Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Engine keeps on running!!!

But Edd China is a good mechanic. Isn't he? Isn't he?

Yet another twopenneth coming up..........

Many years ago I rallyed a well tuned mini and this had a tendency to run on. In fact when the ignition was switched off pressing the accelerator pedal kept it going continuously.
I knew the engine was clean and the timing, etc was correct because all the performance was there and it was stripped almost weekly. So......conclusion was that with the high compression, wild cam, big carbs and loads of fuel going in, it was the fuel continuing to be sucked past the throttles on switch off that caused the "problem".
The moral of this tale being don't rush around in a panic changing things that aren't "broke" as (in my opinion)running on is a passing nuisance and the engine can handle it.
Finally.......is there fuel going into the engine that shouldn't, when the ignition is switched off? I have little or no knowledge of ECU's, etc but that is the question I would ask.

simon

I also had a well tuned cooper s. It had a slightly higher tick over to overcome the lumpy cam and would always run on when switched off. The answer was to put it in top gear and ease the clutch out while switching off. Nothing to fix, just a symptom of high compression.

The OP has a 1982 4/4. No ECU and 32/36 DGAV (or a DGV and a manual choke).

A carburettor engine always has fuel, even if fitted with an electric pump as the float chamber has enough fuel to propel the car 100 yards. Shouldn't matter with a petrol engine as the key turns the spark off and petrol engines should then stop.

Can't see inside the engine, but basically, something is acting as an ignition source. Carbon build up is almost certainly the issue. Known not unsurprisingly as dieseling.

No idea what the car was, but one Ford had the problem so much they made an 'anti-diesling valve' that admitted air to the cylinders when the ignition was off. Engineering wise, complete and utter bodge in my book.

Gents

I fitted the new plugs and took her a spin this morning (flying jacket on as it was spitting and I really cant be fagged putting the roof up for a short spin). She actually performed very well and I think acceleration was crisper than normal (that or the double espresso was kicking in). When I got her good and hot and turned the ignition off she still over-ran (dieseling as has been pointed out). But is was a lot less than normal.
I then eventually managed to get the nut slacked on the distributor slackened off (special 9.5 nut with rounded shoulders and a shallow screwdriver proof slot). I adjusted the timing back a couple of degrees according to my ebay timing light. She looks like she is at about 14 degrees at 900rpm. This is a few degrees less advanced than she was before. She sounds healthy and when I turned her off she stopped very nicely. There was the briefest of scuttle shakes and then peace and quiet.
I did this a few times and the same resulted each time.

I have suffered this symptom through a 3000 miles trip round the Alps and several thousand other miles so I don't think it was a real problem. But hopefully backing the timing off will ease the situation and put less stress on the engine and starting as a whole. But I will get her timed professionally soon.

Many thanks to all those who gave very useful advice. I have used forums before and especially in the Triumph bike world there are some very overbearing characters. I have not found here. The sort who WRITE IN CAPITALS as if they are shouting and the sort who criticise you for being naive or inexperienced. So thanks.

And finally may I recomend Robin Hood motor factors in Chelsfield in North Kent. Very old school and had my plugs in an hour and charged me £10 for the set. I will try the BR7ESs for a while and see how they cope before resorting back to the BR6ESs.

Sounds like you've found the solution - well done.

Is the quoted BR6/7 ES a typo?

A BR6ES is a resistive spark plug with a non-projecting nose. The correct non-restive plug for that engine is BP6ES, and if you must have resistive plugs (I have a grave disliking of them) then one fits BPR6ES which is the resistive version of the projecting nose.

I'd need to check with my books, but I can decode all the letters on older NGK plug types.

Typo!!! BP7ES.

Glad that you've found the solution. Happy Morgan motoring!