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  #11  
Old 06-27-2016, 08:52 AM
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AltonD AltonD is offline
 
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Quote:
Originally Posted by Ben R View Post
We did make sure the impluses had snapped before timing and they are firing right at TDC. The plugs are new aviation plugs...all auto plugs removed.
If the impulse coupling has popped, shouldn't the timing be at 25 degrees before TDC? I thought it was only TDC before the coupling had popped. In other words, the impulse coupling should snap at TDC.
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N526RV RV7A Tip Up, IO360 180 W/Hartzel BA prop.
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  #12  
Old 06-27-2016, 11:54 AM
vic syracuse vic syracuse is offline
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The impulse should snap at TDC or sometimes a little after, depending upon the lag setting of the mag.

Timing of the mag to the engine has to be done AFTER the impulse snaps. Then you turn the prop backwards to just a little before the timing mark you want, and then come up on the mark stamped on your engine for timing and set the mag so the points open (the box buzzes or lights up), typically 20-25 degrees for our engines.

If you don't let the impulse snap you will get an erroneous timing value.

Vic
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  #13  
Old 06-27-2016, 12:51 PM
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Ben R Ben R is offline
 
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Here's the technique we are using:
1. Pin the mags partially in the "L" hole and gently rotate backwards until the pin bottoms out (backwards due to the impulse coupling).
2.Confirm that the #1 cylinder is at TDC by the location of the piston (by feel) on the compression stroke which also corresponds with the TDC mark on the flywheel.
3.Rotate the prop back 20 degrees based on the timing mark on the flywheel (engine is 20 degree lag).
4.Insert the mags, snug, remove timing pins
5. Advance the prop past the impulse snap.
6. Turn prop backwards slightly past desired timing mark.
7. Advance the prop to the 20 degree mark on the flywheel and confirm that the timing lights illuminate on the synchronizer and adjust as necessary by moving the magneto slightly.

Am I missing anything?
If not, next step is to check internal mag timing per Vic's recommendation.
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  #14  
Old 06-27-2016, 01:25 PM
jrs14855 jrs14855 is offline
 
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Default Timing

The 180 hp engine should be timed to 25 degrees. Establish compression stroke on #1 cylinder. Back the prop up to slightly past 25 mark. Normal direction of rotation to 25 degree mark.
Turn the mag in the normal direction of rotation past proper timing hole until impulse snaps. Back up to timing hole. Insert pin and install mag with nuts just snug enough to allow rotation. Fine tune with buzz box.
You seem to be confusing timing mark and impulse lag angle among other things.
Once compression stroke is established on #1 you only need to be concerned with TDC if you are using a protractor style device on the spinner. NOT if you are using timing marks on ring gear support.
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  #15  
Old 06-27-2016, 01:32 PM
jrs14855 jrs14855 is offline
 
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Default Timing

To clarify this further based on your last post you likely have the mag timed somewhere around TDC. Properly timed the impulse will fire the first cylinder around 5 degrees before TDC but the impulse will then disengage and the next cylinder will fire at 25 degrees before TDC.
DON'T confuse the lag angle with the normal timing.
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  #16  
Old 06-29-2016, 02:16 PM
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Ben R Ben R is offline
 
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Default SOLVED!

Just a follow up...the problem was the E-gap setting in the mags (the mags were used). Timed them correctly internally and it's running great now. Thanks to Vic for his advice and to all who responded to the post!
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  #17  
Old 06-29-2016, 07:15 PM
PIN 37 PIN 37 is offline
 
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I know this is a little bit of thread drift but, can I ask why you (and a couple of others) have taken the Plasma II off and put mags on. I have plasma II's fitted to my 7 ?
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  #18  
Old 06-29-2016, 07:56 PM
8 ball 8 ball is offline
 
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I would remove the four top plugs, connect the wires and hand prop with ign. in on position. Spark should be nice clear blue color. The only thing changed was the mags and they are new but if you used resistor plugs and resistor wires there will be too much resistance and a very weak spark, hence very easy to flood. Regards, Carroll
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  #19  
Old 06-30-2016, 05:49 AM
Jeff Hagg Jeff Hagg is offline
 
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Default Timing

Quote:
Originally Posted by Ben R View Post
We did make sure the impluses had snapped before timing and they are firing right at TDC. The plugs are new aviation plugs...all auto plugs removed.
Set timeing to 25 degrees before TDC
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  #20  
Old 06-30-2016, 06:02 AM
vic syracuse vic syracuse is offline
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He is fixed. The internal mag timing was set wrong.

Vic
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Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
Kitplanes "Unairworthy" monthly feature
EAA Sport Aviation "Checkpoints" column
EAA Homebuilt Council Chair/member EAA BOD
Author "Pre-Buy Guide for Amateur-Built Aircraft"
www.Baselegaviation.com
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