Wiring a tachometer

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btorvestad
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Wiring a tachometer

Post by btorvestad » Thu Nov 29, 2018 7:10 pm

Hello! I got a 3-dial instrument cluster for my Marina Mk1 1.3 and would like some guidance on how to wire the tachometer. What does it connect to?



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enthusiastic youth
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Re: Wiring a tachometer

Post by enthusiastic youth » Mon Dec 03, 2018 7:11 pm

There are two bullet style connecters at the back of it at least, plus one coming from the circuitboard(?). If these connecters are already in your car, then happy days! If not, it should need power, ground and coil signal but I’m not sure were they shold go on the tach. I could check it for you but someone on here should know ;)
Plus I seem to recall a complete wiring diagram on here somewhere :think:
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david painter
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Re: Wiring a tachometer

Post by david painter » Mon Dec 03, 2018 7:13 pm

Can you post a picture of rear of you rev counter
Dave

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Re: Wiring a tachometer

Post by david painter » Mon Dec 03, 2018 7:41 pm

See attached 1275 GT wiring Diagram as this uses same rev counter item 95 on picture Green wire usually Spade connector is Fused IGN switch + Bullet Connector White Black to - side of coil (points side) you will also need to earth the rev counter when I converted my mk3 Coupe the wiring was not in the harness ( nice mk3 Coupe thread ) I added the required wiring and used it to make a simple imoboliser as well I don't know if the wire is pre installed on a mk1 though
Dave
1275gt wiring dia-page-001.jpg
1275gt wiring dia-page-002.jpg

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btorvestad
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Re: Wiring a tachometer

Post by btorvestad » Mon Dec 03, 2018 10:03 pm

Thanks guys! This is helping me in the right direction and I’ll see if I can make sense of this:) Here is a picture of the back of the tacho with two connectors to the right of the red wire.

Tried to search for the mentioned thread but did not find it. Do you remember which category it was in?

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david painter
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Re: Wiring a tachometer

Post by david painter » Tue Dec 04, 2018 7:40 am

Based on the picture I have found of a mini, The male bullet has an original White /Black wire to it, this would be connected to coil Negative, may be marked CB but is points side of coil. It is difficult to see what your terminals are like from the angle of the photo. My Coupe thread is in readers projects.
Dave
mini revcounter.jpg

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btorvestad
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Re: Wiring a tachometer

Post by btorvestad » Tue Dec 04, 2018 10:58 pm

Image

Here is a better picture of the terminals. That thread on your nice Mk3 was very good by the way. Awesome project!


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okeh
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Re: Wiring a tachometer

Post by okeh » Wed Dec 05, 2018 12:28 am

My Austin Marina came with the two gauge cluster, and this past summer I put in a three gauge cluster. All of the wiring for the rev counter was already in the harness, so hook up was easy. Since the car came with a pertronix, I purchased an RVC 2430 rev counter from Ebay instead of using the existing RVI gauge that came with the cluster. Theoretically it should be fine with the electronic ignition, unlike the RVI, and it was for about 3 weeks, read dead steady - and then the needle pegged to the far right, and that was it. So I guess its fried and its now disconnected. Possibly I shouldn't have used the existing wiring! Once the car is out of storage I'll try the earlier rev counter.

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Re: Wiring a tachometer

Post by david painter » Wed Dec 05, 2018 7:41 am

From the picture I think you have a RVI not a RVC unit this will be written in small letters on the front face usually at the bottom. The RVI is current sensing and is wired in series to the Ignition coil SW + side this type will not work with electronic ignition. Glad you like the tread
Dave

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Re: Wiring a tachometer

Post by locost_bryan » Wed Dec 05, 2018 9:42 am

When I replaced the clock in my Mk1 Super with the tachometer, I didn't have to change any of the wiring. Memory's a bit vague as to whether I had to change the flexible printed circuit.
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btorvestad
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Re: Wiring a tachometer

Post by btorvestad » Wed Dec 05, 2018 10:14 pm

You’re right David. It is an RVI. Does it go on the coil and negative earth then?

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Re: Wiring a tachometer

Post by david painter » Thu Dec 06, 2018 7:57 am

No it doesn't a RVI is a inductive type and is wired, in series between ignition switch and live + side of the coil. Depending if BL used same wiring harness on 1.3 and 1.8 you might find a white wire loose behind instrument cluster with two bullet connectors in it. If yes happy days just unplug connectors and connect to back of Tacho if not you are going to have to find the white wire from ignition switch to coil + SW. Cut it and connect to Tacho the live side of wire, will connect to male bullet yellow in picture and the coil side to female bullet blue in picture, the spade orange in picture is a live that you have your red wire connected to. Do not use diagram I posted earlier as that is for a RVC Tacho! See new diagram as this what you need with a RVI. I have assumed your car is Negative earth. On the front of the dial in the small writing at the bottom where it says RVI will also be written either Negative or Positive earth, it will only be compatible with the earth type written on the face. A RVI does not normally work if you have a electronic ignition fitted.
Dave
RVI tacho.jpg
RVI tacho.jpg
Attachments
RVI wiring dia.png

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btorvestad
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Re: Wiring a tachometer

Post by btorvestad » Thu Dec 06, 2018 7:21 pm

Fantastic! Pretty certain I understand it now and I really appreciate that you take your time to explain in such detail. Will let you know once I get to it. Both the car and tacho are wired negative earth.


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david painter
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Re: Wiring a tachometer

Post by david painter » Thu Dec 06, 2018 8:11 pm

No probs I enjoy sorting a problem and happy to help. Hope it all goes well for you anything else you need to know feel free to ask.
Dave

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btorvestad
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Re: Wiring a tachometer

Post by btorvestad » Thu Dec 06, 2018 10:47 pm

It does not seem like it shares harness with the 1.8. I have located the white wire from the ignition and will wire the tacho in series as described. Any recommendation on wire thickness to get?
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