Date: Sun, 6 Dec 2009 21:55:28 -0800
Reply-To: Don Hanson <dhanson928@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson928@GMAIL.COM>
Subject: Re: Spark plugs: Gap ?
In-Reply-To: <BAY132-DS70B4E5DCBAFDE83B5BD69A0900@phx.gbl>
Content-Type: text/plain; charset=ISO-8859-1
good info..
I usually do change the plugs at about 10k miles, though this motor seems
very tolerant.
I've used the 4prong Bosch...don't like em much as I had two who's central
electrode and porcelain
inslulator got loose in the cast threaded portion....not something you
expect from an expensive 'special' plug...I only noticed because combustion
gasses discolered the insulator and ruined a very expensive set of Porsche
plug wires that were almost new...
Could have had something to do with running 100 octane race gas in a
12.5:1 compression motor and revving it way up there...
Thanks for the primer on sparkplugs..
Don Hanson
On Sun, Dec 6, 2009 at 8:18 PM, Dennis Haynes <d23haynes57@hotmail.com>wrote:
> 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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