As I remember, it doesn't matter a lot which way the current flows
between the ignition switch and the coil through the tach. It may, or
it may depend on the ground, note that the bullet connectors are
polarized, but you could rig up a test easily enough with alligator
clips and if it doesn't work just reverse them.
---
Larry Colen, lrc@red4est.com hosted at sonic
On 2024-10-23 17:39, Max Heim wrote:
> As you figured out, one white goes to â??Lâ?? on the ignition switch,
> and the other to the coil +. Based on the overall alignment, I am
> going to say the left one goes to the switch and the right one to the
> coil.
>
> The blade sticking out in the middle will be the ground to the case,
> which will be black.
>
> That leaves the other blade as green to the voltage stabilizer.
>
> FWIW...
>
> --
> Max Heim
> '66 MGB
>
>> On Oct 23, 2024, at 4:19â?¯PM, dave northrup <dave@ranteer.com>
>> wrote:
>>
>> The wiring diagram shows 4 connections to the back of the tach. I
>> have found nothing which shows which goes to which. I guess I can
>> assume that the diagram is looking at the back of the tach but
>> thatâ??s as much detail as it shows.
>>
>> From: Max Heim <mvheim@sonic.net>
>> Sent: Wednesday, October 23, 2024 6:14 PM
>> To: dave northrup <dave@ranteer.com>
>> Cc: <mgs@autox.team.net> <mgs@autox.team.net>
>> Subject: Re: [Mgs] MGB electric tach
>>
>> As far as I can tell, you have a 3.5â?? 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 3:25â?¯PM, dave northrup <dave@ranteer.com>
>> wrote:
>>
>> Thank you for taking the time to answer
>>
>> -------- Original message --------
>>
>> From: Max Heim <mvheim@sonic.net>
>>
>> Date: 10/23/24 3:23 PM (GMT-06:00)
>>
>> To: mgs@autox.team.net
>>
>> Cc: dave northrup <dave@ranteer.com>
>>
>> Subject: Re: [Mgs] MGB electric tach
>>
>> What year of MGB is this tach out of? Itâ??s way too small for a Mk.
>> I â?? 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 12:25â?¯PM, dave northrup <dave@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
>> doesnâ??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 Iâ??m at it, the MGB wiring diagram shows one lead to the
>> gage voltage stabilizer. Iâ??m thinking that can go directly to the
>> fuse box to power?
>> <20241022_175133.jpg>_______________________________________________
>>
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>
>
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