Date: Sat, 15 Feb 2003 23:36:49 -0600
Reply-To: Stan Wilder <wilden1@JUNO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stan Wilder <wilden1@JUNO.COM>
Subject: Re: Gap of Sparks - Note correction
Content-Type: text/plain; charset=us-ascii
My air cooled will not even start with the electronic ignition
COIL. I've been told that the electronic COIL produces more
current / spark.
-------------------------
On Sat, 15 Feb 2003 22:50:58 -0600 Stan Wilder <wilden1@JUNO.COM> writes:
> I've been laying out of this because you guys have got the ignition
> system pretty well down pat.
> I've had some good and bad experiences with VW distributors, mostly
> 009
> and the 205 that is on air cooled vanagons.
> Good tight distributors with good cams are important to achieve
> full
> power from an engine with a point set ignition.
> Vertical shaft movement can cause point dwell to change because the
> cams
> are traveling both in rotation and a vertical jump at various times
> of
> acceleration or just idling.
> Testing the cam is easy enough just by rotating the cam to each high
> cam
> position and measuring the point opening with feeler gauges. You can
> also
> use a dial gauge if you can get it rigged properly (not easy).
> One revolution isn't enough testing, it needs to be tested for three
> or
> more revolutions to verify properly.
> I've found cam shafts with strange wear patterns that are .002 out
> from
> one cam high to the other cam high positions. This in effect
> changes
> dwell and will cause premature or late plug firing. The condition
> can be
> caused by slightly bent distributor drives or on drives that have
> had
> pitting due to rust. Running the shaft dry can cause excessive wear
> down
> of a single cam lobe while the others appear correct.
> The spring under the Vanagon and most VW distributor drives is
> supposed
> to stop vertical bounce caused by the gear bouncing on the lower
> crank
> contact gear. However under hard deceleration the drive will draw
> down on
> the spring, this doesn't cause any problems but as the drive
> travels
> upward it gives the distributor a little advance of 1+ degrees and
> can
> cause an occasional backfire.
> Vertical bounce happens under deceleration and acceleration of the
> engine
> at high RPMs.
> If the brass drive gear on the crankshaft is worn unevenly or is
> just a
> sloppy fit it can cause advance / retard changes that you cam measure
> by
> accelerating the engine several times and noting the variances.
> I've proven to myself that good distributors are a necessity for
> proper
> delivery of spark to the plugs.
> Having a box of about ten distributors in various condition has
> given me
> the tools to experiment and disparity can be detected even with
> simple
> tach, dwell meters of good quality.
> Carefully accelerating the engine while watching the advance on the
> timing arc and multiple cycles at various RPMs can detect
> distributor
> advance slowdown or vacillation.
> One war story I might relate here is that I've found long screws
> holding
> point sets down, they lock out the advance if they are longer than
> 3/8"
> long.
> If you've had a distributor showing rust, pitting or other signs of
> moisture exposure that is abnormal you can find weak counterweight
> springs that will cause too fast advance.
> Someone just mentioned that the point set and electronic ignition
> coils
> are the same ........... I doubt this.
> My air cooled will not even start with the electronic ignition
> distributor. I've been told that the electronic distributor produces
> more
> current / spark.
> It has been suggested that Air Cooled vanagons could run hotter
> plugs
> without damage if you want to peruse it.
> Hotter plugs can cause detonation in some operating environments so
> take
> caution on going too hot.
>
> Stan Wilder
> 83 Air Cooled Westfalia
>
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