Chris finally gets around to fitting electronic ignition to the TR7 – the improvements are startling
The TR7 has broken down twice in the year or so I’ve owned it and on both occasions it’s been as a result of worn points and condenser. I believe that replacing them is straightforward, but on the TR7 the position of the distributor can only be described as lousy, obscured on all sides by the engine manifold, cylinder head and bulkhead-mounted bonnet release. In each case, these breakdowns resulted from attempts to ride my luck; ‘It’s an awkward job’, I thought, ‘I’ll put it off until next weekend.’ The next thing I know, I’m stationary in a layby on the A47.
A few weeks ago I decided that there wasn’t going to be a third breakdown and after taking advice from Simon at Robsport (01763 262263, robsport.co.uk) booked my TR7 in to be converted to Lumenition electronic ignition.
There are myriad benefits to electronic ignition (which I’ll get on to later), but my primary aim was to remove from the service schedule something I saw as being inconvenient – changing the points and condenser shouldn’t be as fiddly as it was proving to be.
With the TR7 once again in Robsport’s workshop, mechanic Jake began by positioning the piston visible with the oil filler cap removed at top dead centre, achieved by turning the engine by hand at the crank with a ratchet wrench and a chunky 38mm socket (I need to buy one for my tool set). He then removed the distributor from its sunken position in the engine bay and set about removing its innards.
The TR7’s distributor is a Delso unit with a rotor arm that sits on top of a disc – this is retained, with a mounting plate for the optical switch attaching to the breaker plate and a plastic ‘chopper’ (a fan-like disc with four tabs to disrupt the infrared beam being sent by the switch) attaching to the mainshaft, under the rotar arm. Breaking the beam is what triggers the external power unit to fire the coil – this module needs to be located in the engine bay, so there is some drilling required (Jake attached it to the inner wing in this case). This form of optronic ignition retains the distributor’s vacuum and mechanical advance mechanism, ensuring that engine timing is as per the original manufacturer’s specification.
With the Lumenition kit now in place, the final job for Jake was to replace the distributor and turn it by hand, using a timing light to ensure that it was in the correct position. It was then taken on a quick test-drive to make sure that all was working as it should, while I had a play with one of the cars Robsport had for sale – a Triumph Stag powered by a Ford V6 engine. Read all about it on page 57.
Leaving Robsport and heading back up the A1 to the CCW offices, I was amazed at just how much the Lumenition kit had improved throttle response, particularly at cruising speeds. It’d probably be overstating things to suggest that it’s improved performance, but the engine does seem to run notably smoother than it did before and is most definitely more comfortable at higher revs than it was on the old contacts breaker set-up. What’s more, on a morning the TR7 is now far happier starting. Before, the four-pot would churn several times before it awakened. Now it fires almost instantly.
I’ve been assured that I’ll see better fuel economy now too – I’ll let you know the next time I fill up whether there’s been an improvement, but even if I don’t see a difference, I’m still thrilled with the result.
Owned Since April 2016 MILEAGE SINCE LAST REPORT 429 TOTAL MILEAGE 100,547 LATEST COSTS £160 (Lumenition kit)
Back in the workshop, this time to be converted to electronic ignition.
can you see it? with the dizzy cap off, it’s obvious that there are few worse places to locate a distributor.
an optical switch and ‘chopper’ disc replace the points and condenser.