24 replies to this topic

[mesrine]

Hello, I have recently had the good luck to obtain a 1967 mk1 cooper s 1071 cc....v nice car...first thing I have manages to do is buy and fit a NOS 60's tacho......

.followed instructions..........positive earth car, so I fitted the supplied white wire (red and black marked) between the neg side of the coil, earthed it to the body, and took a supply from the A4 side of the fuse box....fired it up and everything seemed fine, .......

.but on reflection, it seems to settle at 3000 revs, on idle, Now the car is idleing too fast and I need to alter this, but 3000 still seems a lot.......driving the rev counter seems to work pro rata, and doesnt go of the scale, its just the 3000 which is confusing me........

any observations, any tips


regards Mesrine...

[mk1coopers]

Hello, I have recently had the good luck to obtain a 1967 mk1 cooper s 1071 cc....v nice car...

The 1071 was only produced in 63' and 64', the only model available in 67' was the 1275, in answer to your question there are a couple of threads on the MK1 forum about this, plus the fitting instructions on the main site, try this one for a start

http://mk1-forum.net/viewtopic.php?f=3&t=5767

[mesrine]

Hi thanks for that, well, it is a 1967 Mk1, and a 1071 engine, and all the heratige numbers are traceable back to the supplier in Wolverhampton, the history trail confirms this......this was a cross over period for models, perhaps the original buyer, stipulated this configuration when he bought it....or it was stock sitting around, waiting for a buyer........

anyway, i think I have wired it in right,... , I removed the spade from the distributor to the neg side of the coil, and inserted the pulse loop into this break.....the tacho works ok, very smooth, not jumping around, its just that it settles at around 3000 when warm.......I admit my idle is too high, perhaps the tacho is working OK, and the revs need looking at.

by the way only had the car a week, and this is my first job, I will deal with the revs/idle next....

[mk1coopers]

Sounds like an interesting car, it's quite possible that it sat around before being sold, but 3 years would be a long time, would be good to see some pictures

Edited by mk1coopers, 30 September 2012 - 11:09 PM.

[dklawson]

I have manages to do is buy and fit a NOS 60's tacho......

.followed instructions..........positive earth car, so I fitted the supplied white wire (red and black marked) between the neg side of the coil, earthed it to the body, and took a supply from the A4 side of the fuse box....fired it up and everything seemed fine, .......

Between the negative side of the coil and what?

Since this is a positive earth application, let's not even talk about coil polarity. The impulse tachs measure current pulses flowing through the ignition coil. The easiest aftermarket installation is to open the bonnet and locate the white/black wire going between the coil and the distributor. Remove that wire at both ends. The back of your RVI tach will have a loop of wire attached. Extend those wires as necessary to reach the front of the engine. Connect one wire to the coil (where the white/black wire was. Connect the other wire to the distributor (where the white/black wire was). What you have done is to route any current flowing through the coil through the induction loop on the back of the tachometer.

If the tach works "funny", switch the two wires at the coil and distributor so current is flowing the other direction. If that does not work try to make a second loop of wire through the block on the back of the tach. Sometimes that helps. If not, it is very likely that after 40 years the transistors in the tach are failing. They can be replaced but you have to decide if the tach is worth that investment.

See this link for more information.:
http://www.speedycab...page34aaaa.html

[mesrine]

Hello Mini Doc, thanks for the input.....I have wired it in OK, tried it from the other coil terminal, and car wouldnt fire and obviously no reading....checked installation again, and OK ?

this item was NOS and boxed, and the pulse loop wire had original soldered unused ends, so I can probably safely say it has never been used before...

as of now, the counter reads a pulse, it is a steady reading, no flicking about, or wobble.....but it appear to be reading doublr, and this reading is linier, so 2000 is 4000, and 3000 is 6000 etc...........

does this help indicate a particular problem ?

Hello, I have recently had the good luck to obtain a 1967 mk1 cooper s 1071 cc....v nice car...

The 1071 was only produced in 63' and 64', the only model available in 67' was the 1275, in answer to your question there are a couple of threads on the MK1 forum about this, plus the fitting instructions on the main site, try this one for a start

http://mk1-forum.net....php?f=3&t=5767

Hi Mini mad........looked more into my paparwork, the log book says 1071 ?, it was sold to me as a 1071, but I have checked the engine and chassis numbers myself, with the heritage people again, and they confirm they go together, as a 998 sold and del to a chap in wolverhapton in 1967....must admit the spec appears uprated "S", so I am now thinking, when the car was rebuilt it was up rated then, there are a lot of parts lists with it, I will scrutinise them with time........so I am sad that I was missled a bit, but on the otherhand it appears a great car, and is a matched body and engine going back to 67, all be it uprated......buyer beware as they say.....

[tiger99]

It occurs to me that the tacho is possibly seeing double pulses, which makes it read double. (Could even be triple?) Do you have anything non-standard in your ignition system, such as an electronic module? Are the points and "condenser" in good condition? (You will probably be justified in thinking that they are if the engine is running well, but there are some obscure circumstances which might give rise to double pulses, such as a very weak, or even too strong, contact spring, allowing the points to bounce.

Or, as Doug suggests, some internal components in the tacho have failed, and it is sensing the pulses at too low a level so minor ringing on the signal is being seen as proper pulses. I don't have details of the internals of these tachos, but I don't imagine that they are at all difficult for a specialist to fix. Bound to be simple discrete transistor stuff. Not a microprocessor in sight!

[dklawson]

Please post a picture of how you have made your wiring connections at the coil and distributor.

EDIT: Tiger, from what I remember, there are only two old-style Gallium-Arsenide transistors. They are easy enough to replace when you find the modern substitute (I believe NTE makes them). The only other part that I think routinely fails is a foil type cap. I think it is a 25 uF but most fit a 22 uF since it's necessary to recalibrate anyway.

Edited by dklawson, 08 October 2012 - 07:04 PM.

[mk3 Cooper S]

Is it a 4 cylinder tacho ?

[mesrine]

Is it a 4 cylinder tacho ?

yes it is for 4 cylinders....

[mesrine]

It occurs to me that the tacho is possibly seeing double pulses, which makes it read double. (Could even be triple?) Do you have anything non-standard in your ignition system, such as an electronic module? Are the points and "condenser" in good condition? (You will probably be justified in thinking that they are if the engine is running well, but there are some obscure circumstances which might give rise to double pulses, such as a very weak, or even too strong, contact spring, allowing the points to bounce.

Or, as Doug suggests, some internal components in the tacho have failed, and it is sensing the pulses at too low a level so minor ringing on the signal is being seen as proper pulses. I don't have details of the internals of these tachos, but I don't imagine that they are at all difficult for a specialist to fix. Bound to be simple discrete transistor stuff. Not a microprocessor in sight!


I did have to extend the supplied pulse wire, and the loop ends are installed together at the coil terminal, they are side by side, so, if my extended wire has less insulation, and with them being in close proximity to each other, then a "double pulse pick up, may be the problem.....I will move them apart, to see if this is the simple answer.........thanks for advice gentlemen................

[dklawson]

I did have to extend the supplied pulse wire, and the loop ends are installed together at the coil terminal, they are side by side, so, if my extended wire has less insulation, and with them being in close proximity to each other, then a "double pulse pick up, may be the problem.....I will move them apart, to see if this is the simple answer.........thanks for advice gentlemen................

I really want to see a picture. The wiring as described is wrong.

The coil current flows THROUGH that loop on the back of the tachometer. You have to have a current pulse (not voltage) so coil current has to flow through that loop. Proximity to other wires is not going to give you double pulses unless the loop wires are connected "wrong" and acting as an antenna. Regardless, the ends of the loop wires should NOT be next to each other.

Wire as follows.... Locate the white/black wire going between the coil and distributor. Disconnect both ends of the white/black wire. Connect one tach loop wire to the coil terminal where you removed the white/black wire. Connect the other tach loop wire to the distributor where the white/black wire was removed. That is it for the sense wiring. Note that the two loop wire terminals are not next to each other.

Please post a picture of how you have connected the wires.

[mesrine]

hi took some pics will get them posted...

[mesrine]

hello

do these pictures help,

regarding the rev counter reverse. the plain yellow wire is to the fuse box power source, both yell/green are earths, red is the light...

car is positive earth, and the counter is for 4 cyl.

.the coil picture, shows the spade to the distributor removed, and thats where i have inserted my pulse lead.....it shows the the pulse lead is inserted on the neg side of the coil

regds ray

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[mk3 Cooper S]

What is the other covered terminal on the back odf he tacho fo then?