The tensioner mounts

I’D TAKEN THE Jaguar down to Twyford Moors for a clutch upgrade – pretty standard stuff, except that with an XK140 it’s an engine-out job. And an XK lump requires quite a degree of heavy lifting. So, with the engine removed, I casually asked Ian and the team to take a look at the lazy chain tensioner, as it’s apparently easier to get at the front engine cover with the engine on a stand.

Crikey! I didn’t realise that the engine had to be almost completely disassembled in the process. Head and sump removed; decapitated and disembowelled, if you like. Looking at this ‘work in progress’ photo, above, I nearly had a heart attack. But to these stout fellows in Clanfield, stripping a lusty XK engine is bread and butter, as it’s what they do day in, day out.

So, away with the old-style tensioner and in with the new: the preferred choice of Jaguar XK racing engine builders. As you see, it is a more robust and betterengineered piece of kit, made of phenolic resin, which costs £155 but requires quite a few manhours to fit. Should I have had this all done or left well alone? The engine in my XK has always run quietly and smoothly, so a timing chain rattle at start-up was never going to be acceptable. Yes, it had to be sorted out properly with this improved tensioner, which will ensure reliability and longevity.

As mentioned last month, the heavy, old-tech spring clutch is being replaced with an improved diaphragm unit, matched to the beautifully machined, lightened flywheel, and the whole lot is balanced as a complete unit. The clutch will now be operated by a roller release bearing and, even though it remains mechanical, it promises a lighter pedal action.

Lead mechanic Barry has spent time sorting out the linkages and bushes between the clutch and pedal to ensure it all operates as smoothly as possible, without the need to convert to a complicated hydraulic set-up. While this job is becoming bigger all the time, it’s certainly getting better.

THANKS TO Jaguar specialist Twyford Moors, jagxk.com, +44 (0)2392 570900.

Above and right State of stripdown following removal shocked Coucher, but made for diaphragm clutch, lightened flywheel and new, improved tensioner.