Date:         Sat, 15 Feb 2003 11:40:54 -0500
Reply-To:     Allan S Muller <photoallan@PHOTOALLAN.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Allan S Muller <photoallan@PHOTOALLAN.COM>
Subject:      Re: Gap of Sparks
In-Reply-To:  <BA739EEF.2810%mwmiller@cwnet.com>
Content-Type: text/plain; charset="US-ASCII"

It all works together. The gap of the plug is important because it can
affect when the plug fires. Wider the gap the later it fires, closer the
gap the sooner it fires for a given voltage. If the gap is correct, and
the timing is correct, the wires, cap, rotor, points or pickup are in
good condition then the plugs will fire and ignite the fuel/air mixture
at the proper position of the piston. All the variables need be inline
for proper performance.

The other factors are the condition of the spark plug wires (resistance
of the wire; cracks in the insulation causing shorts to place they don't
belong, etc.) the condition of the coil (resistance and ability to
produce the correct Voltage to the distributor and on to the wires,
spark plug wires are affected by age/heat/voltage load carried etc.
They don't last forever.

Allan

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Mike Miller
Sent: Saturday, February 15, 2003 10:38 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Gap of Sparks

Ben,

You're probably right but doesn't when the points close [either directly
or
as a sensor] determine when the plug fires, not the distance across the
gap?

Somebody on this list has got to know how this works really.  Given the
state of my knowledge practically anybody will do.

Where's David B when we need him?

Sylvan!  Wake the old bear up.



Mike


On 2/14/03 11:20 PM, "Ben McCafferty" <ben@VOLKSCAFE.COM> wrote:

> No, I think you're right and we're saying the same thing.  Now I'm
really
> reaching here back to high school physics, but if I recall correctly,
it
> takes about 20,000 volts to jump 1 centimeter.  Can someone confirm or
> refute that?  In any case, if it takes more volts to jump a longer
distance,
> a larger gap would mean higher voltage before the spark would get
across,
> and a smaller gap would mean lower voltage to get across.  I think
that
> means smaller gap=quicker spark=lower voltage=cooler fire and larger
> gap=slower spark=higher voltage=hotter fire.
>
> Am I missing something here?
> tx,
> bmc  :)
> Ben McCafferty
> ben@volkscafe.com
>
> Volks Cafe
> 1823 Soquel Avenue
> Santa Cruz, CA  95062
> 831-426-1244
> http://volkscafe.com
>
>
>> From: Mike Miller <mwmiller@CWNET.COM>
>> Reply-To: Mike Miller <mwmiller@CWNET.COM>
>> Date: Fri, 14 Feb 2003 23:07:21 -0800
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Re: Gap of Sparks
>>
>> Really?
>>
>> Darn I misunderstood gap and timing then.  I thought too wide a gap
and it
>> was hard for the plug to fire and too narrow and the spark wasn't big
enough
>> to light the fire efficiently.
>>
>> Mike
>>
>> On 2/14/03 5:37 PM, "Ben McCafferty" <ben@VOLKSCAFE.COM> wrote:
>>
>>> If gap is too short, spark happens early; if too long, spark happens
late.
>>> In either case it will affect timing and combustion.  I believe it
will also
>>> tend to shorten the life of the electrode on the plug, but I'll let
the EEs
>>> chime in on that.
>>> tx,
>>> bmc  :)
>>> Ben McCafferty
>>> ben@volkscafe.com
>>>
>>> Volks Cafe
>>> 1823 Soquel Avenue
>>> Santa Cruz, CA  95062
>>> 831-426-1244
>>> http://volkscafe.com
>>>
>>>
>>>> From: Mark Dorm <mark_hb@HOTMAIL.COM>
>>>> Reply-To: Mark Dorm <mark_hb@HOTMAIL.COM>
>>>> Date: Fri, 14 Feb 2003 12:16:49 -0800
>>>> To: vanagon@GERRY.VANAGON.COM
>>>> Subject: Re: Gap of Sparks
>>>>
>>>> So what happens when the sparks you've got installed are not of the
correct
>>>> gap? I use only W7CCO by Bosch
>>>>
>>>>
>>>>
>>>>
>>>>> From: Mike Miller <mwmiller@cwnet.com>
>>>>
>>>>>
>>>>> I only use Bosch and they're rarely the correct gap right out of
the box.
>>>>>
>>>>> Mike
>>>>>
>>>>> On 2/14/03 9:24 AM, "Mark Dorm" <mark_hb@HOTMAIL.COM> wrote:
>>>>>
>>>>>> I thought Bosch plugs were preset to gap no problem...
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> As to the slow starting, there's lots of things, but have you
checked
>>>>> your
>>>>>>> timing?  Also, with your new plugs, did you check the gap?  Lots
of
>>>>> times
>>>>>>> people think they come preset to the correct gap, and they
usually
>>>>> don't.
>>>>>>>
>>>>>>> tx,
>>>>>>> bmc  :)
>>>>>>> Ben McCafferty
>>>>>>> ben@volkscafe.com
>>>>>>>
>>>>>>
>>>>>>
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>

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