Pyjamas in the Tailpipe

Funny one this. I'd been moaning to the redoubtable Edward that the Rover exhaust was very noisy - principally because the previous owner had fitted a tail pipe from a 3.5 litre P5, which has two exit pipes on the rear muffler.

The 3 litre P5 should have a single exit pipe, and run very quietly (silently according to the contemporary test reports).

Incidentally, despite the new plugs, plug caps and leads, there was still a bit of a misfire too - probably carburetor-related.

Edward rang me and pointed out that the internal plumbing of the rear muffler/silencer box was simply 'one pipe in and two out' - so if we blocked off one of the pipes, I might (effectively) end up with a more-or-less standard system. "Try it with a rag first, to see how it runs, then if it is ok, we can simply weld in a metal disk to block the pipe." He suggested the right-hand pipe for some reason and said something cryptic about the old Rover engines liking a bit of 'back pressure'.

Always ready to fight the dark forces of automotive truculence with unexpected weaponry, I packed a once-faithful (and appropriately empty) pyjama leg into the right hand tail pipe - packed it in as hard as I could, then cut off the excess.

After starting, the car did indeed run quietly. And very smoothly. I took it up the street and back with no signs of trouble.

This was 10 days ago. The pyjama leg is still as well packed in as ever after over 300 miles - so no pressure is forcing it out. The engine is now as quiet as it probably was when new - thanks to the new plugs, leads, etc - and the exhaust is really quiet too - even my wife commented - and she rarely shows more than a passing indifference (understandable really - once she shows any interest, I start talking cars...)

But there are two more surprises. When I got the car, it was doing woefully worse than its original 17 mpg (imperial) or about 16 l/100km. I could tell. I was too scared to even measure the consumption, I just knew it was horrific.

However, after the various improvements (valve resetting, plugs, leads and the pyjama leg) I felt more confident.

You see, the remaining misfire all but disappeared (first surprise), and the old girl now pulls happily and cleanly from about 15 mph in top gear, so driving has become more relaxed. The engine is 'quantums' smoother and quieter - and I seemed to be filling up less.

SO I measured over about 250 miles (400km) of a lot of freeway and some urban driving - my normal stuff (see pic). I was very pleasantly surprised (second surprise). My 1.7 tonne, 120 hp Rover and I were returning a bit under 23 mpg (still imperial) or 13 l/100kmh, by my calculations.

All things considered, pretty good. A case of my pyjamas helping to save the planet. I know it isn't VW Golf diesel territory, but then I am helping the planet by not causing yet another unnecessary new car to be manufactured - which, by all accounts, puts me way ahead of the Golf owner!

And anyway, I don't drive as far as he does...

Speaking of saving the planet - here is a Rover P4 (actually about the same age as my P5) awaiting some resuscitative surgery from Edward before being recommissioned. I like these cars - used to have one in the UK. This one is nothing to do with me - but I thought I'd show you a picture

Happy Motoring!