|
|
The key to pilot's reaction to SAG is the slight (?) throttle reduction - my
experience with auto spark plugs as compression ratio of newer engines (back
in 1956 era) went up, was that plugs were "sensitive" to pressure - more
compression, and higher throttle settings, and a marginal plug would
miss-fire. Reduce throttle - especially at idle - and everything seemed
smooth and fine.
I used to wonder why "cleaning" (sand blasting) the plugs didn't help much.
Another lister recently mentioned that the sand puts pits in the center
ceramic (and maybe metal outer cyl of plug also?), which then accumulates
carbon at an increasing rate and starts shorting out the plug sooner and
sooner.
Bead blasting has replaced "Sand" blasting for many applications - has it
been applied to spark plug cleaners? If not, then I'd experiment with that
method of cleaning and see it the plugs could be reinstalled and last a
reasonable time.
David
----- Original Message ----- From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, January 25, 2005 12:08 PM
Subject: [FlyRotary] Re: FW: Re: Plugs and Mags
No, I'm not certain, Mark,
However, the plugs are not necessary worn out at 20-30 or 100 hours on
MoGas
but they must have the center ceramic cleaned of lead or carbon deposits.
Not arguing that platinum and Iridium plugs won't give longer life - just
don't believe they will go significant longer before the SAG hits.
Those that have not yet hit the SAG have a thrill awaiting. The first
time
your engine drops in rpm and the EGT drops 300F, you'll likely think some
major problem has occurred. For months I though I had erratic fuel
injectors or some intermittent fuel problem. Tracy is the one that put me
onto the plugs - change to new plugs and the problem ends immediately.
Generally backing off on the power seems to help temporarily and the
condition will go away on its on (after getting your heart beat
accelerated)
to recur at ever increasingly frequent intervals. Seems to happened
mostly
at high power settings - like on takeoff where you really don't want
anything unusual from the engine. Even though I have had it happen a
number
of times, I still have not gotten use to it {:>)
Ed A
----- Original Message -----
From: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, January 25, 2005 12:35 PM
Subject: [FlyRotary] Re: FW: Re: Plugs and Mags
Ed,
Do you know what type of plugs Tracy uses, el-cheapo or platinum? You
said that he runs mo-gas so I assume he doesn't have the lead-fouling
problem you and others have. So, I assume Tracy's plugs are actually
worn out after 100 hours? If that's the case, it seems that the
platinum, or iridium plugs might give longer life.
Mark S.
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of WRJJRS@aol.com
Sent: Tuesday, January 25, 2005 11:28 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: FW: Re: Plugs and Mags
Not certain that reciprocating engines have the same problems as their
plugs
are not as shrouded as ours so combustion process probably help keeps
blowing off deposits on the ceramic center cone.
FWIW
Ed A
>> Homepage: http://www.flyrotary.com/
>> Archive: http://lancaironline.net/lists/flyrotary/List.html
>> Homepage: http://www.flyrotary.com/
>> Archive: http://lancaironline.net/lists/flyrotary/List.html
|
|