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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
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