SPITFIRE PUSHROD
Handy Howie
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I was driving home from work on the A19 in my 1971 MK4 Triumph Spitfire, when there was a sudden decrease in power accompanied by a loud backfiring noise coming from the engine.  I knew there was a lay-by coming soon and managed to drive to it.  I lifted the bonnet and could immediately hear the noise was coming from one of the carburettors.  I presumed that something must have gone wrong with one of the inlet manifold valves stopping it closing, possibly either a damaged valve or a broken valve spring.

I called my wife and she travelled over and towed me home using one of the Land Rover Discoverys.  When I got home I couldn’t resist having a look to see what had gone wrong.  Lifting the rocker cover off revealed what turned out to be a simple problem.  One of the pushrods had managed to jump out from the rocker arm adjuster.  I had been meaning to adjust the valve clearances for some time but had not got around to doing it.  All the clearances needed adjusting, but I was surprised that the pushrod was able to disconnect with the small amount of free play in the rockers, I had to undo the adjuster a lot to get the pushrod back in.  Rather than it being an inlet valve at fault, it was an exhaust valve that was permanently closed, this meant that the only exit for the burnt gasses was back through the inlet valve when it opened.

After adjusting all the rockers, the engine is now ready for work again tomorrow