Tachometer woes!

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paulsv8manta
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Tachometer woes!

Post by paulsv8manta »

Hi guys,

my existing Tachometer is initially from a four cylinder motor.

I started the v8 engine up very briefly and the Tachometer red lined!

Do I need to buy one specifically for a v8 or do i need to check my wiring?

Cheers
Paul



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ChrisJC
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Post by ChrisJC »

A 4 cylinder tacho won't work on a V8. But redlining sounds a bit odd. It would read double if it was working properly.

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stevieturbo
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Post by stevieturbo »

A lot will depend on the actual unit.

Some may have a means of internal adjustment, or you can get creative and make it sort of adjustable.

Or use some sort of signal adjuster to change the number of pulses it sees
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gelmonkey
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Post by gelmonkey »

Paul
You need a divide by two unit which will make your tacho work
might have one here for you.
Have you managed to get a spark then and fire the old tart up?

Cheers
P

paulsv8manta
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Post by paulsv8manta »

Hi gelmonkey,
I found a break in the wire from the negative side of the coil.
When she fired up that's when I went into panic mode! Rev counter of scale, oil light that wasn't on (thought the bulb had blown) came on! Oil pressure gauge maxed out! But oh what a sweet sound!!!

DaveEFI
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Post by DaveEFI »

Depending on your electronic skills, it might be easier to replace the tach electronics with a modern IC that allows any of the common number of cylinders, and triggers easily from a low volt signal, rather than from the coil.
When I went wasted spark on my SD1, none of the adaptor circuits was 100% perfect. It's an open frame rev-counter, so easier to get at the electronics than a 'sealed' type in a housing.
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paulsv8manta
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Post by paulsv8manta »

Hi gelmonkey,
I found a break in the wire from the negative side of the coil.
When she fired up that's when I went into panic mode! Rev counter of scale, oil light that wasn't on (thought the bulb had blown) came on! Oil pressure gauge maxed out! But oh what a sweet sound!!!

gelmonkey
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Post by gelmonkey »

Re the oil gauge maxing out just swap the wires the other way around and that will sort the problem in a flash.
Bet it put a smile on your face once you heard the beast fire up mate.
You will soon have the same smile on your face as you did last weekend when I gave you a blast out in mine BUT it will be in your own car!!!!! :D

cheers
P

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