mgs
[Top] [All Lists]

Re: sprak plugs "fouling out".

To: Bill Schooler <schooler@erols.com>
Subject: Re: sprak plugs "fouling out".
From: stevet@hbp.com (Steve Tritle)
Date: Sun, 27 Jul 1997 19:12:49 -0400
Bill Schooler wrote:
> 
> James W. Dunn wrote:
> >
> > Hello,
> >
> >      I have a problem wtih my 52 MGTD with the spark plugs
> >  "fouling out".  I can't seem to get more than 80 miles on a new
> >  set of plugs.  When i remove the plugs they are coated with a fluffy
> >  black coating, so I put in a new set and the car runs great for
> >  another 80 miles or so and then they have to be changed again,
> >     The engine was overhauled about a year and a half ago with
> >  many new parts.  The car has just been tuned including points,
> >  condenser, rotor and dist cap, also the valves were adjusted, the
> >  timeing set and the carbs adjusted.  I checked the compression
> > and all the cylinders were within normal limits for this engine.  The
> > engine doesn't seem to use much oil and I haven't noticed any black
> > smoke coming for the exhasut pipe.  I use champion L82C spark
> > plugs set at .025 and even tried .035 with same results.
> >     Any help greatly appreciated as I'm tired of changing sparks plugs.
> >
> >  Thanks,
> >  Jim Dunn
> >  52 MGTD
> >  Birmingham, Alabama
> 
> Jim,
> 
> Although you said the carbs were tuned, I would expect you are dealing
> with an overly rich mixture, or incomplete combustion.  Regarding the
> rich mixture question:  in the rebuild/tuneup process, were the carb
> jets and needles replaced?  I am going to defer to the TD operators
> about the heat range of your spark plug.
> 
> As far as incomplete combustion goes, are you using the correct "reach"
> plug for your head?  3/4 inch or 1/2?  And is it correct for your
> particular head?  There were two different designs of cylinder heads
> used in the TD, and the casting change caused a change in spark plug
> reach.  I'm going to cite Chip Old on this matter:  "The simplest way
> (to tell which one you've got), although I'm not sure it is foolproof,
> is to look for the number which is cast into the top surface of the
> cylinder head at the front right corner.  All XPAG heads I have seen or
> heard about which bear the number 22592 are early heads, which
> ...require 1/2 in reach plugs.  The later heads bear several different
> numbers, but as far as I have been able to determine any head showing
> any number other than 22592 requires 3/4 in reach  plugs."  The
> "foolproof" way to tell requires the head be removed.  Again citing
> Olds, "Check the water holes on the head which conduct coolant from the
> engine block to the head.  If they are oblong (banana-shaped), then you
> have an early head.  If round, the head is a late one."
> 
> Here's why I went through this dialogue.  Chip Olds explains, "If a 1/2
> in plug is used in a head designed for 3/4 in plugs, the engine will run
> but the electrodes of the plug will be shrouded by the unfilled part of
> the spark plug hole and will foul rapidly".  Hoo boy - does this match
> your symptoms, or what!  Chip goes on to explain the often dire
> consequences of using the longer reach plug in the older head.  You
> don't want to do that.
> 
> Sorry about the length, and I hope this is of some help.
> 
> --
> *Bill Schooler      *Check the MGCC Wash DC Centre Web Page
> *Woodbridge, VA     *http://members.aol.com/mgccwdcc/
> *schooler@erols.com *Editor of The Spark
> *69 B/GT, 53 TD     *Web Page Coordinator
I don't think you need to go to that extent. Simply remove a plug, bend
a stiff wire and inset in the plug hole and measure the distance.

Steve
52 TD

<Prev in Thread] Current Thread [Next in Thread>