Dual ignition timing

[Gripdana]

I had a rough running engine. I tested the primary ignition according to the service bulletin and found I needed to replace the ignition modules. So I just replaced them and now the primary ignition switch shuts off the ignition. I went to check the ignitions to see how close the rpm's are. What I have is as follows. 1600 rpm for both on. 1525 primary on and secondary off. 1530 primary off and secondary on. I retarded the secondary and the secondary was further off and advanced it to what I have now. I am wondering if I may have a bad plug/s? My EGT's and CHT have always been under the maximum allowable. Everything was well tuned prior to the last flight that the engine started running rough. Any suggestions? I did send a note to sonex.

[wlarson861]

Check plugs and ignition wires. Before that check the drop at 1900 rpm and see if it is less pronounced. AT 1900 I see about 35 to 50 rpm drop with primary only and 50 to 70 on electronic only.

[radfordc]

I used to do my mag checks at 2000 rpm at least. Also, lean the mixture to get a smooth running engine before doing the mag checks.

[mike20sm]

Not sure if this is relevant, but I recently learned a lot reading Mike Busch's articles on this kind of thing:

http://a.moirier.free.fr/Pilotage/Au%20sol/The%20mag%20check.pdf

https://www.savvymx.com/index.php/articles The EGT myths debunked was good too.

[Jim1342]

Mike is there a secret to getting into Busch's articles? When I clicked on (http://sonexbuilders.us8.list-manage.co ... cb603f39e7) it sent me to a page with a series of articles but when I clicked on one of the articles It sent me to never-never land.

[mike20sm]

Mike is there a secret to getting into Busch's articles? When I clicked on (http://sonexbuilders.us8.list-manage.co ... cb603f39e7) it sent me to a page with a series of articles but when I clicked on one of the articles It sent me to never-never land.

Yeah that list is just a list and not a link to the actual article. The best way is to go here and look at the Sport Aviation Archive http://www.eaa.org/en/eaa/aviation-education-and-resources

[Gripdana]

I have not posted the results of my ignition. I sent the magnate one back to Sonex and mine were defective. They would spark but could not be shut off. I replaced the magnetrons and test ran the engine. At the lower rpm there was a wide rpm difference. I re tested at 2000 rpm and had little change. Then test flew the plane for a couple of hours and did the airborne test per the Aerovee manual and the CHT's were with in a few degrees. I also found a ground from the engine block to the FW ground block loose. That was fixed before the test flight. So now the engine is running great.

[mike20sm]

Glad to hear it's running smooth again. Did you loctite the grounding cable so it won't happen again?

[Gripdana]

It was a bad crimp. I fixed it and ordered a new factory made cable from B & C. That was my plan from the start but I never got around to ordering it.