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MG Midget and Sprite Technical - Sooty Plugs

HI all,

I have been working from the premise that sooty plugs (all of them) is a carburetter related problem as the diagnosis chart for plugs gives this as one of the main reasons (I have checked the rest on the plug diagnosis list).
Are there any other ways that (all) the plugs could be sooty rather than the carburetters?

Dave Squire - Notts

What grade plugs are you using?
Do you get the engine up to proper running temperature before doing a cut?
Is your choke mechanism free to return fully once warmed up.?
Guy W

I believe that it is a carb problem and sounds like the car is running too rich however I also think that if the car is only started once in a while on choke and not run properly this could give the same indication but the carbs might be fine.?
C Carter

Hi,

I posted this on the misfiring post which maybe useful:

Soft, black, sooty deposits easily identify this plug condition. This is most often caused by an over-rich, air/fuel mixture.
Check for a sticking choke, clogged air cleaner, or a carburetor problem - float level high, defective needle or seat, etc.
This may also be attributed to weak ignition voltage, an inoperative preheating system (carburetor intake air), or extremely low cylinder compression.

Good luck

James
J Paul

Dave,

A good point in James list - air filter - is it fairly clean ? have seen some pretty choked examples where not changed at service intervals.

R.
richard boobier

Hi Richard,

Are you around this weekend. I would welcome some advice on the next steps for my restoration?

Kind regards

James
J Paul

Dave,
I might be wrong but do I get the impression you put getting an MoT in front of servicing the car(?) (sump nut seized suggested oil hadn't been changed) IF that's the case then dirty air filters plus loads of other bit might not be helping with your sooty plugs

also remember short journeys and/or use of choke could soot plugs, if the plugs are the correct type and you've not already cleaned them then put the back in sooty and go for a good blow out run and look at them again

as you've recommissioned the car, as with a car new to you, I'd suggest doing a 36k-mile service/check and then frequent use

Nigel Atkins

You are absolutely right Nigel.

And now I have sorted the filters out it runs fine.

Beats fixing the carbs anyday however now that I know how the carbs work I do feel accomplished. I always found it a mystery when I was young and red headed and after a lifetime of mental adjustment I have won through and the pennies have dropped. All due may I add to all of you bearing with my strop and kind offers of help in the week.

This will teach me to ask the correct questions in the beginning! - 'keep calm and carry on' I think they used to say - This question should have been: - What did I put back on the car after it was running correctly to cause it to not work correctly just before I took it for its MoT? Answer: - The air filters.

So its for a drive 2 morrow when I have fixed the ..... brakes!
The banjo leek I asked about a few weeks ago was actually a brake union leek. Found that out today when taking car out of workshop. Got good handbrake! However have all the bits and the kit to fix that one so looking forward to a drive at some time this weekend. Then I can get on with improvements.

Thanks again everyone. Cheers, Dave
Dave Squire - Notts

"Sooty Plugs"

Really? Some people used to say Sooty sucks too, but when I was a kid, I quite liked him.

"Bye bye everybody! Bye bye!"







Lawrence Slater

James,

Yes I'm around this weekend give me a ring to arrange.
872585.

Lawrence,

I used to think he was great !
Seen repeats recently and its hard to believe what impressed me then !

R.
richard boobier

Dave,
you've got the order right now, fix brakes then drive

have a look at the servicing schedule in the Driver's Handbook and go through a 36k-mile service/check and that will sort, find and prevent problems

this is a good illustration that a car can have a fresh MoT but still not be in its best condition or drive well

these old engines do like clean air filters and thorough oil (and filter) changes

but the engine and carbs are not very important - brakes, tyres, suspension, lights and windows are much more important

in case you've not seen I've got non-technical, non-mechanical, general notes and advice which most find boring but a few have found useful (or too polite to say otherwise) if you want any email me
Nigel Atkins

Dave,
Glad to hear that your carbs are sorted, now get those brakes sorted and give it a good run. You'll find she run better and better the more miles you drive.
Pete Ottewell

I just can't wait Pete. Missus back at work 2 morrow on an early so I will be up at about 5.00 am. Lists done, workshop organised ..... onward.

Speak on the morrow.
Dave Squire - Notts

Lawrence,
I think you'll find it was Sweep or Sue that sucked
Nigel Atkins

Heh heh. What on Nigel? Sooty's wand by any chance?
Lawrence Slater

This thread was discussed between 04/01/2013 and 05/01/2013

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.