[Mgs] MGA with 5 main MGB engine

[PaulHunt73]

Obvious correction - I assume the MGA would be positive earth originally 
like early MGBs, so it should read "Have you converted the car the 
negative earth" if the tach you have is a negative earth.

On 30/07/2023 10:07, Paul Hunt wrote:
>
> Which tach?  Where did it come from?
>
> For an MGB tach 'yes' if it has RVI on the dial.  No if it has RVC, 
> for that you need a wire back from the points side of the coil to the 
> tach bullet connection.
>
> Plus 12v and earth connections to the tach to power the electronics, 
> and that raises further questions. Have you converted the car to 
> positive earth? If not unless the tach is already negative earth (the 
> _original_ polarity is also on the face of MGB tachs for example) you 
> will need to reverse the power wires inside the tach case and also the 
> signal wires, which can be inside the tach or outside depending on 
> which tach you have.
>
> PaulH.
>
>
> On 30/07/2023 01:50, dave northrup wrote:
>>
>> I am trying to figure out how to connect the tach on this car.  it 
>> came to me in kit form
>>
>> This diagram seems to show that in essence the connection from power 
>> to the ignition coil goes through the tach.  That green wire goes off 
>> to the gage voltage stabilizer – is that even needed?
>>
>> So it seems to me that on my car, which has an original early  MGA 
>> wiring harness, all I really need to do is run the white wire through 
>> the tach then to the ignition coil, instead of going straight to the 
>> ignition coil.  Am I on the right tach here (haha)?
>>
>>
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