WaringstownTR7s.co.uk

Converting to Lumenition electronic ignition
(by John)

This article refers to the installation of Lumenition electronic ignition in a standard 2.0 TR7 engine with an AC Delco Remy Distributor.

There are 3 manufacturers out there providing electronic ignition conversions for the TR7 2.0 – Piranha, Aldon and Lumenition. In researching these options, I posted a few messages to forums and the consensus was that Lumenition, although being more expensive than the others, was the most reliable and the best quality. In saying that, Aldon seems very reliable and the only negative thing anyone said to me was with reference to the Piranha’s long-term durability. The Aldon Ignitor, uses magnets to function, whereas the Piranha and Lumenition units both use optical sensors. The Lumenition power module seems to be that bit more sturdy than the Piranha unit, using an alloy casing in place of the Piranha’s plastic one. After fitting our Lumenition kit, I must say, I was very impressed with the quality and sturdiness of the components. I bought my complete Lumenition kit (power module, optical pickup & fitting kit – i.e. everything you need) for around £110 from Robsport who price matched Rimmers during a sale time.

Pic of optical pickup and power module

Step 1: Check that your ignition coil uses a ballast resistor

Apparently if you poke around under the dash somewhere, you’ll find the ballast resistor! But… here’s how to use a voltmeter to test whether or not you’ve (a) got one and (b) it works. I found this advice on Autocar Electrical Equipment’s website, which has a comprehensive article on fitting Lumenition (well… they do make them!). If you do NOT have a ballast resistor in the circuit, the current is too high for the Lumenition power module & you’ll blow it – so make sure!

Note: This test involves the use of a voltmeter suitable for reading voltages from 0-15 volts.

1: Disconnect the lead or leads connected to the negative (-ve) or earth terminal of the coil.

2: Connect the voltmeter between the positive (+ve) or B terminal and a negative or earth point on vehicle.

3: Switch on the ignition.
The voltmeter should read battery voltage.

4: With a suitable length of wire, connect the Coil Negative (-ve) to an earth point.

If the voltage on the voltmeter remains at battery voltage there is no ballast resistor present in circuit.

If the ballast resistor is present in the circuit, the voltage will drop to approximately 6-7 volts.

5: Immediately switch off ignition.

Note: Never leave the earthing lead connected to the coil for more than is required for the test, as continued connection will result in an overheated, damaged coil and a drained battery.

This test is straight forward enough. The only problem I had was that I wasn’t sure which terminals on the coil were the +ve & -ve. After a bit of messing around I soon got the result described above – where the voltage drops a few volts on turning on the ignition.

Step 2: Preparing to remove the distributor

Given the position of the distributor – the only sensible option is to remove it, fit the Lumenition conversion and then replace it in the same position.

After removing the fresh air scoop, distributor cap & HT leads your 1st task is to make sure that your engine is sitting with the No 1 piston at Top Dead Centre (TDC). To do this, stick the car in gear and rock it until TDC is achieved. There are 2 ways to know when you are at TDC.

1. The rotor arm will point towards the rear manifold bolt as shown below

or

2. Look at the markers on the pulleys – when they line up, no 1 is TDC.

Rotor arm diagram
Rotor arm pointing towards rear bolt

Pulley markers
Markers on pulley

Once you have done this it is useful to take a bit of correction fluid (Tippex to you & me!) and mark the position of the distributor exactly. This is so that when you refit the converted distributor, the timing won’t be far off.

Now remove the advance unit pipe. Your next job is to remove the 2 bolts that hold the distributor in place. The workshop manual refers to service tool S349, but our friend Hugh from the TOC created his own by shortening a ring spanner. The room around these bolts is so tight that there is no other way.

Shortened spanner for distributor removal

Distributor after removal

Step 3: Out with the old & in with the new!

Time to throw out the old points & condenser!

The Lumenition fitting kit instructions are clear and easy to understand. After removing the distributor you need to withdraw the centre shaft. To do this, you need to hammer out the roll pin that keeps the drive gear in place. A nail will do the job – or anything small enough to tap the pin out without damaging anything.

Hammering out the roll pin

Once you have the pin removed you can withdraw the centre shaft. Don’t lose the washer!

Next, you remove the points & condenser. After this you have a 2 part process.

1. Fit the mounting plate & optical sensor
2. Fit the chopper (breaks the light beam – has 4 legs, 1 per cylinder)

Rather than just repeating what the Lumenition instructions say… I’ll show you how things looked after fitting the optical sensor and chopper.

Pic of optical pickup on mounting plate
fixed to the distributor in place of points/condensor

Pic of chopper - note the 4 legs which will
break the light beam from the optical pickup

You can now reassemble the distributor unit, refitting the drive gear and pin, not forgetting the washer. You can now route the optical sensor cables through the exit hole, using the grommet supplied with the fitting kit. It is worthwhile testing that the cables do not restrict the vacuum advance. To do this, just suck the pipe coming from the advance unit (see photo above). You should see clearly that the timing advances freely. Double check this before refitting the distributor.

Step 4: Refit the distributor, mount & connect power module

Refit the distributor – no surprises here – just do what you did before, except in reverse order. You’ll now need to mount the Lumenition power module somewhere safe and cool. In basic terms, the power module is an electronic device that takes signals in from the optical sensor (now in the distributor) and tells the coil when it’s time to spark. We chose to put it in the extreme corner of the (RHD) driver’s side bulkhead – tucked away out of sight and far away from any sources of heat. 2 self tappers hold it in place.

Power module tucked away (before tidying the cables!!)

A fitting bracket is available which allows the power module to be fitted beside the coil. It requires no drilling and I bought one with the kit (at an extra cost). We chose not to use it in the end because it made the module overly visible and we had our doubts about mounting the module so close to the coil.

Pic of fitting bracket

You now need to connect the wires coming from your distributor, to the power module. The fitting kit includes a connector block, which takes the3 wires coming from the optical sensor which is now inside your distributor. Following the Lumenition instruction sheet, using pliers, fit these 3 wires into the plastic connector block until you hear them each click into place. Position 1= Red , 2 = black, 3 = Blue. When you’ve fitted these wires into the connector block, the block then clicks onto the equivalent connector on the power module. Jumping across to the power module fitting instructions, you’re then left with a few wires to connect up to the coil. The red wire goes to the fuse box, the violet goes to the –ve terminal of the coil.

At this point DOUBLE CHECK THE WIRING!!! The instructions are very implicit here – do NOT connect the violet wire to the +ve supply or it’s good-night. The ONLY wire to get a +ve feed is the red wire. Screw up here & you’ll blow the power module and invalidate your warranty

Step 5 – Cross your fingers & test it

Once you are sure that all wiring is good and the distributor is back in its EXACT place (refer to your tippex marks), you can start the engine. In my case, I was amazed. Firstly, the car fired up super quick. Noticeably quicker – and then there was the tick over. My engine would have shaken about a bit at idle, but now settles down to a nice steady beat with minimal vibration. The car is also transformed on the road. Power is definitely up and more importantly, the car is smoother to drive.

After establishing that all was well, we went on to check the timing with a strobe. The fact that you have kept your distributor position means that this is not vital – but we felt that the car ran that bit more smoothly with a slight change to the timing – perhaps due to the stronger sparking.

Verdict:

Unless originality is your top priority, I’d whole-heartedly recommend this modification. In saying that, the distributor looks no different and your power module can be well hidden as in our case. The TR7 distributor is in such an awkward place that you will enjoy no longer having to adjust your points. Add to this the performance improvements and you have what I can only describe as money well spent!

We’d like to say a BIG thank-you to Hugh from the TOC – we couldn’t have done it without you!

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