PV: Rev counter for PV 544 with a B18

[Gigahertz2706]

Originally Posted by Rustinmotion

If it has a traditional coil it should work, I’m using a 123 ignition and the tach works fine

I looked and he also uses a 123ignition with a Bosch "High Energy Ignition Coil", like the one attached.

[Rustinmotion]

Originally Posted by Gigahertz2706

I looked and he also uses a 123ignition with a Bosch "High Energy Ignition Coil", like the one attached.

Then the one in the eBay link I sent you should work no problem

[142 Guy]

Just a thought. What is the battery voltage on your Dad's PV? Is it still a 6 volt system? The 123 ignition systems operate down to 4 volts so they can be fitted on 6 volt vehicles; but, I expect the tach will want 12 volts.

If the vehicle is 6 volts, there are work arounds to provide 12 volts to the tach. They are called boost regulators, boost converters, or charge pumps. You can probably get one from Amazon that will give you 12 volts out with 6 volts in for less than $10.

[Derek UK]

Picture shows a 12v coil so should be fine. B18 with a 12v dynamo I'd guess. Just sounds as if the wiring needs to be correct. Biltema tach is analog as it uses a needle rather than a digital display. If using a 123 dizzy there should be a wiring diagram for a tach. Google for one. Or ask 123.

https://www.123ignitionshop.com/gb/f...3ignition.html

[142 Guy]

Originally Posted by Derek UK

Picture shows a 12v coil so should be fine. B18 with a 12v dynamo I'd guess. Just sounds as if the wiring needs to be correct. Biltema tach is analog as it uses a needle rather than a digital display. If using a 123 dizzy there should be a wiring diagram for a tach. Google for one. Or ask 123.

https://www.123ignitionshop.com/gb/f...3ignition.html

A 12 volt ignition coil will work on 6 volt system with a very wimpy spark. If the owner is not technically aware, they might have just purchased 'a coil' without consideration of the operating voltage. Given that the Biltema tach wiring is 100% straight forward, something else is at play here or the owner has a very limited technical knowledge.

Small point, an analog needle does not mean a traditional analog tachometer. An awful lot of the tachs with analog needles use stepper motors to control the needle. The actual display calculation is done digitally. Stepper motors are more robust than the traditional moving coil meter movements and these days probably cheaper. All of the input, calculation and the direct control for the stepper motor can be done on one micro controller that probably sells for less than $3 if you buy a few thousand at a time.

I have a 2021 Audi A4 with traditional analog needle display for the tach and speedo and I know for a fact that the vehicle and engine speed are transmitted to the cluster via a CAN bus from the vehicle data gateway. It is digital all the way until the eyeball interface.

My 142 also has an analog display tachometer which is digital driving a stepper motor and as I referred to earlier, it requires a configuration on first power up which involves assigning the number of cylinders. It is a lump until that configuration occurs. I am a unilingual Anglophone and I can't read the Biltema instructions; but, I see the multi cylinder reference so it must have some time of configuration required for cylinder selection.

[Rustinmotion]

I think it says it can be used on a 2 to 8 cylinder engine by selecting the applicable number on the back of the gauge, are PV negative earth?

[Gigahertz2706]

Originally Posted by Rustinmotion

If it’s a dash top mount your looking for search eBay for “TIM Electronic Rev Counter Tachometer With Dash Mounting Pod”, I have exact same and it’s a good match for the interior

I can not really find anything with this, not even variations of the text.

Originally Posted by 142 Guy

Just a thought. What is the battery voltage on your Dad's PV? Is it still a 6 volt system?

Its 12 Volts.

Originally Posted by Derek UK

Just sounds as if the wiring needs to be correct. Biltema tach is analog as it uses a needle rather than a digital display. If using a 123 dizzy there should be a wiring diagram for a tach. Google for one. Or ask 123.

He said it kinda works, just that it seems as if it doesn't "update fast enough" like as if it is unable to read the sparks from the distributor correctly. He also is certain to have set it up properly, with the cylinder count and wiring.

So I am thinking, the Biltema one worked in essence, so maybe a higher quality one with the same functionality may work better. I will try and
continue to find one which is similar to the Biltema one.

Thanks for all the input guys.

[Rustinmotion]

Originally Posted by Gigahertz2706

I can not really find anything with this, not even variations of the text.

Thanks for all the input guys.

It’s uk site
https://www.ebay.co.uk/itm/226162129...mis&media=COPY

[morwenna240]

I bought a tach off eBay, I,m in Sicilia at mo so can’t nip out to car to look, the make. It’s sold for classics, looks like old style stuff found in 60’s a back motors. On back is 2, 4, 6 an 8 cyl switch, like 142 says. One wire goes to ignition switch for feed, one to earth, a one to signal, negative coil terminal. When u switch on, needle goes right round then back an settles at 800 tick over as engine running. Simples, squeak! Car is 12 v PV.