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Its interesting, we I use 100LL I usually get 25 hours on
a set of plugs. I wonder what factors might make the difference between
your time interval and mine - "Plugs Up"?. I have not run across any
chart that indicated anything other than a plug digit which indicated a "hotter"
or a "colder version". I think I may try hotter plugs and see if
they make any difference.
Ed
----- Original Message -----
Sent: Wednesday, November 22, 2006 8:26
PM
Subject: [FlyRotary] Spark Plug Fouling
and Temperature
Ed, thanks for that article.
I installed the hotter
plugs, BUR6EQ leading and BUR8EQ trailing a month or so ago.
I guess I'll
have to start burning 100LL to see if it fixes the fouling problem.
I
usually only burn it when I'm travelling and have no other choice, but don't
have any trips planned soon.
For me, it only takes 4 hours of continuous
100LL use to get SAG and fouled leading plugs on the next takeoff.
Is there
any data anywhere that might tell us what temperature BUR6EQ, 7EQ, 8EQ, and
9EQ plugs operate at in an RX-7?
Perry
http://www.ductedfan.com
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Regarding
spark plug fouling, I knew I had come across an article that indicated
achieving certain minimum temperatures was a key factor in improving
(lessening) the fouling of spark plugs. IT sure seems that hotter plugs
may be part of the answer.
Ed
Here is the URL for that article in case anyone is
interested
..........Operating temperature of the spark plug insulator core nose
is one factor that governs formation of troublesome combustion deposits. To
help overcome this problem, selection of spark plugs with the proper heat
range should be made. Spark plugs are susceptible to carbon deposits when the
operating temperature of the core nose insulator is at or below 800o F, but an
increase of just 100o F is sufficient to eliminate formation of these
deposits. Also, lead deposits form because the bromide scavenger contained in
tetraethyl lead is nonactive at low temperatures. At 900o F temperature, the
bromide scavenger is fully activated, disposing of lead deposits with
combustion gases during exhaust cycle. In this case, an increase of just 100o
F was sufficient to make the difference between a smooth and rough running
engine. To eliminate or keep this problem at a minimum, avoid prolonged idling
at low RPM, avoid power-off let downs, and after flooded starts run engine at
medium RPM before taxiing.
Deposits formed between 1000o F and 1300o F are low in volume and
electrical conductivity and are least apt to cause spark plug fouling. This is
the reason for selecting a plug that will operate within the aforementioned
temperature range at all power settings.
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