Running Rich

[oddbod]

OK I'm new to Moggies so please forgive my ignorance. After problems starting this morning,not unexpected given the weather,poor sparking was diagnosed, a new set of NGK plugs fitted ( no gap check as I dont have feeler guages at min) the car fired up, hurrah. On a run later this evening the car feels to be running rich, and not as well as when I drove home with the old plugs in. I am assuming that the timing,points and carb were all set up on the old,pretty duff plugs. Question is, where do I begin the process of re-setting the balance up so it runs nicely again. I have a haynes manual and can do a bit of spannering but I dont want to start messing with too much at once,any ideas where to begin? I thought moving in the mix screw on the carb?

[bmcecosse]

Check to see if the choke has perhaps stuck partly ON. What colour are the plugs ? Don't fiddle with anything until you have good reason to do so!

[oddbod]

Hi BMC thanks for the advice, its possible the choke is stuck,reading thru the manual this evening I saw that cleaning the air filter was a good idea too and I figured that(hopefully) doing that tomorrow wouldn't do any harm. The plugs I removed I intended to clean up,regap( when I buy a set of feelers) and have in a "spares" box. When I took them out they were 3 different makes and had varying degrees of what I can only describe as gunky/rust on a couple,so they are in the bin. As the car has had new points and a new condenser recently I can only assume it was set up to run on less than efficient plugs, I dont want to mess with anything,but the car is definately not running as well as Friday when I got it ,and the only thing I've done so far engine wise,apart from a fluid check is change the spark plugs (they are not gap checked either,but I cant see how that would make the car run rich) The old plugs were black and sooty and seemed damp with fuel. I have read with great interest your Pat Pending Spark Plug colour checker after driving hard up a long hill, and after describing the recommended procedure to my Mrs. she has agreed to accompany me on my mission to drive up one of the many hills in the surrounding Pennines and watch as I attempt to leap from the car as it rolls to a halt,plug spanner in hand and do battle with the bonnet catch!! I'm NOT planning to twiddle mixture screws,or adjust Carbs yet,though the dashpot oil is fine, I just want it to run well and not drink quite as much fuel!

[mike.perry]

Adjusting the carb is quite simple. Having got the engine up to running temp and checked that the choke is fully in, switch the engine off and wind the brass nut under the jet fully up and then down two turns or six flats, then mark one flat with tippex etc as a reference. Start the engine and turn the nut up or down a couple of flats until you have the smoothest idle. If you get lost you can always go back to the reference and start again. There is a special SU spanner for adjusting the mixture nut

[autolycus]

I'd get those new plugs gapped asap. I've just fitted a set of new NGK plugs to an old car, and they were around 40 thou out of the box (should be 25). With respect, your comments about setting up timing and mixture for the old plugs suggests that you're fairly new to this game, so I wouldn't rush to a diagnosis of incorrect mixture - get the basics right first. Assuming the new points were fitted and set correctly (rash, I know), make sure that the coil, distributor gap, and HT leads are clean and dry, even in the little spaces round where the leads connect to them. Carburettor settings and timing rarely change dramatically spontaneously, and rarely even make the difference between running very badly and running adequately.

When you've started it from cold, do you find you can push the choke in straight away without it making much difference, or does a moderate amount of choke help for a while?

Kevin

[oddbod]

Kevin, I am new to this game and am aware of my ignorance in all things Minor . I am getting great advice and support so far on this forum, so any help is gratefully received. I havn't messed with anything in the timing or mixture set up yet,but a mate, who has had old Petrol engines in the past,is up for coming and laughing at my ignorance,abusing me and drinking tea while he does so ( I'm not easily offended) but, in simple terms, explain how changing spark plugs could SEEM to have altered how the car runs.The only difference in driving conditions (since I bought the car on Fri 3rd Feb) is that I've done local,8miles or less,trips. The day I bought the car I did 150 miles on mainly Motorways and dual carriageways. I understand that I may be percieving a difference in driving where none exists,but as the Moggie started this morning @ 10ish on half choke (yep it continues to surprise me with its reliability) I'm not going to mess with anything until it becomes LESS reliable.It was just a general request to figure out where to start IF I am right and it is running rich

[autolycus]

in simple terms, explain how changing spark plugs could SEEM to have altered how the car runs.

If the plugs were of the correct type, properly gapped,and correctly fitted (simple stuff- tightened, plug leads back on the right plugs), I'd expect the car to run, if anything, better. So why might plugs with too wide gaps cause poorer running? As every plug is about to spark, the HT voltage, produced at the coil and transmitted through the king lead, distributor cap, plug lead, and plug cap to the plug, rises until insulation somewhere breaks down, at which point a spark occurs. The intention is that the first insulation to break down should be the air gap at the plug tip. The voltage needed for this to happen depends mainly (but not entirely) on the width of the gap and the pressure of the gas in the cylinder. Higher pressures occur when the throttle is wider open. If, while the voltage is rising, an easier path to earth arises, such as by tracking across a poor distributor cap, or breakdown of the insulation of a plug lead, that's where the spark will happen, not in the cylinder where it should be. The engine will then hesitate. If it's just one plug that's widely gapped, or one HT lead that's duff, you may get a regular misfire ("running on three cylinders"). Hence why a car that will pootle along at gentle throttle may hesitate and misfire when you hoof it.

the Moggie started this morning @ 10ish on half choke

Could you then push the choke right in almost immediately without making it run badly?

Note to some of the regulars: I do realise that there are many more factors influencing the breakdown voltage at a spark plug, but I am trying to focus on the ones that might have changed. Extra note to one regular: I've not blamed the coil itself this time.

Kevin

[MarkyB]

in simple terms, explain how changing spark plugs could SEEM to have altered how the car runs.

It's because you have done something and spent money on it.
You would need to put it on a rolling road before and after thus letting a machine tell you as we are all susceptible to the placebo effect.
It's the same effect that many producers of additives and add-on gadgets rely on.

[bmcecosse]

Sure you didn't mix up the plug leads when swapping the plugs....... Check they are connected 1342 anti-clockwise around the dizzy cap. #1 is at the front - so trace the lead for that plug back to the dizzy - then move round the cap anticlockwise to the next lead and trace it up to the plug - should be going to #3 - is it?? then the next lead should go to # 4 and finally the last lead to # 2.....

[mike.perry]

"The day I bought the car I did 150 miles on mainly Motorways and dual carriageways".
Brave man! If it let you drive it that far on its first trip, knowing that you were not mechanically inclined and probably without a tool box in the boot then you were extremely fortunate, as it is a well known fact that a newly aquired Minor will always try to break down at the most inconvenient time and place.

[oddbod]

Cheers Mike, you are quite right I am not mechanically minded , but I am up for a bit of an adventure and,although serious about running my Moggie as reliably and safely as possible, I aim to treat our car as a bit of a luxury. I cannot imagine (yet) myself having a Basil Fawlty moment about a breakdown,worse things happen and we do have a more modern reliable as a vehicle that needs to perform every day without fail.

[oddbod]

Sure you didn't mix up the plug leads when swapping the plugs....... Check they are connected 1342 anti-clockwise around the dizzy cap. #1 is at the front - so trace the lead for that plug back to the dizzy - then move round the cap anticlockwise to the next lead and trace it up to the plug - should be going to #3 - is it?? then the next lead should go to # 4 and finally the last lead to # 2.....

I'm sure I didn't mix up the leads, as I changed each plug before removing the next lead 'cos I am quite easily distracted.
Please don't think I'm complaining because as far as I can tell all the working bits (still working so far) are fine and dandy and am beginning to think I am fortunate to not yet have discovered any lurking horrors. It came back from the mechanic today with no faults other than those I knew about myself. He did only check the back end though and removed a "lowering kit"? Which involved longer U bolts and some spacers. He reckons a new/recon set of rear springs would be good soonish and I think I've just located a pair,but they are not on a car at present.Any idea how to check, by measuring end to end maybe,if they are off a Moggie or not they have got 5 leaves so I think thats a start!!

[bmcecosse]

These lowering kits are the daftest thing out.........most Minors have sagged down at the rear plenty without any additional 'lowering'....... Check how much clearance you have now between the bump stops and the chassis pad at the rear. Ideally you need ~ 2". You can cut an inch off the top of the bump stops if the clearance is a bit too short. If the bump stops have broken off (entirely possible if it's been running low) then get/fit new ones urgently! Did the mechanic sort out the running ??

[oddbod]

Hi BMC, the Moggie is still at the garage,so I didn't check bump stops,or chassis pads cos I dont know what to look for ,but I have my Haynes manual open on the kitchen table and will look when I get a brew in a minute. I AM happy that the Moggie is running and will get ( I hope) some feeler gauges tomorrow on the way to pick up our car, I then intend to warm it,pat it smile, adjust my lumbar support then drive it and my Mrs. briskly up a steep hill,turn off the ignition and coast to a halt and check the plug colour as recommended by your good self. I hope to then convince my self all is well,or not as the case may be. I went over to a local scrapyard today and found an almost identical 2 door to mine,even the same colour scheme,white outside red inside.It even seems to have a better boot lid and doors than mine!! So I maybe able to salvage some bits off that one.

[mike.perry]

Also check the drop link between the damper arm and chassis, the rubber swivel joint wears out. Also make sure that you fit 5 leaf springs, not 7 which are Traveller springs

[bmcecosse]

You need to do a good 10 miles of reasonably hard running - before attacking the hill. Grab all you can from the scrappy! But I doubt you really need springs if it was running with a 'lowering kit'....

[kennatt]

just to clarify bm advice don't just switch it off and coast to a stop.Put the clutch in and stop as normal then switch it off once you have stopped,it sounds as though you intended to just switch off and then let the car come to a halt.The idea being that you don't let the engine tick over before checking the colour of the plugs.If you let it come to a stop still in gear then this will cause the plugs to become wet with petrol so the test will be useless.An easy way to check the rear springs is to look at the rear spring hanger it should be pointing just to the rear of the car or straight up and down when new if it is way back and nearly touching the chassis leg then its time to replace,are you sure it was a lowering kit not a spring compensator which are available to assist weaked springs and commonly use for stiffening up the rear for towing.

[autolycus]

<SNIP> will get ( I hope) some feeler gauges tomorrow on the way to pick up our car, I then intend to warm it,pat it smile, adjust my lumbar support then drive it and my Mrs. briskly up a steep hill,turn off the ignition and coast to a halt and check the plug colour as recommended by your good self.

I'll say again: you won't get a proper diagnosis of whether or not your engine is running rich if it's misfiring due to other problems. You asked - I hope as a genuine question - why putting new plugs in could affect how it ran. Are you still unconvinced?

Kevin

[bmcecosse]

You DO want to switch off at speed -but also (I thought obviously) dip the clutch and slide into neutral at the same time......

[oddbod]

<SNIP> will get ( I hope) some feeler gauges tomorrow on the way to pick up our car, I then intend to warm it,pat it smile, adjust my lumbar support then drive it and my Mrs. briskly up a steep hill,turn off the ignition and coast to a halt and check the plug colour as recommended by your good self.

I'll say again: you won't get a proper diagnosis of whether or not your engine is running rich if it's misfiring due to other problems. You asked - I hope as a genuine question - why putting new plugs in could affect how it ran. Are you still unconvinced?
Yep I am asking genuine questions, and I dont THINK our Moggie is misfiring ( it seems to run happily to me) but I am almost totally a fish out of water, even really simple stuff I can C*&k up, but I'm not afraid to ask questions, dont feel you are patronising if you offer what seems (to yourself) basic instructions 'cos I really know nowt, I've got a Haynes Manual and some enthusiasm but not much cash, so how to fix stuff is important. Thanks for your input and patience I still think the engine may be running rich as it has started on half choke or less for the last couple of days, its not been above freezing here for 2 days,and runs quite happily with NO choke after 1min or so. Thats why I think its( probably )running rich. As to the change of spark plugs: if the mixture was set for the old plugs,hard black deposit and an "orange" weak spark,wouldn't the mix need to be stronger combat ignite a "weak spark".... or am I ignorant of combustion too?? ( I could be i think, I'm just guessing)