Oh goody a plug thread! I have always wondered about the 4 pronged affairs.
This is what's used in aircraft, and if you look in a "bomb tester" (fires the
plug under pressure with a little window so you can see the spark) you will see
that only one of the grounding electrodes is working. Makes sense: the spark
is going the easiest route. And the reason they are used is that as one
electrode wears, the next closest one will fire. At 35 bucks a pop, you don't
want to buy new ones, and you don't want one misfiring on takeoff (high
BMEP=harder to spark). So why the devil do the four prongers get sold as
performance items?????
Heat ranges: as I remember, the heat range of the plug is the speed at which
the plug transmits heat to the head. A cold plug transfers heat to the head
faster than a hot plug. A hot plug will not then bother the piston unless it is
so hot that it caused pre-ignition which in turn can cause detonation. Anyone
ever seen the damage cause by detonation? UNBELIEVABLE.
Whew. Back the rear suspension on the Mini.
Geoff Branch
'74 Meejit "Yellow Peril"
'72 Innocenti 1300 Mini
----- Original Message -----
From "Ron Soave" <soavero at yahoo.com>
To: "Spridgets" <spridgets@autox.team.net>
Sent: Saturday, August 18, 2001 1:40 PM
Subject: Re: NGK Plug Heat Ranges
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