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From: Dale Rogers <rogersda@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Spark Plug cleaners 
Date: Sat, 27 Nov 2004 10:06:47 -0500
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My experience parallels David's.  In the mid-50's when I 
started working in my daddy's service station (back when 
you could actually get FULL services from a gas station) 
one of my first jobs was to clean plugs with a sandblast 
plug cleaner like Harbor Freight sells.  This was back when 
a set of plugs for a V-8 cost half a day's pay, so if 
cleaning would make 'em last another 4-5 thousand miles, 
most customers would opt for cleaning over replacement.

As time went on, I learned that cleaning wasn't very 
effective on the plugs for the four-barrel V-8's, and 
we recommended against trying the cleaning option.  (It's 
bad customer relations when you do a tune-up and it 
doesn't run any better - or only does so for a week or two.)

Eventually, I understood that it was the high-compression 
that seemed to make the difference.  Cleaning the plugs 
not only removes the deposits but it texturizes the 
surface of the porcelain.  That opens the way for deposits 
to collect more quickly and provide a path for the current
to bypass the gap.

I would recommend against having "cleaned" plugs as my 
on-board spares.  And use the sandblaster sparingly.

Oh, yeah, and "wet" plugs.  Spray 'em with brake cleaner; 
it gets oil and gas out of the cavity and leaves a dry, 
residue-free plug.

Dale R.
COZY MkIV #1254
Ch's 4, 5 & 23 in progress.
 
> From: "David Carter" <dcarter@datarecall.net>
> Date: 2004/11/26 Fri PM 11:44:16 EST
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Spark Plug cleaners (was Re: [FlyRotary] Re:
>  Bernie Kerr had fire in the hole!
> 
> Ken,
> 
> I didn't see any responses to your observation about plug cleaners.
> 
> I used to use plug cleaners all the time in 1954 Ford 6 (low 7.x to 1
> compression ratio) and on my VW.  They didn't seem to do as much good on
> higher compression 1956 Chev'y power pack engine (8.5? to 1 "high"
> compression) - plugs had to be good - cleaning and re-using didn't seem to
> work well.
> 
> Have I heard that a "cleaned used plug" is not as effective as a "new plug"
> in the rotary engine after flooding?  If there is such anecdotal info, then
> I wonder if the "hard to start unless new plugs" is due more to loss of
> compression due to loss of oil film and resulting need for "max good spark"?
> I wonder if squirting some extra oil in the plug holes for each rotor face
> wouldn't help it start better, maybe with "cleaned plugs"?  Leon Prommet
> mentioned a long time ago that an ideal engine setup would have a little
> tank of some concoction of oil (he mentioned brake fluid??) that would be
> allowed to drip into the intake just before shutdown to "fog" the engine
> really good (coat parts with a robust oil film) before shutdown.
> 
> Just wonder if "cleaned plugs" have been given a "bum rap".
> 
> David