Jump to content

O-360 Wiring Harness


Recommended Posts

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. 

Link to comment
Share on other sites

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 by carusoam
Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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........

Link to comment
Share on other sites

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

  • Like 1
Link to comment
Share on other sites

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 . . . .  :huh: 

Link to comment
Share on other sites

  • 2 weeks later...

All finished up yesterday. 

20170520_123533.thumb.jpg.5b87c92b20cf1e894e36dcea1d57b9f6.jpg

20170520_123516.thumb.jpg.7290eea1019a5d5dd4c11faaef5ad442.jpg

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!!

20170520_144409.thumb.jpg.15dd2c84fa973d14c81bf79b4d1f6720.jpg

This is what happens when you run leads between the doghouse and the battery box:

20170520_144422.thumb.jpg.9bc84565a133d542cb0fb21d354ce86a.jpg

Link to comment
Share on other sites

Closeup of the pinched lead, worn completely through the shielding:

20170520_144521.thumb.jpg.af3013f68a515459faeb92642425d5f4.jpg

And the bends on the top plugs under the doghouse:

20170520_144611.thumb.jpg.263f5d085c0bdbe73fe6a521540a3f2e.jpg

This is why I ordered the new harness with 90° tips!

20170520_123540.thumb.jpg.fbfb20d6502a4f593774cc38f402ef6a.jpg

Plus lots of general wear, cracked / split covering, etc. One step at a time.

Edited by Hank
  • Like 1
Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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

Link to comment
Share on other sites

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 . . .

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.