[DML] Re: Spark plugs (was Upgrading the Air Filter)

["David Teitelbaum" <jtrealty@xxxxxxxxxxx>]

At one time Rob Grady ONLY used the platinum plugs. He started seeing
cars coming back running rough. It turned out to be the seal between
the porcelain and the metal shell was leaking and the cylinder would
loose compression. It didn't happen on every plug but at least 1 out
of the 6. He no longer advises the use of the platinum plugs. They may
have improved the seal or maybe for some weird reason it just fails in
the Delorean application. I do not see anywhere near as many cars as
he does so I would defer to his experience. Besides, the only real
advantage is the extended life, not performance. With multiple ground
electrodes each wears less so the gap changes slower so the plugs last
longer. The platinum is also more durable. I don't think even Bosch is
making any performance claims, just that they are a better plug
insofar as they wil last longer. Longevity is not the most important
thing here when most of the Deloreans see limited use. Economics has
something do do with this too. The platinum plugs are expensive. BTW
the main reason aircraft use multiple ground electodes is so if one
should break off the plug will still fire.
David Teitelbaum
vin 10757


--- In dmcnews@xxxxxxxxxxxxxxx, tobyp@xxxx wrote:
> 
> 
> Andy - Bosch originally developed the Platinum +2 for small general 
> aviation aircraft to increase reliability and avoid fouling.  
> Obviously, the plugs are far more important in an airplane than a 
> car from a safety standpoint.  What they found is that the specific 
> conditions of the ground prongs were constantly changing as 
> combustion chamber swirl, carbon build-up, and other factors entered 
> in.  The spark would jump first to one prong, and then the other.  
> It was unlikely that both would fail at once, leading to complete 
> failure of the plug.  Then, under the theory that "more is better", 
> they added another pair of prongs.  However, the spark only jumps to 
> one prong on any one firing cycle.  Is it dramatically better from a 
> strict performance standpoint?  Doubtful.  I will admit that I am 
> using +4's in all of my cars, and they are always clean and light 
> tan in color when I check them.  My Ford Explorer has 184K miles on 









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