Plug and play
Success at last! Regular readers will know that one of the TR7 pop-up headlights has been performing a little comedy routine, flipping up and down at will. Having previously worked through the simpler and cheaper potential causes – cleaning electrical connections and replacing relays – this month I had to bite the bullet and replace the actuating motor. With a tried and tested secondhand motor sourced from TR7 specialists S&S Preparations ( www.ss-preparations.co.uk), it was quickly fitted, the actuator rod adjusted and this time both headlights worked perfectly.
TR7 headlight finally fixed, most of my attention since has been focused on the TR6. Having fitted the Amethyst mappable electronic ignition at Aldon Automotive a couple of months ago (see CM 211 for full details), I have at last found time to connect the vacuum advance and try some adjustments to the ignition timing map. As standard, fuel injected TR6’s don’t use a vacuum advance, although conventional wisdom says this feature improves tickover and fuel economy, so I was keen to find out what effect it would have on my ‘6.
The vacuum connection was made by cutting the hose from the inlet manifold near the PI metering distributor and inserting a brass T-piece. A Mini vacuum advance pipe completed the link to the Amethyst’s vacuum sensor – easy. An email consultation with Amethyst designer Kevin Jones suggested that a modest advance of 10 degrees at 14” Hg vacuum could be a good starting point, with no factory specification from which to work. In the event I was a bit more cautious and tried 8 degrees. With the engine warmed, I plugged my laptop into the Amethyst, set the required vacuum advance and
The ‘6 is just so responsive – it’s a real pleasure to drive
hit the ‘Enter’ key. The tickover speed immediately increased by about 100rpm, so I tried Kevin’s suggestion of 10 degrees and was rewarded with another slight increase at tickover. A little tweak of the air bleed screw that controls tickover on the Lucas PI system and the engine settled to a rock steady 800rpm.
Saving new ignition maps using the Amethyst software is straightforward, so I clicked ‘Save’, unplugged the laptop and went for a test drive. The TR felt great, too. The engine pulls smoothly almost from tickover and right to the 5500rpm redline, with response in the 1000-2000rpm range as clean as a modern EFi equipped car. At higher revs the engine is as strong as ever, but it’s the lower everyday driving range that’s improved the most. Time will tell if economy is better, but I’m really not too bothered, as the ‘6 is just so responsive – it’s a pleasure to drive.
Lack of time when the Amethyst was fitted also meant that we left the ignition wiring in an untidy state. I will gather all the additional wires in ribbed black plastic trunking to tidy the engine bay (I recently discovered this useful stuff is called ‘convoluted conduit’ – good to know when searching online). This job will have to wait until next month, however.
My final task was to fit the TR6 with new boot trim panels, bought on special offer at the TR Register International Weekend last summer in order to replace the existing dog-eared trim. All went in without too much difficulty, but the new panels didn’t seem to fit quite as precisely as the originals. A little trimming of edges and a couple of extra self-tappers to hold adjoining panels together resulted in a neater job.
Next month, I must continue the ongoing saga that is the TR7 electrical system, getting all instruments and electrical accessories working reliably. Tidying the TR6 ignition electrics will be child’s play by comparison, so I know which job will be done first.