heatherdale Posted May 27, 2004 Report Share Posted May 27, 2004 HI All After a run with the engine up to temp when i turn off the ignition the engine carries on running for a few seconds. any ideas why and how do i stop this (car runs on carbs) thanks paul Quote Link to post Share on other sites
marvmul Posted May 27, 2004 Report Share Posted May 27, 2004 On some engines, it is difficult to cure this problem. Sometimes the problem is solved by tuning the carbs : if the trottle valves (butterfly plates) on your car are a little openend when idling, in order to prevent stalling, you can lower the jet (=more fuel) and give more static advance : then it is possible to unscrew the trottle adjusting screw (= the trottle valve is more closed) and to lower the idling rpm. Did you make changes on the ignition/carbs recently? Quote Link to post Share on other sites
Guest ron Posted May 27, 2004 Report Share Posted May 27, 2004 Mine used to do this quite a lot when I had the low compression US cyl head and Strombergs but since I changed to the high compression head and SUs it has stopped. It might also be something to do with petrol quality because my MG does it sometimes and other times it's OK. Ron Quote Link to post Share on other sites
Richard Crawley Posted May 27, 2004 Report Share Posted May 27, 2004 When lead free, high benzeene fuels were first introduced even modern cars running carbs had problems & most manufacturers introduced some form of electronic fuel cut off valve to prevent run on, with varying degrees of sucess. This was only really eradicated when they all switched to fuel injection. Not very helpfull, I know but this doesn't happen with a PI! Quote Link to post Share on other sites
rayjones Posted May 27, 2004 Report Share Posted May 27, 2004 Ford used to fit a solenoid operated valve, which dropped out when the ignition was cut, and let air into the manifold, to stop engine run on. One of the reasons for it happening was that engines were tending to run hotter as lean burn characteristics were being developed to reduce emissions and improve fuel economy. Ray Quote Link to post Share on other sites
jean Posted May 27, 2004 Report Share Posted May 27, 2004 Paul, I have the same problem with my TR3, when the engine idles around 1000rpm. I noticed that there is some play in the throttle linkage. Positioning the foot under the throttle pedal and giving it a little pull before switching the ignition off cures the run on. A more drastic procedure is putting it in a gear, foot on the brake, releasing the clutch and killing the run on. Jean Quote Link to post Share on other sites
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