Plug wires

[akflyer 1427]

Since I have had this plane I have had a bit of a mag drop on one side. It was still within the allowable limits per Rotax, but annoying none the less. I have been chasing down an EGT issue with differencial temps and the need to have the needles different on the two cylinders. In an effort to chase this down, I took off the inflight mixture from Arctic Sparrow and put the normal needles back in the carbs.

One thing I found was at some point my dumb ass had changed out an EGT probe. Obviously I was not paying any attention to it when I did it as I ended up with one long probe and one short probe, and the differences in readings was kicking my ass. I got that straight but still had a reading of about 50-80 degrees difference. I know the meters we have are not that accurate and really just show "trends" but I like the trend to be pretty much the same.

After yet another carb syncro, I still had differencial readings. I got to thinking about the mag drop I was haing so I decided to change the plug wires out, as far as I know, they were the originals wires. I ran down to the local parts store and bought some bulk 7mm plug wire. Hang onto your wallets guys, I think it cost me $6.39 I swapped out the plug wires in about 10 minutes, fired it up and now have an RPM drop of 10-20 RPM. SWEET. The added bonus, #1 my EGT readings are now showing within a few degrees of each other! #2 the very slight buzzing I had in the intercom is now gone! #3 the very slight miss I had at certain throttle settings is now gone. I am guessing it was due to having one side a step richer than needed.

Once again, When trouble shooting we should start with the most obvious, simple things instead of jumping right to the spendy stuff (coils etc.)

[EDMO 1078]

Since I have had this plane I have had a bit of a mag drop on one side. It was still within the allowable limits per Rotax, but annoying none the less. I have been chasing down an EGT issue with differencial temps and the need to have the needles different on the two cylinders. In an effort to chase this down, I took off the inflight mixture from Arctic Sparrow and put the normal needles back in the carbs.

One thing I found was at some point my dumb ass had changed out an EGT probe. Obviously I was not paying any attention to it when I did it as I ended up with one long probe and one short probe, and the differences in readings was kicking my ass. I got that straight but still had a reading of about 50-80 degrees difference. I know the meters we have are not that accurate and really just show "trends" but I like the trend to be pretty much the same.

After yet another carb syncro, I still had differencial readings. I got to thinking about the mag drop I was haing so I decided to change the plug wires out, as far as I know, they were the originals wires. I ran down to the local parts store and bought some bulk 7mm plug wire. Hang onto your wallets guys, I think it cost me $6.39 I swapped out the plug wires in about 10 minutes, fired it up and now have an RPM drop of 10-20 RPM. SWEET. The added bonus, #1 my EGT readings are now showing within a few degrees of each other! #2 the very slight buzzing I had in the intercom is now gone! #3 the very slight miss I had at certain throttle settings is now gone. I am guessing it was due to having one side a step richer than needed.

Once again, When trouble shooting we should start with the most obvious, simple things instead of jumping right to the spendy stuff (coils etc.)

Good thinking Len - Just wondering why you did not swap your originals around and check your readings first.?

Ed in MO

[akflyer 1427]

Good thinking Len - Just wondering why you did not swap your originals around and check your readings first.?

Ed in MO

Original whats? EGT probes?

[dholly 718]

This brings back some old memories. Had a '65 Ford Galaxy 500 with the big 390 police interceptor engine back in high school days, and I was having a heck of a time getting this one to run right. Then one night I lifted the hood and was shocked to find a very intense electrical show pulsing and zapping along the length of all 8 plug wires. Ran great after redoing the wires, sooo glad I saw that before grabbing a wire...

[EDMO 1078]

Original whats? EGT probes?

Sorry - meant plug wires, for the mag drop.

ED in MO

[akflyer 1427]

Sorry - meant plug wires, for the mag drop.

ED in MO

The drop was well within the rotax allowable so I did not think much about it having that great of an effect on the EGT's. I was more focused on carb issues, leaking seals, rings etc.. I had intended to replace the plug wires at the last condition inspection, but I could not find bulk wire at the time and did not want to wait to order it in. Then the plane did not get flown much due to weather and work. I thought about it again after a couple flights this spring.

[herman pahls 9]

Leni

Regarding the bulk 7mm spark plug wire from the auto parts store.

Would you give more detail about the bulk wire.

Seems like there are different core materials that prevent radio interference.

Thanks Herman

Edited 28 May 2012 by herman pahls

[akflyer 1427]

Leni

Regarding the bulk 7mm spark plug wire from the auto parts store.

Would you give more detail about the bulk wire.

Seems like there are different core materials that prevent radio interference.

Thanks Herman

Mine were just the standard copper core wires, so that is what I went back with. No interference issues with the radio with the new wires!

[birddog486 21]

Aircraft Spruce sells bulk plug wire at a decent price.