The other day I went to change my oil and plugs, but one of the
   plugs had seized and getting it out really did a number on the
   threads in the housing and cam out with several of the deepest
   threads caked with aluminum.

   I went and got a tap and helicoil kit...

   I re-tapped the threads and the new spark plug seems now to fit
   fine and snug up OK, but I am a little worried about all the
   damage that must have been done. I am now trying to decide
   which is the lesser of two evils. Leaving the threads as is if
   the spark plug can get torqued to spec, VS. installing the heli
   coil and possibly getting aluminum shavings into the combustion
   chamber. I would stuff it with grease soaked rags, but there is
   always a concern. Up sizing the hole for the heli coil will
   make a LOT of shavings.

   My though is that if the threads can tolerate the proper torque,
   then they should be good to go.

   Opinions?

   Does anyone know the proper torque on the spark plugs?
   --
   David Leonard

   Turbo Rotary RV-6 N4VY
   http://N4VY.RotaryRoster.net
   http://RotaryRoster.net

   http://www.ngksparkplugs.com/techinfo/spark_plugs/installation.asp

   The engine should survive a few aluminum shavings. They should
melt   the first time it fires. No guaranty :)

   Use a grease soaked string.

   I would pump (with a grease gun) the top dead chamber full of
   Vaseline before you started drilling and tapping. Then rotate it
   around to the exhaust port and dig the Vaseline with the chips out
   from there.
   Then flush it with auto TX oil.

   Paul Lamar

   I'm sending spark plug torquing instructions recently posted by Lynn
   Hanover. Hope it is of some help.

   Mark

   Now tighten the new plug into a scrap housing, or your wife's
Honda   to 14 foot pounds and then back out. This to flatten the sealing
  washer.
   Then wipe on just a hint of Nickel anti-seize on the threads. Nothing
   within 1/4" of the tip. Practice torqueing to 10 pounds with
   extension sticking through between your middle and ring fingers.
   Torque a plug into a scrap housing to 9 pounds, then turn it by hand
   to what you think is 10 pounds. Then check the plug with the
wrench   set at 11 pounds. The plug should turn a bit to get to 11 pounds.
   Get a feel for 10 pounds using your wrist only. 10 pounds with
lube   is plenty. After a few installations the anti-seize will have
been   spread all the way to the inside end of the plug hole. Great heat
   conductivity. Plugs will never lock up in the hole. Threads will
   last as long as the housing.

   Always use a torque wrench. But if none is available you can do
the  ring   finger trick and get 10 pounds every time. Only you
tighten plugs,   not your ham fisted brother in law.

   Lyn Hannover

   For a plug torque chart, go to;
   www.championsparkpluds.com/charglossary.asp
  <http://www.championsparkpluds.com/charglossary.asp

   Plugs can also be tightened properly without a torque wrench. For
   new plugs or
   with a new gasket I think it is 1/8 turn from finger tight. If
   reusing the
   gasket, 1/16 turn from finger tight. You need to be sure the plug
is   contacting the gasket surface of the housing at finger tight. Never
   seize on
   the threads. If it wants to turn more than prescribed without
   snugging up, it
   was not on the gasket surface. Taper seat is 1/16 turn from finger
   tight.

   Dale Davies

  First, DO NOT USE A HELICOIL! Sorry to shout but helicoiling spark
plugs  has always been a bad thing to do. The helicoil partially
insulates the  plug and that can require you to use a colder plug.
 The best insert you can use for the plug hole repair is called a "Time
  Sert". Made by the Time fastener Company they are the best inserts
you  can buy, period. Search Time Sert on the web to find their
site. The  plug inserts are steel but they are copper plated to
insure proper heat  transfer. Look them up you will be glad you did.
I won't use anything  else now.  Bill Jepson

  Still have your RV10 Kit Bill?

  Paul Lamar

Hi Bill,
It's funny that you feel so strongly about Time Sert.  I did know of
them from my search, but most people seemed to weakly recommend the
heli-coil.  As far as heat transfer, it does not make much sense to
me that a alum-copper-steel-copper-alum interface should necessarily
do any better than alum-steel-alum...  no matter though, because it
is easy to start using cooler plugs if needed.

I liked the idea of a coil as a means of taking up any slop and
preventing any breakage.  Lastly, Todd Archer told me about some
certified aircraft engine that comes new with helicoils.

That being said, it is not too late for me to switch.  I taped out
the hole today and feel confident that I got out all themetal chips big
enough to do any harm.  But when inserting the coil it mis-threaded and
had to be removed, which destroyed it. So now I still have my choice.

At the auto parts store there was an insert that appeared to be black
anodized alloy, or the heli-coil (both labeled as generic inserts)  does
that sound like the Time Sert?  Do you think the threads are going
to be the same for the two?

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net


There is another style thread insert, but I do not recommend it of spark
plugs. The name is Keensert and the OD is bigger than Helicoil. They use
regular taps, a slightly larger drill than would be standard for that tap and
have lock pins you tap down wwhen it is installed to lock it in so it can not
come out. Great for bolts in Aluminum heads and intake manifolds.

If the outside thread on the timesert has a different thread, I would try
running the tap for the Helicoil in again to clean it up. The coils are a bit
tricky to start into the thread. A bit of gentle wiggling usually does the
trick. Also use the proper installer tool.

Dale Davies