Bill,

My take on the spark plug heat range is that one would want the coldest plug available as long as it doesn't foul resulting in misfire.  I saw no evidence of fouling in either location so I don't think the BR10EIX are too cold.

Steve

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From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Bill Bradburry <flyrotary@lancaironline.net>
Sent: Friday, January 8, 2016 12:24 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Tuning

 

Steve,

 

The factory plugs for the Renesis leading application are 21 mm and the trailing are 19 mm.  The BR10EIX are 19 mm, wouldn’t this make them even colder in the leading location?  Should the leading be hotter than the trailing???  Does it matter??

 

Bill

 

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From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Thursday, January 07, 2016 12:06 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Tuning

 

When using stock spark plugs, I would get 15 to 20 hours of use before encountering SAG.  With BR10 EIX spark plugs in both leading and trailing locations, I did not have any problems for 180 hours.  I don't know how long they would have gone since they were changed simply due to the gap widening as the electrodes became worn.  They were still working fine when removed.  No leaded fuel was used. 

 

Steve Boese

RV6A, 1986 13B NA, RD1A, EC2

 

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From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Lehanover <flyrotary@lancaironline.net>
Sent: Tuesday, January 5, 2016 10:22 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Tuning

 

Try this:

 

Gap the plugs down to .010". I used a MSD-6A on both leading and trailing. No misses up to 9,600 RPM.

 

For 100% duty cycle 11.5 is the heat range you want. 9s and 10s are too hot. There is an Autolite plug

 

about the 10 heat range but I am in Florida and all of my data in Hebron Ohio. The NGK 11.5 plugs are $25.00 each and are retracted tip side electrode. Can be gapped and are ice cold. A 12.7 mixture should get you 1575 to 1600 EGTs. Once on top, lean to stumble of slight sag then back rich a bit for economy, or lean to best RPM for best power. Best timing is 25 to 27 degrees BTDC for higher octanes. Lower octane fuel works better than higher octane fuel. In that case 22 to 24 degrees. The rotary needs little advance as there is a long dwell near TDC. The timing marks on the crank are moving 3 times faster than the rotor. IE 30 degrees on the pulley is 10 degrees at the rotor.

 

The timing marks can be added to the front pulley or to the flywheel teeth. Often the flywheel is better. Divide the flywheel tooth count by 360 to get the degrees per tooth. Find TDC. Mark a flexplate (or flywheel) tooth next to your new rigid pointer with red paint (for TDC). Then turn the engine backwards the correct number of teeth to find the advance number you want to run. Mark that tooth or valley between teeth with white paint  right next to your pointer. No curve, advance weights or vacuum anything is required as the engine will start and idle at full advance. Now you can set your timing dead on and it is easy to see and check from time to time. No tuning is possible without the correct timing to begin with.

 

Both leading and trailing may be fired at once. The split timing is mostly for pollution control. It has very little affect at speed.

 

Lynn E. Hanover

 

   

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