[Mgs] Positive earth

[PaulHunt73]

If you do have the tach then the polarity of the 12v supply must be reversed inside the case as well (as mentioned in that article).

It mentions reversing the coil.  That isn't necessary and won't make any practical difference.  Original coils are wired internally to boost the HT using the 'auto-transformer' effect as well as connected externally to give a certain polarity of spark which jumps the gap easier.  If you reverse the coil you keep the polarity but lose some of the auto-transformer' effect.  If you don't you keep the full 'auto-transformer' effect but reverse the polarity of the spark.  Either could be significant on veteran low-voltage systems, which would make getting the correct polarity coil preferable.  But it should make no detectable difference to starting or running with HV systems such as ours.

PaulH.


----- Original Message ----- 
  From: Stan Fickes via Mgs 
  To: i erbs 
  Cc: mglist 
  Sent: Saturday, August 17, 2019 1:19 PM
  Subject: Re: [Mgs] Positive earth


  My '65 has an electronic tach. Look for the little loop of wire on the back. The polarity of the loop must be reversed. I cut and spliced the ends of the loop. See 
  https://www.carolinasahc.com/Tech%20Tips/Electrical/NegativeGround.html





  On Fri, Aug 16, 2019, 7:54 PM i erbs via Mgs <mgs at autox.team.net> wrote:

    Other than turning battery around and flashing the voltage regulator, are there any concerns with changing my 65 Spridget to negative ground?
    Is tach mechanical or electric?
    Thanks
    Working to restart my garage find aftet 25 years.


    Ira Erbs
    Portland, OR
    typos and artifacts are the fault of my phone
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