Bob Turner
Well-known member
- Joined
- Apr 4, 2018
- Messages
- 3,912
Just sticking this here to add some activity - you can see my long progression on the J3 Cub forum.
Sent my spare S4LN-21s out for a 500 hour check - mags have always been right at the edge of my competence, even though I had to talk my way through one during my oral 49 years ago. Mag overhauler said they were obsolete, needing new rotors, coils, and impulse couplings. $1850 each, please.
So I had them send them back - discovered first that they had disassembled them, and failed to re-assemble them in operable condition. So I had to learn how to do that - and in the process I found just how simple these neat little spark things really are. I also discovered that they had been upgraded with new rotors, coils, and a stamped "C" on the case, indicating compliance with the latest AD. So from now on I shall be doing my own 500 hour checks. One of my students has the bench test setup, so after I am done I can verify my work, with a short one hour round trip to Ramona.
The saga began in earnest when I ordered a pair of QAA rebuilds from Spruce - almost $1700 each with a core deposit, so about $500 cheaper than overhauling my old set with the new parts. I built a new harness with Packard 440 and those neat but obsolete Pamcor swaged ends (I have the tool, but am running out of sleeves). The new mag/harness failed right off the bat - 200 rpm drop. So it could only be the new mag or the harness.
That is where I learned how to disassemble and properly re-assemble the S4 mag. I tried one of the returned mags, to isolate the problem. Then I discovered that it had been reassembled in an inoperative fashion.
On and on - but the final determination: One of my new Packard 440 leads failed the cable tester. A visual inspection and an Ohm meter check doesn't show it, but the cable tester (high tension) sure does! Fixing that today, and happy that I have two spare magnetos - the entire fleet is now converted to Bendix. Maybe I should sell the Eisemanns (fully functional, but need e-gap setting) to an unsuspecting Cub type. Nah - I will give them to the first starry-eyed kid with a Cub or Champ.
Bottom line - I really learned a lot by not first checking the new sparkplug harness!
Sent my spare S4LN-21s out for a 500 hour check - mags have always been right at the edge of my competence, even though I had to talk my way through one during my oral 49 years ago. Mag overhauler said they were obsolete, needing new rotors, coils, and impulse couplings. $1850 each, please.
So I had them send them back - discovered first that they had disassembled them, and failed to re-assemble them in operable condition. So I had to learn how to do that - and in the process I found just how simple these neat little spark things really are. I also discovered that they had been upgraded with new rotors, coils, and a stamped "C" on the case, indicating compliance with the latest AD. So from now on I shall be doing my own 500 hour checks. One of my students has the bench test setup, so after I am done I can verify my work, with a short one hour round trip to Ramona.
The saga began in earnest when I ordered a pair of QAA rebuilds from Spruce - almost $1700 each with a core deposit, so about $500 cheaper than overhauling my old set with the new parts. I built a new harness with Packard 440 and those neat but obsolete Pamcor swaged ends (I have the tool, but am running out of sleeves). The new mag/harness failed right off the bat - 200 rpm drop. So it could only be the new mag or the harness.
That is where I learned how to disassemble and properly re-assemble the S4 mag. I tried one of the returned mags, to isolate the problem. Then I discovered that it had been reassembled in an inoperative fashion.
On and on - but the final determination: One of my new Packard 440 leads failed the cable tester. A visual inspection and an Ohm meter check doesn't show it, but the cable tester (high tension) sure does! Fixing that today, and happy that I have two spare magnetos - the entire fleet is now converted to Bendix. Maybe I should sell the Eisemanns (fully functional, but need e-gap setting) to an unsuspecting Cub type. Nah - I will give them to the first starry-eyed kid with a Cub or Champ.
Bottom line - I really learned a lot by not first checking the new sparkplug harness!
