24 replies to this topic

[skoughi]

Currently running in my 1330 just now, 266 cam shaft, aldon yellow spec distributor with electronic points, Hif 44 with K&N cone filter. Compression ratio should be 9.8-1 and the timing was set a 9 deg, bp6es plugs and the AFR gauge is showing readings that are good but for a slightly rich idle, she drives good with no hesitation when accelerating. The problem is that she'll run on when the ignition is switched off but not always, sometimes she'll stop dead the next she'll make two maybe even three revolutions! Any things I can try to help stop this?

[cal844]

What I do when stopping the engine(as advised on here)

 

Stop the car with brakes

Clutch to the floor

Put car into first or third gear

Right foot hard on the brake pedal(handbrake on too)

Kill power to engine  and lift clutch pedal 

Keep brake pedal pressed until engine stops!

[skoughi]

Hahaha! Yeah I've seen that solution come up a few times on searches on this topic! What's the reason for it happening though? There must be a few things that can be adjusted/changed to help stop it?

[Swift_General]

Run on is caused by the fuel igniting when the ignition is turned off. Can be too high a compression ratio or a hot spot in the combustion chamber (does it need a de coke?). You could try cooler plugs (BP7ES), although I would have thought the ones you have would be about the right heat range. If you're happy there are no issues with the engine (a series do have a habit of running on) then fit an anti run on valve as run on will can ultimately lead to engine damage.

Edited by Swift_General, 14 June 2016 - 11:47 PM.

[skoughi]

My compression ratio could indeed be the problem as it may be on the high side. I have a bk450 which would give me the chance to take the head back off and check the chambers as well, but that'll be a last resort! I've read about trying no7 plugs as well, I'll maybe look into the anti run on valve and see if I can get one. I think for now I'll have to stop her in gear with the clutch biting to stop it happening, it's not a consistent thing though so I would've thought if the had had a hot spot then it would happen everytime, and the same with the compression ratio?

[skoughi]

Run on is caused by the fuel igniting when the ignition is turned off. Can be too high a compression ratio or a hot spot in the combustion chamber (does it need a de coke?). You could try cooler plugs (BP7ES), although I would have thought the ones you have would be about the right heat range. If you're happy there are no issues with the engine (a series do have a habit of running on) then fit an anti run on valve as run on will can ultimately lead to engine damage.

I'm running it in after a rebuild so there should be no carbon build up, also every one says they have a habit of running on!

[MacGyver]

I had the same problem with my 1293cc engine on my first mini. Went to bp9es plugs but never cured it completely. I even went and put a standard head back on and still did it.
It got better in time and I got used to it until one day I put some high octane petrol in, and voilà! Cured it.
Sounds daft, but it did...

I think a combination of rich fueling from carb, wrong plugs and low octane fuel where not helping the high compression, so maybe you could try the bp7es plugs and high octane(100+) and see what happens. If it don't work you will only loose 5min of work and some more expensive fuel.

Ps: rich running is not too good for new engines... 😐

Edited by MacGyver, 15 June 2016 - 08:15 AM.

[skoughi]

I've been toying with the mixture, she was rather lean to the point that you could feel her slightly hesitent so I made her run slightly more rich, the AFR gauge was showing good readings when being driven, but she does have a slightly rich idle which may be making this worse. I might have another go at filing a little off the mid part of the needle so I can back off the mixture screw to lean out the idle a bit. After that I could try the no7 plugs. Up here in the Shetland Isles we only have 95 at the pumps so will just have to make do! I'm hoping to get a few more hundred miles on her and then pop down to the mainland on the ferry and get her set up properly on a rolling road, by someone who actually knows what they're doing! I'm going to look into an anti run on valve though, see if I can get one that the Metro's would have had fitted.

[skoughi]

Had a quick read on a Metro forum and they seem to advise a slightly rich idle mixture and colder plugs. Failing that stop it in gear with a biting clutch, but want to try and avoid that if I can!

[imaparana]

Try turning your lights on and elevatrics that will normally lower the idle then switch it off, works for me :)

[Pigeonto]

I never risk mine running on and always slow/brake the engine when switching off. If it kicks backwards which they can do there's a risk of chain tensioner breakage. Trouble is it's such a habit now, I do it with my diesel pickup truck too !! lol.

Don't listen to any one telling you the ignition is too advanced because there's no ignition when the key is turned to off !!

One thing not mentioned amongst the comments above is idle speed....the slower you can get it, the less likely running on occurs

Engine temperature is another factor, it mustn't be higher than normal, lower the better

EDIT, Imaparana has mentioned idle speed whilst I typed

Edited by Pigeonto, 15 June 2016 - 11:22 AM.

[absx2]

A anti run on valve was factory fitted to MG Metros and pre injection Rover Coopers so that was considered a satisfactory fix for a production engine that they obviously couldn`t stop running on so maybe fit one to your car.

They are fitted to many production vehicles so no big deal. 

[skoughi]

I never risk mine running on and always slow/brake the engine when switching off. If it kicks backwards which they can do there's a risk of chain tensioner breakage. Trouble is it's such a habit now, I do it with my diesel pickup truck too !! lol.

Don't listen to any one telling you the ignition is too advanced because there's no ignition when the key is turned to off !!

One thing not mentioned amongst the comments above is idle speed....the slower you can get it, the less likely running on occurs

Engine temperature is another factor, it mustn't be higher than normal, lower the better

EDIT, Imaparana has mentioned idle speed whilst I typed

 

I'll tweek the idle down a bit, yesterday I did think it was running a bit fast. Also according to the gauge then she is never higher than mid way, I fitted a front mounted Metro radiator and it seems to be very good at keeping her cool and that's with an 88 deg stat.

A anti run on valve was factory fitted to MG Metros and pre injection Rover Coopers so that was considered a satisfactory fix for a production engine that they obviously couldn`t stop running on so maybe fit one to your car.

They are fitted to many production vehicles so no big deal. 

I did an ebay search for one and as you say lots of different types from different manufacturers turned up so it's a popular quick fix. I'll try a few things and then maybe look into fitting one.

[ACDodd]

Get the idle speed to between 925 and 950rpm it should stop.

Ac

[skoughi]

Tweeked it down a bit and is a bit better, have resorted to stopping her on a biting clutch as well!