Jensen heritage for the next generation

Instruments & Interior

Dear Diary discusses the instruments & interior to Jensen FF chassis number 119/191

From the Jensen FF Mk1 sales literature relating to instruments & interior: “Safety belts to both seats which are fitted with finely adjustable reclining hinges incorporating quick release for access to rear seats. Map pockets to both doors. Center mounted lockable compartment. Covered pockets in rear armrests. 16 cu. ft. (45 m3) luggage compartment with spring loaded self supporting lid. Radio: Fully transistorised, twin speakers”

Photographs of cockpit

Revcounter pod removed showing burnt out white/black wire (due to mice nest inside dash) going from ignition switch via rev counter to Ballast resistor mounted by coil. (Note the speedometer head was replaced under warranty at 86 miles due to a “seized head” ( part No. CT.888 ) )

View behind front pod

The beginnings of the mice nest

The nest. Note also the wing nuts on the second photograph, that holds the center pod in place.

Slightly more detailed view of burnt out wire going through rev counter sensor. It should be a white wire that is actually wrapped twice round a terminal, that is, an inductive type pickup. The type of wire I personally used to replace the burnt out one was rated at 18 amps, (it runs between the ignition switch and ballast resistor) isn’t relevant. However the direction that the wire runs through the tachometer is. At first I just ran the replacement wire through the tachometer terminal and it wouldn’t work. Then on advice, I reversed the direction of run through the tachometer, looped it and it worked (You have to feed it back on itself and it feels all wrong ) There is no electrical connection with the white wire, just this white wire, ground and power. I understand that the tachometer usually over reads on recommissioning. Easy to adjust though, with the screw at the back. Evidently this type of tachometer is rare and isn’t on any other car other than CV8s, Mk1 Int and FF.

Some months later the tachometer stopped working and I once again asked the list about it. Their (and my) responses were:

Problem solved. As you all may remember my rev counter stopped working and I wanted to trace the voltage stabiliser to see if it was that. Thanks to the list I found and replaced the stabiliser (£12 + VAT from Cropredy Bridge Garage) which made no difference at all and then having done a few more tests ended up buying a second hand rev counter from Cropredy Bridge Garage (about 30- 40 minutes away) for £20. (Out of interest they sell reconditioned ones for £50). I also contacted Speedograph Richfield Ltd (mentioned below) and they advised that it would be £50 too, depending on what was wrong and it would be 2-3 weeks at the moment and even longer when the light nights start (all prices relate to 2005).

A summary of the responses and an additional question posed by someone else follows:

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Photo1 shows the location of the voltage stabiliser. Photo 2 shows the old (right hand side) and replacement (left hand side) stabilisers. Note one of the pairs of terminals on the new one are female not male as on the original one. I’m not sure if it is correct, particularly as the fuel gauge seems to be more inaccurate than ever.

1. The stabiliser is under the dash mounted on the steering column. The flasher is there too. If I remember right? You just look under the steering wheel to see it. Mine was easy to see.
2. The voltage stabiliser either works or it doesn’t. So either the gauges show nothing or full (in the case of the fuel gauge)
3. My guess would be that something apparently unrelated (like setting the points, moving a ballast resistor, removing the thing to clean it, replacing wires) has caused it to appear to fail. Or it could just be a bad earth. I doubt that the Tach is compatible with a Mopar electronic ignition conversion. Ideally, I would try it on another car to make sure it is OK. I have had one fail, and bought a car once with a genuinely broken one. Some components in these things degenerate with age, and I replaced some components and got the thing going again. The location of the special wire on the back of the tach is critical. I would think that a bad earth is more likely than a voltage stabiliser problem. Hopefully there isn’t really a problem. I suspect that if you send it to an instrument repairer in the UK it will more than likely come back ruined.
4. I also have a ’69 Mk1 Interceptor, and had a similar problem. I found the following when fault finding the Tacho
1. The voltage stabiliser only operates the fuel gauge, not the tacho.
With the ignition on:-
2. Is your fuel gauge working?
3. Is your ammeter showing charge when the engine is running?
4. Are the heater fans operational?
5. With the ignition on, have you got 12v on the green wire connected to the back of the tacho?
If the answers to the above are yes, then it could be either the sensor connections (coil or ignition switch), or indeed a faulty tacho. I found the problem to be a high resistance fuse holder. A PO had bypassed nearly all of the circuits going through the original 2 fuse fuseblock, EXCEPT one. This one caused the problem. A quick bypass with a blade type fuse holder and fuse cured the problem. Have you got the wiring diagram from the JOC website? Its not 100% for the late Mk1’s, but it really helps. Hope this helps
5. Apparently someone has removed the voltage stabiliser, as all? Instruments are not reading accurately. The Voltage stabilizer (sometimes there are two) gives a 10V supply for the instruments. Smiths/Jaeger gauges require a feed of 10V. Check thoroughly the earthing of the instruments as well.
6. Speedograph Richfield Ltd, Arnold, Nottingham, they use to do all my sunbeam tiger gauges, they have been in the business since 1912, a proper company but please get a quote and time period off them to carry out repairs, they normally are very busy.
7. The only instrument running off the stabilizer is the tank gauge. (Oil and temp are mechanical devices, the rev.counter is internally stabilized. Ammeter runs off the current passing through it.) If it is inaccurate I’d check all the connections first. I cannot recall where it is, but if you fail to locate it mail me, I may have a photo of it. Regarding the rev.counter, I assume you haven’t changed anything, like bypassing the ballast resistor circuit? And the connection still use the little plastic “shoe” where the wire pass through the “hoop” at the back of the instrument? And the supply does actually supply? If all is well in the above departments, did it die gradually, or suddenly? If gradually, I’d suspect one of the capacitors as the main culprit. If suddenly, either a soldered connection or the internal voltage stabilizer. I had mine apart some time ago, and I think it uses a Zener diode for this. They don’t live forever, and in particular they will burn out if you have a serious over voltage. Not knowing the specs, I would guess that a trip with a dead regulator resulting in say 16V may kill it.
8. Can I ask a question? My rev counter runs very high, and even higher in hot weather. I remember an article in one of the JOC magazines about the possibility of adjusting it. Do you know if this can be done while installed (in a C-V8 MKIII)? I don’t know where to stick the screwdriver…so to speak. Removing the instrument looks like a job, disrupting wiring, etc. Maybe I’m just too chicken to get in there and wrench it out. Thanks! Answer: Those old things didn’t have temperature compensation, but even so it shouldn’t be very noticeable. I’d start by adjusting the basic level first. It does have an adjustment screw inside, at least on my cars (’67 and ’68). According to John W. some later ones have a hole at the back, sometimes retaining it’s little plastic plug to prevent ingress of dirt. The hole should be about 10mm to the left of the hole for the bulb illuminating the rev. counter, seen from the rear of the unit. The adjusting potentiometer has a white plastic disc with an indent for the screwdriver. You should be able to see it anyhow through the hole for the bulb. I have taken the counters apart and drilled holes in mine. But be very careful not to touch any moving parts, and remove all traces of metallic residue after drilling. Plug the hole after adjusting, or at least stick a piece of ducting tape over it. Hopefully the wires on your car are long enough that you can pull the counter out and tilt it slightly with all wires connected so that you can adjust it in situ. I have a dwell meter with revcounter as well which I connected in the engine bay and leaned on the windscreen. Then with the engine running I adjusted the tacho. Temperature sensitivity, if it remains high after adjustment I’d say it’s overhaul time if the engine is nice and smooth. The tacho will misread if you have bouncing breakers or a failing coil for instance, but the engine will show signs of misbehaving in that case. Check out with a secondary revcounter before doing anything drastic.

9. Until the 1980s most tank gauges incorporating a warning light worked like this: A float on an arm connected to a rotational potentiometer (sealed unit) is
submerged in the tank, only the top visible. Three wires are connected to the unit in the tank: Ground, warning light and potmeter. The primary resistor track inside the unit is for the gauge and is “ON” continually but giving varying resistance according to position, resulting in an inversely varying current. The warning light comes on when a second set of contacts meet in the unit, giving full current when this happens and continues to do so while the fuel level sinks further. The connection for the warning lamp thus gives 12V to the lamp when activated. The Voltage stabilizer feeds the gauge which is grounded via the tank unit. In all cases known to me nil resistance (and thus full current) is when the tank is full and the float in the tank in the top position. From this you can see that as long as the tank unit has not been physically disturbed or damaged, the warning light will come on at the right time, irrespective of the gauge. But the gauge will show too much if the supply goes above the stipulated 9 or 10V (I don’t know what is correct for yours), making the gauge think the level is higher that it actually is. A regulator will either give null or full when faulty, so I’d check the voltage at the supply side of the gauge. (But bad connections can of course lower the output by the time it reaches the instrument to be supplied.

Final update to the List:

Firstly, I recently replaced the voltage stabiliser on my 1969 Mk 1 FF with one I bought from Cropredy Bridge garage. However, it had one pair of female terminals and one pair of male terminals on the back , whereas the original one on the vehicle had two pairs of male terminals . I adapted the female terminal on the new voltage stabiliser to a male one so as to fit the female connector on the wire. After reinstalling the unit it made no difference to the rev counter, which was the original reason for doing it and which I now understand is only to be expected, but the new one produced a faulty low reading on the fuel gauge.Having comprehensively tested the new and old stabilisers with the engine off and with it running my voltmeter indicated that they were producing different voltages. The new one produced a varying voltage between 2 volts and 6 volts and resulted in a low reading on the fuel gauge. The old unit produced varying voltages between 5 and 11 volts. I reinstalled the original voltage stabiliser and all is now well. There is obviously a difference between the stabilisers, which I will be taking up with Cropredy. I suppose the different connectors should have warned me but I just thought over the years it had been superseded by a generic one. Secondly, having fixed my rev counter? I found, as another writer did that it read too high. Per suggested drilling a hole in the back of the rev counter to expose the adjuster inside I drilled the hole and adjusted the rev counter, comparing it against my trusty Gunson’s Testune. Perfect.

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Photos of the adjustment of the rev counter which was showing about 1500 rpm more than it should have. Arrow shows the location of the hole drilled to allow access to the adjuster. Adjusted using a small elect. screwdriver. Very easy and satisfying job

Photos showing speedometer cable attachment at autobox end.

Photo showing the eight tracks’ amplifier? hidden under passenger dash. This unit connects to the eight track/radio through a 9 pin socket.

On December 25th 2003 I received a mp3 player for installation in the Jensen. This meant I could put the Voxson 8 track back and still be able to play my music. A friend investigated the old set-up and how I could put in the equipment:

The stereo speakers have a common earth unlike more modern set-ups.
There are two red (left channel) and two black (right channel) wires for the stereo speakers. Each pair has one large and one small female spade connector. The large connector is the earth connector, which is obviously negative in the Jensen’s case. The smaller one is positive. They will be connected as appropriate to the speakers. Make sure both speakers use the same connection method because although the speakers will work they will be working out of phase.
As you want to keep the Voxson radio/8 track and install your MP3 player (which has separate volume and other controls and pre amp only) in a discreet place, you have a few choices. You will need to either use the existing amplifier or replace it with a new one.
If using the existing amplifier you have 3 options:
1. QUALITY OK: use an FM modulator, which will simply connect the MP3 player to the aerial socket on your radio. The radio is then simply tuned to the correct frequency, which will the pick up the MP3 players music. Most straight forward. Or
2. BEST QUALITY: Connect directly into the amplifier, which is what we have done because it was already out of your car. We connected it internally as per the pictures/diagrams the lead used was standard RCA stereo phono lead terminating in two standard female phono sockets. One end was cut and soldered to the terminals inside the Jensen amplifier (using the common earth where the metal braided sheath from the thick green and thick white wires is already soldered. And then soldering one of the two remaining wires to the joint where the thin white signal wire for the left channel is soldered and finally soldering the remaining wire to the right channel signal wire joint. -See diagrams/ photos. This I think was much easier and less damaging than cutting into the existing thick umbilical wire (nine pin) and splicing into the speaker wires which are the thick green (right channel) and thick white (left channel) wires (note these thick wires each contain a thin white wire surrounded by a metal braided sheath (common earth). To operate this system and avoid the radio signal being played all you need do, after switching on at the radio and mp3 player is turn down the radio volume and use the MP3 player volume control.
3. QUALITY VARIABLE: Bad idea? – Connect up the mp3 player, then buy an 8 track cartridge to cassette adapter and cassette/cd adapter. Put the last adapter into the first adapter and then the first adapter into the 8-track player. You end up with a wire coming out of the cartridge slot in the 8-track. However, you would just make all the problems with 8 track systems even worse (lots of misalignment problems)

If you were replacing the existing amplifier because it isn’t very good or broken or you just don’t have one:
1. Buy a new amplifier which could be powered via the radio by picking up on what would have been the power lead return from the radio to amplifier (white/red wire connected to socket/pin No 7 as per diag.) and which becomes live when the radio is switched on. You could tape up the exposed nine pin connector. Cut into the umbilical wire and splice into the thick green and white signal wires as mentioned above and connect these to the new amplifier. You will also need to provide a fused live feed to the thick black/white wire (live feed for the radio that would have come from the amplifier). I think you can safely ignore the other wires as they are to do with polarity and amplifier operation. The more drastic alternative would be to just cut through the umbilical wire and make the three connections.
2. If you wanted to attach your mp3 player to this set up then splice into the signal wires leading to the new amplifier or use an adapter (4 leads into two) to allow the second signal from the mp3 player to connect into the amplifier signal input phono sockets The amplifier and mp3 would have their own live inputs and on/off switches. With the amplifier switched on you could chose to switch on and use either the radio/8track or mp3 player. If both were switched on you would have to turn down the volume on the one not being used so that there was no signal from that unit to interfere with the other. Note because of the way the original Jensen amplifier works it is not separately switched.

N.B.(1). The live feed for the radio comes via the amplifier through the umbilical wire (thick black/white wire socket/pin No. 8 on diag.) N.B. (2) a cd changer needs a different approach because there is not normally a separate control module as you have on the mp3 player.

Photo of the Voxson radio/8-track

Photo of underside of radio showing trimmer screw

Photo showing the separate amplifier pair of red wires feed the left speakers, pair of black the right. Grey wire has an inline fuse attached and is the live feed. Thick umbilical wire has the 9 pin socket

Side view of amplifier showing the positive/negative earth switch

View showing amp and radio connected (connector clamp loose on wire)

Views of the 9 pin connector

Photo with the important? wires detailed

View showing the signal wire connections inside amp. Note the common earth

General view of signal wire connections


Photo showing the new additional soldered connections for the signal input from the mp3 player

The original idea of running the Mp3 player through the original amplifier failed. After connecting everything up the player only ran through one channel and with allot of interference noise. Another specialist said it would never work because the output from the Mp3 player would never be enough to for the old analogue amplifier? As it was at some point during the process I broke the amplifier. So I revisited an idea that Douge Myer told me he used on his wife’s Mk1 interceptor. Put a modern setup behind the Dash pod and use the face plate off the 8-track to give the appearance of originality.

I used a spare Sony tape player that had less depth than the CD player I had and would drop back below the face of the pod. I couldn’t bear the though of cutting a bigger hole in the original pod so I bought a second hand one, cut the whole and transferred over the instruments. I then connected up an FM modulator (came with the mp3 player) and fitted the mp3 player under the front seat. I chose this location as opposed to the boot because I thought the environment in the cockpit area would be more hospitable.

I needed to raise the seat a little so the mp3 player mounted beneath the seat would move over the crossmember in the floor when the seat was moved backwards or forwards. Access to remove the hard drive is from the front under the drivers seat.

The necessary wiring runs up the side of the transmission tunnel, under the centre cubby, behind the centre instrument panel to the hidden radio cassette.

Final result. Still needs some crinkle finish black paint. There is a small hinge underneath and the face plate luckily just clips home when pushed up. The face plate and bits are easily remove from the 8-track without damage and could be returned if I find the time to ever go down the originality route.

Photos showing location of the switch for the factory fitted rear speakers.

Photos showing manufacturers cut outs in parcel shelf for additional speakers..

Rear seat removed showing the 4 mounting rubbers. The two bottom ones are about half an inch thick and the two top ones are about one inch thick.

Photo of the emergency boot release between spare tyre and rear valance

Photos showing electric window winder on offside door. The gunge all over the inside of the door is Dinitrol waxoil.

Photo of headlining

Photos inside boot area.

Photo showing steering wheel boss and fitting

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Photos 1 & 2 showing rear view mirror with integral interior light.



I’ve recently fitted rear seat belts. They were Securon aftermarket
belts but I opened them up and removed the bit of the workings that stops the retracting mechanism working when the unit is at an angle ( this keeps the belt taught when a car is upside down, I think?). I had to remove this bit of the workings so that it could be mounted on the rear parcel shelf without locking up. The belt retracting unit was mounted on top of the rear parcel shelf. Just requiring two hole to be drilled through the leather directly above the captive safety belt nuts . On my 1969 Mk1 there are 2 proper mounting points adjacent to the boot light (under the centre of the parcel shelf. The bolts provided with the seat belts are the correct fit. The other end of the belt was mounted through the propshaft tunnel (required the rear seat squab and back to be removed and holes drilled. I used the bolts and strengthening plate that came with the belts). The straps with the buckles on them were mounted inside the cubbies that are on the right and left side of the rear seat. There are actually captive nuts in my cubbies ( presumably for front seat belts – because it is a late 69 car?) but I drilled through these and used some bolts and strengthening plates to mount through the wheel arch.

Others on the list have had the following to say on fitting rear seat belts:

1. I’ve fitted so-called “generation belts” with a slider to accommodate both adults and small children in the back. As far as I can remember there are no mounting points in the back, but pulling the rear seat cushion which simply pulls out you should be able to verify this. I think I drilled holes into the rear wheel well, and used the prescribed load spreading plate on the wheel side of the bolt. Similar for the diff hump. In both cases the hole is in the sidewall of the cushion “well”. The reel fits underneath the rear parcel shelf steel plate. I consider that this plate being welded to the substantial cross tube at it’s front edge, to the body at the sides, and bent to reinforce it at the rear edge, is good enough. You will have to make a small slit to let the belt through, make sure it doesn’t fray the belt or cut it under load. Use your own judgment as to what’s necessary in this area. Speaking for myself I believe it’s at least sufficient for children. The belt simply comes up from the seat well between backrest and cushion, so make sure the belt to be used has webbing on both sides of the buckle. The plastic coated stiff wire will make fitting troublesome.
2. I’ve just looked over my ’69 Mk1 FF and it doesn’t have mounting points, so I’d guess that yours doesn’t. The mounting points, when fitted, are in the back corners or the rear seat wells with a top mounting point underneath the rear parcel shelf, most easily viewed from inside the boot. I think that mounting points were fitted from about 1970.
3.I recently fitted Securon inertia reel seat belts to the rear of a ’74 Interceptor, so, with a bit of ingenuity, you should be able to do the same.
4.We fitted a belt for the rally. Standard accessory shop cheapo belt (he was only reserve navigator!) Take the back and squab out and drill through nearside rear wheelarch, trans tunnel and nearside rear c pillar (behind your ear!). Adjustable belt with central short stalk fits fine with big washers to secure to car and kept our man a back seat driver.