Car runs on a bit, after turning off.

[Leeboo]

Hi guys,

When I switch off the engine in the Nova after its been on a journey (when the engines quite hot), it sort of revs on lumpy for a second, literally 1 or 2 seconds, and then dies. It does not affect how the car drives and performs. I am just curious as to what causes it. A friend said it might be carbon deposits or something? Its a 13S carb engine.

Cheers.

[meritlover]

carbon deposits on the tips of the valves and or combustion chamber, wrong grade of plug, or too high compression ratio.

dont encourage it, you can shear crankshafts by running on.

[burgo]

timing to far advanced i think it is can cause this also

[Leeboo]

Thanks meritlover. It doesn't do it all the time, just usually after a longish journey. I was thinking of firing some of that redex stuff through it.

Yeah Burgo, I had the timing set, and the man said he set the timing slightly advnaced, thinking it MIGHT give a bit more power. I have since been told that advanced timing doesn't make any difference to performance on a std engine. You reckon its worth getting the timing set again then?

[burgo]

advancing the timing makes ****e loads of difference imo. i set my loon correctly and it hardly moved. so i advanced it by turning the dizzy back by about 10mm and it makes it run so much better

[meritlover]

timing advance may give an increase in power but a drop of in torque as the power just moves up the revs. but low down there is poor combustion.

as burgo man says, this can cause the problem as the plugs and combustion chamber are running hotter and cause the fuel to ignite after the ignition is de-energised.