LIFE, SAID SOMEONE, is like an elevator: a series of ups and downs. No-one knows that better than the classic car owner, and the euphoria of owning my recently purchased 1968 Jaguar 240, as reported in Octane 245, had started to wear off by Christmas. In spite of much investigation and adjustment, the engine was still running too rich, and most outings ended all too soon in a return home accompanied by backfiring noises.
I managed to contact the previous owner, who had not used the car much in the past couple of years, and he said that, yes, the problem had occurred before and he had been advised that sooner or later the carburettors would need to be rebuilt.
There was no better man for that job than Jamie Gibbon, who has a lifetime’s experience of working on Jaguars. Now semi-retired, he remains much in demand but was willing to take on the challenge. The car was duly trailered to his workshop near Loch Lomond, which happens to be beside the premises of Brayon Classic Engineering, another respected name in the world of classic car restoration, so there was no shortage of expertise on hand. Jamie completely stripped down the carbs, then vapour-blasted and reassembled them with new jet assemblies and needles, throttle spindles, bushes, float needles and seats.
The later SU HS6 carbs have plastic floats with metal fulcrums, which are preferable to the modern all-plastic replacements, but setting up the float heights is a delicate operation. The carburettor overhaul cured the over-rich running but the spindle and body of the distributor also turned out to be worn, so a custom-built electronic one was fitted, with vacuum and mechanical advance matched to the car’s engine specification.
The Jag is now a pleasure to drive: the engine is much more responsive throughout the whole rev range, from low-speed pick-up in higher gears to more spirited driving using overdrive – and the fuel economy h
