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1950/60 car electronic rev counter

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john fletcher 120/11/2018 14:14:15
449 forum posts

Help will be much appreciated. A friend has asked me to wire up a car electronic rev counter. The counter head has just three Lucar type push on terminals (1) +,(2) earth symbol, and (3) just marked 1. There is no other markings or make on the rear other than 12 V - 16000Imp. Surely not Hillman Imp ,remember them. Here I could be wrong, I seem to remember years ago some of the more expensive cars being fitted with a NON mechanical rev counter and having a wire wrapped around the HT lead from the coil to the distributor forming a sort of pulse transformer with the output to a rev counter.I'm sure members/readers will put me on the straight and narrow. John

Ian P20/11/2018 14:53:51
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1979 forum posts
86 photos

John

With a picture of the face and another showing of the connectors I am sure I will be able to identify it.

Ian P

Emgee20/11/2018 14:55:32
927 forum posts
185 photos

John

Perhaps the 16000 relates to the number of impulses per min to achieve the maximum display rpm, there will of course be a need on multi-cylinder engines for some electronics to convert the impulse from 1 cylinder to rpm for the engine.

Emgee

edit typo

Edited By Emgee on 20/11/2018 14:56:30

John Rudd20/11/2018 15:50:28
1277 forum posts
57 photos

I seem to remember from my Hillman Hunter days, the rev counters had 3 wires. Red/Black and White. The White wire connecting to the Points side of the coil...(red/black supply..)

Ian P20/11/2018 16:04:32
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1979 forum posts
86 photos

Almost certainly the wiring is as John states with (in this case) the '1' terminal going to the contact breaker. Most likely the dial will be scaled to read correctly on a 4 cylinder four stroke engine but I am only basing that on your mention of Hillman Imps and guessing that your tacho came from the same era.

Ian P

Jon Lawes20/11/2018 17:03:29
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223 forum posts

The Jag rev counter I used in my GT6 used an impulse drive of some sort which I ditched, I used a device from Spyda electronics I believe. That was to convert Smiths RVI to RVC.

Brian Sweeting20/11/2018 17:35:32
301 forum posts
1 photos

Some rev counters used a feed from the alternator, normally on diesels.

Bazyle20/11/2018 17:58:22
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4194 forum posts
171 photos
Posted by Brian Sweeting on 20/11/2018 17:35:32:

Some rev counters used a feed from the alternator, normally on diesels.

Yes, I wired the one fro my Landy to the alternator but don't quite remember where. I think it was just to the output but might have been to somewhere before the rectifier bridge. Calibration was by twiddling a screw to get the right sort of reading on tickover.

JC5420/11/2018 19:33:33
44 forum posts

A lot of land rover diesels had rev counters run from the alternator. Most of the alternators had an extra connection for tachometer display. As for the rev counter in question John has got it how we used to connect them to our "Hotrods".

Jens Eirik Skogstad20/11/2018 21:57:40
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364 forum posts
22 photos

16000 impulses,.. maybe a motorcycle tachometer? How much are the max revolution in the gauge? In case 4 cylinder 4 stroke engine can i think 16000 impulses divided by 4 (camlope in the distibutor) if the wire is connected to coil will be 4000 rpm in the tachometer.

john fletcher 122/11/2018 09:50:58
449 forum posts

Many thanks to all who responded, we think John & Ian are correct. I'll let you know the outcome later. Apparently my idea of a pulse transformer was for a genuine Smiths after market type.John

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