Date: Sun, 6 Dec 2009 23:18:32 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Spark plugs: Gap ?
In-Reply-To: <6bc66ccf0912052148p2b001058kb9d76a00b68acd3@mail.gmail.com>
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How long do you think those spark plugs should last? Center electrode
erosion is a normal occurrence for these engines and ignition systems. Most
of the erosion occurs from the heated electrode losing some material as the
electrons flow from the center electrode to the outer electrode with each
spark. The normal plug replacement interval for these engines was 15,000
miles. The proper gap is only part of proper spark plug set up. The center
electrode should be sharp and square, the center electrode should not only
be gapped but parallel to the face of the center electrode. This all help
the spark to jump "easier" under adverse conditions. The VW ignition system
is really tolerant of excessive gaps until the coil says enough and fails
internally from the high voltages. Lean and high speed miss fires can go
unnoticed. When the center electrodes are worn enough that the plugs need to
be re-gapped it is time for new plugs.
The Platinum tipped plugs have almost no center electrode erosion and the
quad tips fire real easily. They are an upgrade and they easily last to 30K.
As there is less "electrode mass" in the combustion chamber to glow they
also help to avoid pre-ignition.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Don Hanson
Sent: Sunday, December 06, 2009 12:49 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Spark plugs: Gap ?
Doing my fall maintence this day and I pulled the spark plugs to check how
things were burning in my inline 4 jetta powered van. Easy as pie, btw, on
that motor.
As is usually the case they look to be in perfect tune with the mixture
but again "as usual" the gap has grown a lot over about 20k miles of mainly
highway driving. I put them in gapped at 30 and they were eroded or
whatever out to nearly 40. What causes that? and how critical is the gap?
The motor was running fine despite the way over spec gap in every plug.
Re-gapped and re-inserted, I could detect no difference in how the motor
sounds or runs...Would I have more power show on a dyno with the proper
gap? Better starting? Cooler running? Less chance of pre-ignition?
Just curious..
Don Hanson
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