Spark plug question: Massive electrode or fine wire?

Google shows that this question last appeared here in 2001. Therefore, I
wanted to pose it again in the event there might be more anecdotal data
since then.

Are there benefits to replacing massive electrode spark plugs with fine
wire spark plugs?

Background: I have a turbo-normalized IO-520 in the Bonanza that runs lean
of peak at cruise, an operation recommended by the turbo system's
manufacturer, Tornado Alley. This type of operation requires absolutely
clean spark plugs and a well-maintained ignition system, otherwise engine
roughness will occur.

Since the TA Turbo was installed, both the previous owner and I have had
the massive electrode spark plugs cleaned, gapped, and rotated every 100
hours. However, after reading the 2003 Aviation Consumer article I am now
wondering if I would be better served by installing fine wire spark plugs.

Given the large cost difference between the two types of plugs, I am
interested in reading others' experiences.

--
Peter

The real question in my mind is not whether fine wire plugs are better
than massive electrode, but whether fine wire plugs are reliable...
I point you to Dan Checkoway's website (rvproject.com) about building
his RV-7... Last summer he took a transcontinental trip from Los
Angeles to Prince Edward Island in the newly constructed airplane...
His engine has a magneto and a Lightspeed CD electronic ignition box...
He uses massive electrode plugs on the magneto, and fine wire
automotive plugs on the electronic box... He had significant problems
with the fine wire plugs simply failing internally, without any warning
and without any visible signs of a failure... If you wish to review
this go to his site and click on the section for the trip to PEI...
(btw, Dan's site is massive with nearly 6,000 pictures and accompanying
text, yet each page loads rapidly... Lots of web designers need to take
lessons from Dan)
Now, having raised this question, and for those who will instantly
start howling that fine wire automotive plugs and fine wire aircraft
plugs aren't the same - save your breath, I know that... I point out
Dan's experience simply as a data point, not as a claim that fine wire
aircraft plugs are prone to fail... But it does raise a question...

BTW Peter, your plugs will benefit from being serviced and rotated
every fifty hours at the time of the oil and filter change...

Denny

I used massive electrode spark plugs in my Husky for several years
(about 1500 hour flight time). They worked but needed to be cleaned. I
switched to fine wires about a year ago (300 hours), and have not had
to clean them. They are also supposed to last practically forever. We
shall see. When you do clean them use caution as the sandblaster can
damage them. Also, if you drop one, and break it, it is more. I run a
Seaplane, where NOT starting can be a major event (and need hot start
reliability). They are supposed to be better for that as well. So far
so good, no complaints.

Doug, that is a good information... Which make and heat range of
massive plug and also fine wire plug? If they have not needed
servicing for 300 hours I would be interested because my massive
electrode Champion plugs are at ~300 hours and the mechanic was whining
about wanting to put in a new set, but I made him re-gap and put them
back (they looked OK to my pocketbook)... Engines run fine..

Denny

Peter R. wrote:
Google shows that this question last appeared here in 2001. Therefore, I
wanted to pose it again in the event there might be more anecdotal data
since then.

Are there benefits to replacing massive electrode spark plugs with fine
wire spark plugs?
snip

Peter,

Based on my experience, fine wire plugs don't last as long as everyone
thinks, and certainly not long enough to justify their price.

Fine wires do last longer than massives and tend to foul less, so they
have their applications -- like some radials that wedge their plugs in
hard-to-reach areas.

However, unless you've already migrated to a "hot" massive plug and
still have fouling problems, you're better off using massives and
cleaning/rotating every 50 hours with your oil change. Then, when those
plugs go out of spec buy a new set and you'll still be ahead of the
game, pricewise.

And, yes, you read that right -- 50 hours is a good plug service
interval. I think 100 hours is far too long. The wear rates between
cylinders and between top/bottom of the same cylinder can be
dramatically different, so the plugs will last a LOT longer if the wear
is balanced across the set as they are more frequently rotated.

HTH,

-Doug

--
--------------------
Doug Vetter, CFIMEIA

http://www.dvcfi.com
--------------------

Doug Vetter wrote:

Based on my experience, fine wire plugs don't last as long as everyone
thinks, and certainly not long enough to justify their price.

Thanks, Doug, and everyone else who added their observations. Since
posting here, I called Tornado Alley to ask what they recommended.

Interestingly, they stated that I should absolutely *not* use the fine wire
plugs, for in their experience these plugs burn hotter and more uneven,
leading to the possibility of pre-ignition.

Nowhere in my research to date had this issue been remotely mentioned.

And, yes, you read that right -- 50 hours is a good plug service
interval. I think 100 hours is far too long. The wear rates between
cylinders and between top/bottom of the same cylinder can be
dramatically different, so the plugs will last a LOT longer if the wear
is balanced across the set as they are more frequently rotated.

Hmmm, just rotate every 50 hours or clean and gap, too? Both my mechanic
and the previous owner of the Bonanza, who used to race and work on high
performance race cars, recommended the 100 hour interval for cleaning and
gapping, but honestly I was unaware of the need to rotate plugs and never
asked about this.

I will bring the question of the rotating interval up with the mechanic,
who is a very well respected piston engine mechanic in these parts.


--
Peter







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Doug Vetter wrote:

Fine wires do last longer than massives and tend to foul less, so they
have their applications -- like some radials that wedge their plugs in
hard-to-reach areas.

We replaced our fine wire plugs with massives (0-300D) and our fouling
issues went away...

Peter,
I switched to fine wire about two years ago. Fouling has dis-appeared.
If you want to go half and half then put them on the bottom only. They
are more expensive but they are less headache. Works for me.
Michelle

Peter R. wrote:

Google shows that this question last appeared here in 2001. Therefore, I
wanted to pose it again in the event there might be more anecdotal data
since then.

Are there benefits to replacing massive electrode spark plugs with fine
wire spark plugs?

Background: I have a turbo-normalized IO-520 in the Bonanza that runs lean
of peak at cruise, an operation recommended by the turbo system's
manufacturer, Tornado Alley. This type of operation requires absolutely
clean spark plugs and a well-maintained ignition system, otherwise engine
roughness will occur.

Since the TA Turbo was installed, both the previous owner and I have had
the massive electrode spark plugs cleaned, gapped, and rotated every 100
hours. However, after reading the 2003 Aviation Consumer article I am now
wondering if I would be better served by installing fine wire spark plugs.

Given the large cost difference between the two types of plugs, I am
interested in reading others' experiences.

Ditto here. I replaced the bottom plugs with fine wire early last
summer. I have about 75 hrs on them, and fouling has totally
disappeared. No more burn-offs at mag check. When I had earlier put in
new massives on the bottom, they started fouling soon thereafter.

Bruce Cunningham
N30464 C177A


Peter R. wrote:
Google shows that this question last appeared here in 2001.
Therefore, I
wanted to pose it again in the event there might be more anecdotal
data
since then.

Are there benefits to replacing massive electrode spark plugs with
fine
wire spark plugs?

Background: I have a turbo-normalized IO-520 in the Bonanza that
runs lean
of peak at cruise, an operation recommended by the turbo system's
manufacturer, Tornado Alley. This type of operation requires
absolutely
clean spark plugs and a well-maintained ignition system, otherwise
engine
roughness will occur.

Since the TA Turbo was installed, both the previous owner and I have
had
the massive electrode spark plugs cleaned, gapped, and rotated every
100
hours. However, after reading the 2003 Aviation Consumer article I
am now
wondering if I would be better served by installing fine wire spark
plugs.

Given the large cost difference between the two types of plugs, I am
interested in reading others' experiences.

--
Peter

writes:

Ditto here. I replaced the bottom plugs with fine wire early last
summer. I have about 75 hrs on them, and fouling has totally
disappeared. No more burn-offs at mag check. When I had earlier put in
new massives on the bottom, they started fouling soon thereafter.

Ditto for a friend of mine with an O-200. He started with fine wires
on the bottom for one annual, and liked them so much he did the tops
the next annual. I'm trying to convince myself to do the same even
though the massives sort-a work.