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I have this problem with my car that the motor tries continue running for a couple of beats after turning off the ignition. This does not happen when the motor is cold/has not reached normal operating temperature. Now, according to what I have read this is likely caused by an ignition source other than the spark plugs, which have no spark after the ignition is off (supposedly). Books talk about plugs that get too hot or hot carbon igniting fuel vapours that remain. They also talk about ignition timing. I have swapped the plugs out with standard champion plugs that I use on all my minis without problems, the motor runs very well and smoothly otherwise.

I don't want to mess with ignition timing because this motor is the smoothest and fastest one I have ever experienced so I would be VERY surprised if something is wrong with any timing aspect of it.

Any suggestions what I should investigate or how to go about tracing the source of the problem?

Running-on seems to be quite common with modern fuels. I had a lot of trouble with my Moke after they got rid of unleaded here. Eventually I found a brand that sells a higher octane e10 (10% ethanol) fuel, which solved the problem. Otherwise, you quickly learn to stall it in gear when you shut it off.

Tim

I agree with Tim, I have a mildly tuned 998, it was no problem when 4 & 5 - star leaded fuel was available, with the enforced advent of unleaded fuel, in it's unmodified form it 'ran on'. Since then it has had 2 modified cylinder heads, highly polished to reduce the chances of carbon building up & glowing, alloy inlet manifold, LCB exhaust, cooler plugs, different timing settings (which only reduced performance). Nothing made any difference. I then fitted an MG Metro anti run on valve to the inlet manifold. Job done! The problem is cured.

I never had any problems with any of my Mini,s .

They are 3 different engine types / carb setup =
1275 MG Metro engine, mildy tuned with a single SU HIF44.

1380, with a twin 45 Weber on a 6" Oselli intake.

and the JanSpeed runs a twin Dellortho (Lotus item)

I run them all on Shell V Power, and no additives.

and all behave 100% OK.


And to the ones, that have a Mini with this problem, you MUST have the car in gear, when you turn of the ignition, and release the clutch, at the same time as you turn the key, so you force it stop, becourse the engine is running backwards this means WITHOUT oilpressure = NOT GOOD.

JC T ONE wrote: And to the ones, that have a Mini with this problem, you MUST have the car in gear, when you turn of the ignition, and release the clutch, at the same time as you turn the key, so you force it stop, becourse the engine is running backwards this means WITHOUT oilpressure = NOT GOOD.

I'm not sure Jens, I've heard this said before but there are two things that contradict it, firstly the engine never stops, so it can't change direction, but secondly if I don't put my foot on the brake the car lurches forwards, not backwards.

Tim

If you want to stop the engine running on when you turn the ignition off just turn the engine off with the clutch pedal down. Not a cure I know.

JC T ONE wrote:I never had any problems with any of my Mini,s .

They are 3 different engine types / carb setup =
1275 MG Metro engine, mildy tuned with a single SU HIF44.

1380, with a twin 45 Weber on a 6" Oselli intake.

and the JanSpeed runs a twin Dellortho (Lotus item)

I run them all on Shell V Power, and no additives.

and all behave 100% OK.


And to the ones, that have a Mini with this problem, you MUST have the car in gear, when you turn of the ignition, and release the clutch, at the same time as you turn the key, so you force it stop, becourse the engine is running backwards this means WITHOUT oilpressure = NOT GOOD.

..jens, i see u use shell v power,any higher octane rated fuel without the use of additives should do the trick,..optimax or for that matter any of the major fuel suppliers are now offering better qual fuel should assist the running of converted heads..ill always use better qual fuel where i can get it.. thats running twin h4,s,janspeed inlet manifold on a 1330....but !! i dont notice any appreciable diff.. getting the air/fuel mixture right is so fiddly but crucially important,thats why rolling roads are such a good idea to get yr car set up properly....

Lord Croker wrote: I then fitted an MG Metro anti run on valve to the inlet manifold. Job done! The problem is cured.

I would agree with Croker, if all is well with the engine and is set up right this valve takes all hint pre ignition away. I use one.

The MG metro had it fitted as standard for a reason

Not a solution to the problem,but my rallymini had it too.
Running a weber ,i turned off the ignition and put the throttle open.
It will get too much air and will stop.The anti run on valve does the same.

abri wrote:I have this problem with my car that the motor tries continue running for a couple of beats after turning off the ignition. This does not happen when the motor is cold/has not reached normal operating temperature.

Do you use a kenlowe fan?

André

I use a standard Mk1 Mini 6 blade fan for hot weather.

My temp gauge goes all the way up past the red when earthed to the block so it is working.

Hey Abri

My 1380 runs on like a beast - i dont think it would stop if i left it..... until the fuel in the float bowl runs out that is.

My fault entirely though, I bought the hypatecs from Auz, assumed, because they looked almost identical to our SA GTS (innocenti) pistons that the comp ratio was 9.75-1. unfort when i redid the calc after i picked up the horendous pinking when the new motor was up and running, it turns out they are over 11-1 with std head and deck height.

And the 95 octane unleaded or even the 95LRP just isn't good at those levels of compression IMHO.

i sorted out the pinking by setting the static timing at TDC, but it will still run on if i dont keep it in gear and let the clutch out as i turn off the ignition.

Been running that way for 3 years now, and for the last 3 weeks i used it every day for the work commute through the usual rush hour traffic from Pinetown to Durban.

So i wouldn't stess to much about it.

Sean

www.mini-kzn.co.za

Anti Run on valve works for me.
As fitted to MG Metro and Rover Cooper Carb Mini's:
http://www.moss-europe.co.uk/graphics/u ... TN127Z.pdf

Thanks for the replies and advice guys. I think I'm going to try the throttle action while turning off the key. It makes sense that it would work similarly to an anti run on valve. I've set it one flat richer to help it run a bit cooler too. Will see if it helps once it stops raining here

Ok guys, an update on the state of affairs with my problem. I have spent the biggest part of the last two days making sure everything else is set up right so as to try and identify what the possible cause might be. Before I go further, I should say that while the car runs smoothly at higher rpm (2000+), it does not idle smoothly.

I spent a lot of time centering jets, messing with mixture, synchronizing carbs, setting idle speed etc, so I am confident the carbs are fine. The throttles are not worn.

I installed new points and condenser and set the gap correctly.

I played around with the static ignition timing by loosening the dizzy and turning it very slightly in both directions to check the effect. I did not set it according to the book or check that is was to begin with. I just turned it slightly from where it was.

I also tried the advice of pushing in the accelerator pedal when turning the ignition off after a run.

Results:
Still idling unevenly and still running on ( f%#K!!!)

The timing adjustment made the exhaust tone more uneven in both directions and I could feel a substantial warming of the exhaust gas with timing retarded. (keep in mind I only turned it by about 1-2mm either way).

I have a question regarding mixture - after a short but high speed run the plugs were all nice and brown. I was wondering, assuming my needles are standard for a 1275 S, is there a correct measurement distance between the top of the jet and the "bridge" in the carb body? My other car has the jets set to 2mm below the bridge and it runs smoothly, but it is a 1293.

I have now swapped the dashpot/needle/piston assemblies from a very recently rebuilt set of carbs into the place of the set that were on the car. Idling has slightly improved, but running on continues.

The anti run on valve suggestion was noted, but I wanted to try to sort potential causes out before I slap on a band aid.

Thoughts?

Anti-run on valve is not really a band aid, the factory started fitting them in later years for the same problem, probably caused by modern fuels. With a longer hose fitted you can hide it from view if you are worried about keeping original underbonnet looks.

Tim wrote:Running-on seems to be quite common with modern fuels. I had a lot of trouble with my Moke after they got rid of unleaded here. Eventually I found a brand that sells a higher octane e10 (10% ethanol) fuel, which solved the problem. Otherwise, you quickly learn to stall it in gear when you shut it off.

Tim

We run our race car on 105 octane no ethanol leaded fuel, and it still runs on, just drop the clutch to stop it.

regards

Eddie

I run my racecar on 98 octane fuel with 11.9:1 CR and it doesn't run on....why?