Page last updated 27 October, 2009



Technical Questions - Ignition & Charging
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Date asked

Question Answer

10th October 2009

By Ed VanVoorh

Is there a trick to reinstalling the distributor hold down bolt? I've
> spent 3 hours and the @#$$$#%$%^& thing is still not back in!

78 3000S USA


Follow up by Ed on 10th Oct

Thanks for the reply. a 1/4" drive worked, plus a liberal dose of ill wishes on Ford and the motor's designer.
The major problem is getting the bolt started. While we are at it, my car has a "stumble" upon hard acceleration between 2000-2500 rpm. Do you have any experience with that?

Follow up by Ed on 26th Oct

I am wondering about working with the timing a bit. With the air injection, etc. removed, I may be able to tune my way out of it. I did check the carb's internals and all seems to be clean. I run two fuel filters to prevent junk in the carb and try to keep the throttle plates clean.

It's probably the socket extension you are using fouling on the inlet manifold (1/2" or 3/8" can foul depending on manifold type), the tight access means the socket position is tilting the bolt so it doesn't go in straight. If you have one try using a 1/4" extension bar with a wobble drive end - as the smaller diameter extension means more room to line up, and the wobble drive end allows the socket to tilt as required.







Follow up by M-Fix on 26th Oct

The hard acceleration "stumble" could be due to the carburettor acceleration pump diaphragm becoming perished - although a leak would normally appear if this were the case. You should also check the accelerator jets in the carburettor as these can become tarnished & clogged over time - requiring removal & cleaning with compressed air. With the engine off, remove the air filter housing and manually open the throttle fully while looking into the venturis on the carburettor - a jet of fuel should spray into the inlet manifold. Any blockage will show up as either a drip of fuel or none at all. If this is not the cause then you may find the one of the main jets are blocked, or there is another problem e.g. ignition - perhaps faulty condensor/ignition coil etc etc.

19th June 2007

By Rob Stanway

I have an early 1600M with questionable wiring. I’m trying to sort a few things out. Can you tell me what the voltage stabiliser should be and the ballast resistor for the coil. Also I’ve be told that there are coils that are ballasted and therefore need to extra resistor, is there a way of checking?

Follow up from Rob on 20th June

The + of the coil is only fed by 1 wire that does go through a resistor. I’ve not traced the wire back from there yet. (the car did struggle to start when cold, but that’s another story!) My rev counter hasn’t been wired in properly. So I ran a wire from the – of the coil back to the rev counter, and connected the other terminal to common green feeding the rest of the gauges on the dash. When I did this the engine spluttered and stopped, but the rev counter moved a little.

My thinking was to run new wire to the coil as in the diagrams from your site and to the rev counter to see if I could make things better.

Do you know which terminals are for what on the back of the rev counter? There are 2 bullet connectors, one above the other, and a shovel connector to the side of them? I currently have the top bullet to be + the lower – and as yet am confused about the shovel.

The voltage stabiliser as you may have read is for the steadying of gauges that would otherwise be useless (i.e. fuel level and water temperature usually). I have used a stabiliser as fitted to old minis sucessfully, and you can see the way they are wired into the system using the downloadable wiring diagram on the website (just found photos weren't working so updated the page to make it complete again) only viewable in the members area but you are a member!

The ballast resistor starting system differs from a standard 12V coil system using the following method:

The coil is normally around 9 Volts on a ballasted system, and uses this lower voltage to boost the spark at starting (due to power loss caused by starter motor drain in cold conditions). When the ignition swith is turned to the start position, the power to the coil goes directly to the coil, hence boosting the spark. At all other times the supply to the coil is fed through the ballast resistor - hence the need for a lower than 12V standard coil. This is also an advantage in that the coil runs cooler due to the resistor generating a portion of the heat normally found in the coil, and the coil is therefore able to provide a better performance. Check your coil feed wire (on the + side) to see if it goes to a white ceramic item mounted near the coil - if so that is your ballast resistor.








Without a second feed wire to the coil + terminal, you will find the car runs ok using the ballast resistor, but on starting you won't get the extra boost the whole system is intended to provide. You will need that second feed to run from the starter solenoid so you get the full 12V to the coil only when starting (i.e. bypassing the resistor). An alternative would be to fit a 12V standard coil, and remove the ballast resistor altogether - just you won't get the boost for starting at colder times of the year - not always a problem for TVRs that are kept locked up for winter anyway!

As for the connections - take a look at this link:

It should be the same as yours. Click on the photo and it shows a larger photo but the wording isn't that clear & doesn't make complete sense. Looks like the bullet connector marked *1 is the switched live (i.e. live when ignition on), *2 is the coil pulse wire from coil - terminal. *3 text says "Switched Live, T Power, if no antitheft switch *3 (spade terminal) can be connected to *1". Perhaps you could try looping the supply wire from *1 to *3 but do so at your own risk!! There is another spade terminal on the body for the earth wire, plus other markings on the photo show lamp wiring etc. Lastly I am assuming you have standard ignition, not electronic? Electronic ignition can be tricky to set up on earlier tacho's (if gauge pre 1974 type).

27th April 2007

By Aiden McConnon

Having a few electrical gremlins with my M at the moment (surprise surprise). The ignition light is staying on and the battery is not charging. Thought it would be the alternator, so had that re-built, an found the rectifier had gone. It seemed to cure it for about an hour, and now the same problem has come back, but more intermittent this time, so probably bad connection somewhere. What do you think I should be looking for?.

I would first check the battery - it may have a bad cell. Also check battery terminals are tight, earth to chassis is good (full continuity using an Ohm Meter). Best way to test battery is using a drop tester - available from may places - see link:

If all is ok here, suspect the wiring to the alternator or even perhaps the recon alternator has a fault (unlikely but still a possibility). Also check wiring to ammeter (if fitted) as this can cause a charge fault. Please see downloadable wiring diagram in my Technical manual for info.

19th September 2006

By Steve Lewis

I have a 3000s which has recently developed a severe misfire when the car has driven approx 25 miles. I suspect the coil may be at fault as it seems quite hot. The present coil is the original Commercial Ignition V8039 with 3 terminals plus the HT lead.I cannot seem to be able to find a new replacement. The type of coil you require depends on whether you have the ballast resistor fitted or not. For this ballasted system the coil is different, and gives 12 Volts staring, but 6-9 Volts running. This is so that when turning over th eengine a full spark is fed to the plugs - without it the spark is weaker due to the load on the starter.

Any motor parts supplier shoud be able to provide you with one (e.g. halfords) - simply see if you have a ballast resistor fitted to the ignition (will be somewhere near the coil and wired in to the + side of the low tension circuit (small wires to/from the coil). It sill probably be a white ceramic block with a metal bracket, or sometimes like a silver cylindrical relay.

5th July 2006

By Paul Filippucci

I want to up grade to a 60 plus amp. alternator, my original one is about ready to die, I am going to go with electric cooling fans on rad. rather then the one attached to engine plus hopefully will be instaling an a/c unit in car sometime in future.

So with orginal wiring how many amps might I go up to? Is there anything else I need to change on car.

The current alternator was rewired internally so that the NB brown with blue strip is not attached. The new alternator that I can have built to my spec (ie amps) has one post to attach brown and brown yellow so should the NB be attached to it also? Any suggestions would greatly help me in deciding what to do.
Not sure on the original wiring max. amperage, as the wiring could vary from vehicle to vehicle
depending on if it has been modified from that fitted originally. I would think that it should be
able to cope with any output alternator, but if in doubt change the wiring N from the alternator to
the main bulkhead terminal to a thicker gauge, and the NB wire also.

As for your second question, it may be wise to attach both wires to the terminal to allow the current to pass to the loom without overheating - one wire could be overloaded if all the consumers are on at the same time (eg heated rear window, headlamps, heater fan, cooling fan, wipers etc etc).

27th July 2005

By Victor Svekolkin

I would like to change my Essex 3 litre V6 to electronic ignition. Do you know a good supplier of the necessary kit to convert my distributor or a straight replacement? Reliability and performance from an old car is my aim so advice is greatly appreciated. I will shortly (hopefully in the next 2-3 weeks) be stocking such an item for sale on the website. In the mean time if you need one ASAP try

6th June 2004

By Paul

When I time my TVR, I remove and plug the vacuums line to the distributor, the recommended idle speed should be set also at this time, in which it would go up when I reattach the vacuum line or do I set the timing put the vacuum line back and then set the idle.
Yes you're right, set the timing with vacuum pipe disconnected & plugged, then reconnect, then set idle.

26th February 2004

by Tony Kilbee

Could you please let me know what the recommended plug and points gaps are?

On the Ford V6 Essex the plug gap is 0.60mm (0.024in), and the points gap is 0.64mm (0.025in) - or 36º to 40º Dwell angle.