Hank Posted May 5, 2017 Report Share Posted May 5, 2017 My wiring harness has some worn spots, and was pinched between the (angled) battery box and the doghouse for who knows how long. Took the battery box off to reinstall the left magneto, the wire looked pretty bad. There was also chafing on another leftside wire where it goes through the doghouse for a top plug. All top plug wires are bent sharply because of the doghouse, they are not the 90° ends. At runup, the left side has excessive RPM drop and significant the vibration (OK, it shakes). This is after rebuilding the left mag, when it ran great, flying home and it ran horrible, so I pulled the mag and sent it back in. It bench tested fine. Reinstalled and runup is still crap on the left side. The Power plant guy who reinstalled and retimed it commented on the wiring harness as we were putting it all back together and recommended getting a new one. The current one is a lightweight model (Aero Lite?). I've heard that Champion is much better. Is there something else I should look at instead? Who has the best price--Spruce, Chief, your buddy, someone else? This will probably be a Saturday project, as I'm out of town from next week through Memorial Day except for Saturdays and Sundays. Thanks, ya'll. Oh, it's for my 1970 C, in case you don't see that by my avatar. Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 5, 2017 Report Share Posted May 5, 2017 (edited) I had replaced what looked like original wires on the O360. Bought the big brand name supplied by aircraftSpruce. I probably felt better more than sensing any performance improvement. IIRC They are a high tech armored cable with a Teflon layer of insulation around a carbon(?) core. Designed to last infinitely long. (I was expecting copper wire would be good) The wires came complete from the mag top to the sparkplug boots. It was nice to get a complete fresh set of parts in place. But, knowing who the big brand name is and their history with increasing resistance spark plugs. How could they goof up such a simple yet important ignition item? Wish I had better info to report... Best regards, -a- Edited May 5, 2017 by carusoam Quote Link to comment Share on other sites More sharing options...
Mooneymite Posted May 5, 2017 Report Share Posted May 5, 2017 By "wiring harness" you are talking about the ignition leads from the mag to the plugs? I had a single ignition wire go bad on an RV-4 I owned. I kept thinking it was a bad plug, but a new ignition harness from Spruce made it all good again. Quick and easy fix. Quote Link to comment Share on other sites More sharing options...
Jim Peace Posted May 5, 2017 Report Share Posted May 5, 2017 I replaced with a new Kelly aerospace harness for slick mags. It has been perfect now for over a year and over 100 hours....no issues...... This came recommended from a highly respected mechanic who races Reno........ Quote Link to comment Share on other sites More sharing options...
Marauder Posted May 5, 2017 Report Share Posted May 5, 2017 My wiring harness has some worn spots, and was pinched between the (angled) battery box and the doghouse for who knows how long. Took the battery box off to reinstall the left magneto, the wire looked pretty bad. There was also chafing on another leftside wire where it goes through the doghouse for a top plug. All top plug wires are bent sharply because of the doghouse, they are not the 90° ends. At runup, the left side has excessive RPM drop and significant the vibration (OK, it shakes). This is after rebuilding the left mag, when it ran great, flying home and it ran horrible, so I pulled the mag and sent it back in. It bench tested fine. Reinstalled and runup is still crap on the left side. The Power plant guy who reinstalled and retimed it commented on the wiring harness as we were putting it all back together and recommended getting a new one. The current one is a lightweight model (Aero Lite?). I've heard that Champion is much better. Is there something else I should look at instead? Who has the best price--Spruce, Chief, your buddy, someone else? This will probably be a Saturday project, as I'm out of town from next week through Memorial Day except for Saturdays and Sundays. Thanks, ya'll. Oh, it's for my 1970 C, in case you don't see that by my avatar. Hank - when I replaced my plugs and harness, I went with Kelly's. Aircraft Spruce will Special order them for you. Sent from my iPhone using Tapatalk Pro 1 Quote Link to comment Share on other sites More sharing options...
Marcopolo Posted May 5, 2017 Report Share Posted May 5, 2017 +2 for Kelly Aerspace replacement harnesses. Got a great price through Aero Inc. on a set with the clockable 90* elbows. Ron Quote Link to comment Share on other sites More sharing options...
Hank Posted May 12, 2017 Author Report Share Posted May 12, 2017 Followup, been traveling and forgetting. Ordered a set of Kellys from AERO, with 90° tips. They're due in on the 18th; I'll get home late on the 19th, install and test fly on the 20th, the head out again on the big aluminum tube on the 21st. Looks like I'll get to spend some quality time under the cowl on Saturday. All I need now are some high temperature zip ties and a few grommets, so I'll measure the holes tomorrow when I'm home again and hit the PMA store on the 4-lane. Thanks, ya'll. I'll post a final report when I'm all done. Pushing two in the since the mag failed, and all I've done is fly home, spend money and work on other stuff. The joy of ownership . . . . Quote Link to comment Share on other sites More sharing options...
Hank Posted May 21, 2017 Author Report Share Posted May 21, 2017 All finished up yesterday. Tried to move the EGT lead behind the heater scat tubing g, but without disconnecting the probe, it's it going anywhere. Be ding it like that, and putting it on top of the anti-chafe bead of silicone on the hose is just foolish . . . . Engine still ran tough with 200 RPM drop on the Left mag; change gedanken would left bottom plugs it smoothed out but maintained the drop; change gedanken he trouble right bottom plugs and vibration came back. Will put the original right bottom plugs back in. Here's what came out--Fugly!! This is what happens when you run leads between the doghouse and the battery box: Quote Link to comment Share on other sites More sharing options...
Guest Posted May 21, 2017 Report Share Posted May 21, 2017 Hank, I would replace the Tyrap holding the Scat duct to the oil return line on cylinder 3. The Tyrap will damage the aluminum tube. Clarence Quote Link to comment Share on other sites More sharing options...
Hank Posted May 21, 2017 Author Report Share Posted May 21, 2017 (edited) Closeup of the pinched lead, worn completely through the shielding: And the bends on the top plugs under the doghouse: This is why I ordered the new harness with 90° tips! Plus lots of general wear, cracked / split covering, etc. One step at a time. Edited May 21, 2017 by Hank 1 Quote Link to comment Share on other sites More sharing options...
Hank Posted May 21, 2017 Author Report Share Posted May 21, 2017 1 minute ago, M20Doc said: Hank, I would replace the Tyrap holding the Scat duct to the oil return line on cylinder 3. The Tyrap will damage the aluminum tube. Clarence Thank you, Eagle Eye, sir! It's been that way for several years, and it's what kept me from moving the hose in front of the EGT lead. I suspect it is there because the tube is beginning to kink where it connects to the cabin heat box, and was added for support. Any suggestions for that, or just get new tubing? Other than that, the tube is in really good shape. Quote Link to comment Share on other sites More sharing options...
Guest Posted May 21, 2017 Report Share Posted May 21, 2017 2 hours ago, Hank said: Thank you, Eagle Eye, sir! It's been that way for several years, and it's what kept me from moving the hose in front of the EGT lead. I suspect it is there because the tube is beginning to kink where it connects to the cabin heat box, and was added for support. Any suggestions for that, or just get new tubing? Other than that, the tube is in really good shape. Hank, A few larger sized Adel clamps to secure the Scat duct to the cylinder #3 intake tube should work fine. Usually there is an eye bolt on the rudder pedal step in the firewall, an Adel clamp there as well is pretty common. Clarence Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 21, 2017 Report Share Posted May 21, 2017 Great photos Hank! Thanks for sharing the details. Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Hank Posted May 21, 2017 Author Report Share Posted May 21, 2017 3 hours ago, M20Doc said: Hank, A few larger sized Adel clamps to secure the Scat duct to the cylinder #3 intake tube should work fine. Usually there is an eye bolt on the rudder pedal step in the firewall, an Adel clamp there as well is pretty common. Clarence Thanks, I'll check next Saturday when I get home. Working on the plane while traveling the airlines is challenging . . . Quote Link to comment Share on other sites More sharing options...
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