O 470k spark plug suggestions

leadsledfan

leadsledfan

New member
I have noticed a widening gap in the mag drops between left and right.
My thought is that a couple plugs are probably tired, and the wire leads definitely appear beyond their time.
My plan is to replace both sets of plug wires and install new plugs to try to even out the mag drop.
This is apparently part of my never ending quest to become the aircraft spruce customer of the month.

What are my fellow master owners using? Favorite plugs? Favorite wires?

Ps. I am so happy that I am not chasing 14mm plugs from WWII for the master..
 
Check the timing. If the timing is off the mag drop spread will open up, but the motor will be smooth on either mag. If there is a miss on either mag the spark plug/wire is suspect.
If one of the mags timing is off significantly look for a worn cam follower on the points.
 
It runs much rougher on the left mag. But it is somewhat intermittent. I only truly noticed on the last trip. Most of my run ups will give me mag drop around 50 rpm, on in one leg of the last trip, I had a mag drop of around 100 on the left mag.
 
Adam, was that 100 rpm drop a one time occurrence or is it consistent drop? Still within allowable limits. As Ralph said, you ought to check mag timing. That would be a LOT cheaper than new harness and plugs. When was the last 500 hr mag inspection? Did they check internal mag timing (e-gap)?
Did you try to do a hard lean on run up...could have been a fouled plug from start up to run up if you're burning 100ll and didn't lean during taxi. Did it also happen in flight?
Do you have 6 cyl egt installed yet? That would be a quick way allow to locate the plug and lead if the mag timing is not an issue.
BTW, I heard you on Travis approach last friday...I was flying the 182 that they chopped as I was heading to Livermore.
 
Larry,
What were you doing cheating on your Bellanca with a Spam can cessna!?

I was returning from Idaho that day and had spent all afternoon dodging the storm over washington and oregon.

The mag drop is consistent enough to warrant replacement of the wire leads. They are at least 600 hours old (the overhaul shop put their tags on them), and look fairly poor in condition. I have an edm 700 and have twice noticed that cylinder 4 has been slow to warm. My guess is that the failure is on that cylinder. I have also noticed a very infrequent miss at cruise.

I am fairly set on replacing at least the left mag's wire leads (one mag is getting electronic ignition soon which will have new leads), and would like to go ahead and buy a set of plug's and do a cleaning / replacement of any that fail testing.

What is the recommended plug from the master' owners? Iridium? Massive?
 
Reading the Forum from Denali Park AK. I like the Champion REM 40 plugs and they have served me well in the crate for 15 yrs. The cheapest route to trouble shoot your mag drop is to install new plugs if yours are old. Now you have eliminated the 1st source of excessive drop. The other course of course is to swap plugs from rt mag to left and if the mag drop switches you now know you have bad plugs. Trying to justify spending 350 bucks for Cessna 180 flight to see the tall one. WX permitting. Lynn the crate :wink:
 
Thanks Lynn! It is so nice having spark plugs readily available for the bellanca.. no more rej38's cutting into my flying budget
 
Well another item in the bucket list. I was in the right seat of a Piper Navahoe at 12K ft around Denali. I can only say that the Mt. :!: and ride were overwhelming. It was a clear day and you just can't grasp the enormity of it all. What a thrill and a great ride! Oh, it was well worth the money. Just to TO and Land on that gravel strip DENALI AIR. Lynn the crate
 
A rough mag check could be caused by high resistance in one spark plug. You should always check your plugs with a simple ohmmeter when they are out during the Annual Inspection. The plug resistance should be between 1500 - 5000 ohms. A high resistance plug will fail to fire and put stress on the magneto coil, leading to early failure.
Champion plugs are notorious for this failure mode. I have experienced a few. You can use a flat blade screwdriver to remove the resistor cover screw, spring & resistor. I cleaned up the inside of the plug and the correct resistance was restored, but I didn't return the plug to service.
Tempest plugs are more reliable and cost less. The resistor is fused in place. I buy these now.
The Ignition Harness is easily tested with a High Voltage Cable Tester Model E5, your A&P should loan you his, or you can buy one from a supplier like Aircraft Spruce.
http://www.aircraftspruce.com/catalog/topages/cabletester.php?clickkey=11343
I keep mine with the Magneto Timing Light Model E50 and the cylinder leak down tester.
I replaced the harness on my (now sold) Cessna 182 during a 500 hour mag inspection, the new harness was defective, would not fire one spark plug. The E5 tester confirmed it and Continental sent out a new harness (with some persuasion from Magneto Services)
 
Good to see Tempest and Champion warring with one another. Makes for a better product and with the price so sky high that product should be faultless. Lynn the crate
 
You must log in or register to reply here.
Back
Top