[Mgs] MGB electric tach

[Max Heim]

As far as I can tell, you have a 3.5” diameter tach from a 1968-up MGB. So you should probably look at the wiring diagram for one of these years. I don't have any personal experience because I deal strictly with pre-68 Bs.

--
Max Heim
'66 MGB



> On Oct 23, 2024, at 3:25 PM, dave northrup <dave at ranteer.com> wrote:
> 
> Thank you for taking the time to answer
> 
> 
> -------- Original message --------
> From: Max Heim <mvheim at sonic.net>
> Date: 10/23/24 3:23 PM (GMT-06:00)
> To: mgs at autox.team.net
> Cc: dave northrup <dave at ranteer.com>
> Subject: Re: [Mgs] MGB electric tach
> 
> What year of MGB is this tach out of? It’s way too small for a Mk. I — is it out of a pillow dash car? It also lacks the inductive loop that would be present on an early car. So this tach is certainly going to be negative earth.
> 
> --
> Max Heim
> '66 MGB
> 
>> On Oct 23, 2024, at 12:25 PM, dave northrup <dave at ranteer.com> wrote:
>> 
>> Working on an MGA with a swapped in early 5 main MGB engine.
>>  
>> Trying to figure out how to set up an electric tach.  With the car came an MGA tach with the internals swapped for an MGB tach but it doesn’t work.  I purchased an MGB tach, and am trying to test it before I attempt to swap the internals for the non working one.
>>  
>> Here is a picture of the tach; there are 2 white leads, which according to the wiring diagram, one goes to the coil and one to the ignition.  Which is which?  Or should I just try them?  I know that it goes power to tach to coil.  We had the car running with the old tach but no movement of the needle before we found out that the gage was bad.
>>  
>> Also, I am assuming the extra spade in the tach goes to power?  At least the ground spade is obvious as its part of the case.
>>  
>> And, while I’m at it, the MGB wiring diagram shows one lead to the gage voltage stabilizer.  I’m thinking that can go directly to the fuse box to power?
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