust it. Just time both mags and leave it at that. I certainly wouldn't mess about turning props with an ignition live no matter what precautions I took.......

 

[stamper]

I think that is why you want to have the wires off the spark plugs when you do any timing at all

 

[Auburntsts]

The retard breaker is timed internally in the mag relative to the normal breaker - there is nothing you can do to adjust it. Just time both mags and leave it at that.

I'm not trying to adjust anything. I'm trying to verify it is functioning properly in conjunction with the SlickStart.

I certainly wouldn't mess about turning props with an ignition live no matter what precautions I took.......

Really? IMO it's no more dangerous with the starter disconnected than when normally timing the engine as long as you take the proper precautions. YMMV...

 

[Jesse]

If it starts well, it's working. The real test is a hot start after sitting on the ramp for about 20 minutes so the cowl is heat soaked.

 

[Auburntsts]

Sure. Just put a standard timing box ("buzz box") on the left mag. You should see/hear the points open near TDC when rotating the prop in the normal direction. Just after they open, stop, turn the prop backwards 30 deg, then go forward. See/hear normal point opening at 25 deg BTDC. You'll need the ignition switch on, at least left side.

Just to make sure I got this: With the left mag on and the starter switch engaged so the SlickStart is drawing power, the mag should fire closer to TDC than normal timing (as verified by the mag timer) and if I release the starter switch and continue rotating the prop the next time it fires the timing should have advanced back to 25 deg BTDC?

 

[BobTurner]

NO! Do not engage the starter. Master off! As others have said, take common sense precautions against an accidental start. At tbe least, fuel and mixture off, and stay out of the prop arc. Better yet, pull a plug from each cylinder.
Just slowly pull the prop thru by hand, ignition on left, buzz box on. It should show points opening near TDC (markings on flywheel are for cylinder #1). Just after you pass TDC, turn the prop backwards 30 deg (this will keep the retard coupling released), then go forward. Buzz box should sound at 25 deg BTDC as shown on flywheel.
In operation centrifugal forces release the retard coupling above some rpm, but you'll never spin it that fast by hand. Hence the 'go past TDC, backup 30 deg, go forward' method to release the coupling.

 

[Auburntsts]

NO! Do not engage the starter. Master off! As others have said, take common sense precautions against an accidental start. At tbe least, fuel and mixture off, and stay out of the prop arc. Better yet, pull a plug from each cylinder.
Just slowly pull the prop thru by hand, ignition on left, buzz box on. It should show points opening near TDC (markings on flywheel are for cylinder #1). Just after you pass TDC, turn the prop backwards 30 deg (this will keep the retard coupling released), then go forward. Buzz box should sound at 25 deg BTDC as shown on flywheel.
In operation centrifugal forces release the retard coupling above some rpm, but you'll never spin it that fast by hand. Hence the 'go past TDC, backup 30 deg, go forward' method to release the coupling.

Bob -- you're talking an impulse coupling not a retard breaker. Without the starter vibrator energized via the starter solenoid the retard circuit will not function. I found this document online today that explains it: http://www.continentalmotors.aero/WorkArea/DownloadAsset.aspx?id=2147483665

There is no mechanical coupling inside a retard breaker mag.

 

[Lenny Iszak]

The retard breaker mag just has an extra set of points that open at TDC. Knowing that it's easy to test it.
To test the SlickStart you need to disconnect the starter and actuate the starter relay, because that's what powers the box. Pull a set of plugs but leave them connected and grounded to the cylinders. As you move the prop around you'll see the monstrous sparks hit at TDC. They keep on going (shower of sparks) if you stay at TDC with the prop. Looks like those sparks could start a tank!