Fishingfalcon Posted September 1 Report Share Posted September 1 Hi just got myself a wonderful 1974 MkIV Spit ...all going great but last couple of trips when I come to a stop the engine revs at 2000 before very slowly dropping down to idle. Twin 1 1/4 SU's. Checked cables, return springs and dampers all good. Is this a case of carbon build up so needles not dropping down? Would appreciate any advice please. JoN Link to comment Share on other sites More sharing options...
Steve P Posted September 1 Report Share Posted September 1 Could be balance between the 2 carbs not quite right, or air getting past the butterflies, also butterflies the wrong way round or not closing properly. S 1 Link to comment Share on other sites More sharing options...
Fishingfalcon Posted September 1 Author Report Share Posted September 1 Thanks Steve I suppose what it odd is everything was fine and I have changed nothing. Will get the airbox off and have a proper look. Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 1 Report Share Posted September 1 check for air leaks in the breather system oil filler cap , rocker gaskets etc sticking air pistons will upset running but in general will not have silly effects on idle speed variation What filters are fitted ? make sure the vent holes in the filter face are not obstructed Pete 1 Link to comment Share on other sites More sharing options...
Richeee Posted September 1 Report Share Posted September 1 I would also just check the linkage and the carpets. Normally it can stop the pedal going down. But check the basics. 1 Link to comment Share on other sites More sharing options...
Fishingfalcon Posted September 11 Author Report Share Posted September 11 Just thiught I would update. Removed carpet, cleaned carbs, checked linkages etc. Have no idea which made the difference but problem now sorted 🙂 Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 11 Report Share Posted September 11 Ha the cheap and silly are the best problems to solve pleased its all ok now Pete Link to comment Share on other sites More sharing options...
Iain T Posted September 11 Report Share Posted September 11 4 hours ago, Fishingfalcon said: Have no idea which made the difference My money is the carpet. I had a Spitfire 1500 with a runaway engine which was all down to the carpet catching on the accelerator pedal. Iain Link to comment Share on other sites More sharing options...
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