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MG Midget and Sprite Technical - LCB

midget 1275 HIF 44 Electronic ignition from Simon BBC

Following comments from a MASC friend I have fitted a LCB to the manifold. The fitting of the middle & back box was entrusted to a local garage who advertise as classic friendly. The garage collected on a loader but had to return on the loader with the Midget in a partly running state with the final few metres poping and back firing into my garage.

Their promise was to come and collect the following week & then tune.

Next morning I had a much larger pool of engine oil on the garage floor than I was used too. Could this be because of the garages handling?

Meanwhile I have had a few attempts to get the car going myself. The plugs were vey sooty so cleaned them up. I have checked the fuel pump & this is running well and the earthing is good.

I thought the sooty plugs could mean the carb is running to rich - could this explain the poping & back firing? Anyway I decided to lean it out a quarter of turn at a time & on the 3rd attempt got it running for a few seconds. Leaning it further by the 5th attempt the engine ran at fast idle for 5 mins until I tried to attempt a gear engagement but it became clear the the engine would stall & I could only maintain the engine with a couple of 2-3K blips after which the engine would soon stall again.

Each time I have got the engine running the plugs need a clean to ensure the engine will start again. I have so far been unable to reach normal running temps but even if running for a few minutes it is not possible to start the engine again unless it has stood still for 10-15 mins.

Any thoughts/suggestions are welcome.

Gavin
Gavin Rowles

Initial fitting of a manifold should not need messing with jet setting - that should be when it’s running fairly ok.

First do the choke levers still come fully off ?
May be stuck on ?

Manifold gasket leak would pop and bang but should not be rich - plug leads on correctly?

Some Classic friendly garage !!!

R.
richard b

Sorry on initial reading I thought the garage fitted the LCB as well.
Was it running OK with the LCB before you had the garage fit the exhaust - have they removed the carbs - maybe to alter the manifold to pipe fit etc ?

Still worth checking the chokes and plug leads.

Have to assume the boxes are clear ?
richard b

Start thinking logically

Was it running fine before the garage trip?
What - exactly - did the garage do to it?
Fitting of an LCB and the gubbins downstream of it should not particularly affect anything too much, but without understanding exactly what they did, it is difficult to comment.
If all they truly did was fit the centre pipe and back box, then what have you done to it since?
Very few things just happen for no reason.

Rich running could be due to

Totally blocked air inlet/filter
Choke mechanism/flap stuck
Mix well off
I recall on the HIF44 there is a balancer hole/orifice or something somewhere on the inlet flange. Critical that this is not blocked - by a gasket or something.
Float stuck
Float needle valve passing

No idea about the oil leak - could be anything.

Oggers


Yes, the popping and backfiring is likely due to the fouled plugs.

A couple of possibilities sprung to mind.

The first is fuel level creep in the carb due to a leaking float or the needle valve not sealing correctly. Causes can be too much pump pressure if aftermarket pump, worn valve, dirt on valve.
If you remove the dashpot you may be able to observe the fuel level and see if it is creeping .

The second is the plugs fouled to an extent that a simple clean won't fix. One of the things we have from time to time is plugs that foul while a car is at our workshop. There are two reasons: choke left on too long after start-up, and a succession of cold starts moving the car within/in&out of the workshop without ever getting to temperature. Most often, a combination of the two.
Sometimes when they get fouled in that way nothing short of a media blast or new plugs will bring it right.

The way you describe it running now indicates it may be too lean. If so, the mixture may have been right before being adjusted and then when it was leaned off it has become too lean to run properly.

Whatever the cause, the best way forward is to reset the carb jet to default (90 thou down from the bridge would do), fit a new set of plugs, start it, bring to temperature and the finalise the mixture.
Paul Walbran

ETA: I didn't see Paul's post before typing mine but my post still stands, and I'd certainly agree with buying new plugs for their low cost alone and more so if yours are more than 2 years old. NGK BP6ES, and I can remember nothing normally.

Gavin,
having been through something like this recently as Rich and Oggers have put go back to basics, if the garage only fitted the middle and back box it *should* have nothing to do with it (* depends on if anything else was done or happened at the garage, been there more than once *).

So that leaves whatever you done plus the usual items breaking or faulty for themselves and usually Sod's Law.

Engine - breather connected and clear, bling chrome oil filler cap instead of standard plastic, dipstick grommet fitted(?).

Sooty plugs could be from using choke and not driving the car far enough to blow the soot off.

Depending on type of popping and backfire could be ignition -
. igniter heads have delicate wires that can get trapped and abraded
. rotor arms can play up
. dissy caps can be iffy
. HT leads worn/faulty
. spark plugs, faulty, gapped wrong
. coil breaking down

air filter -
. full of debris (ahem! guess how I know)
. inlet blocked (by forgetting to remove protecting paper, can't imagine anyone doing that though ;)

Carb, well as mentioned before.

Engine controls, cables all free and fully functioning.

I'd advise you based on my recent experience to go back to checking all the basics and check tappets and timing forward.

You might have the carb too rich, or too lean, to run well off fast idle, try making it leaner or richer so the idle increases with the adjustment, and set idle to about 1,000revs and leave it there just to keep it running off fast idle to see what happens to the running, and to get the engine fully warmed.

I found my issues were a combination of things including me and my memory and not following my own advice of rechecking what I'd already double checked before.

Good luck, it's all "good fun" (not).
Nigel Atkins

Thanks all. I have plenty to look at.

I will update in due course.
Gavin Rowles

I deleted the word 'oil' by mistake, with below I was referring to your oil leak.

Engine oil leak - breather connected and clear, bling chrome oil filler cap fitted instead of standard plastic(?), dipstick grommet fitted(?).
Nigel Atkins

The oil leak may just be after off loading down ramps from the low loader. It may have been a steep enough angle to flood the rear scroll, or gearbox input/ output shafts depending on which way it was tipped. I am suggesting this as I understand you to say this is something new only since the garage had it.

I haven't followed all of this thread but understood you to say the car ran ok before the garage got involved - though possibly the other change before that was your replacement of the LCB manifold. So popping in the exhaust could be an air leak at the manifold. Check that first, especially on the underside if the joint to the head.

Other than that there's nothing that fitting a new exhaust could cause any problem with the running of the engine, unless they decided to start fiddling. But maybe there was a pre-existing fault.

If you can get it started and running, even roughly, then check what the rev counter needle is doing. An electrical fault (LT) will show up as a wildly flickering needle. If the needle is steady, or simply following the erratic running engine,then you can rule out any LT fault and it will be fuel or HT circuit - Plug leads in the right order?
GuyW

I had similar difficulties starting my 1500 after playing around with the installation of the inlet manifold and carbs and in particular the carb heatshield (which I had cut vertically in two to make installation easier!).
The upshot was that one half of the heatshield - the back half which is difficult to see - had moved before the second carb bolt had been inserted!!
It was just possible to get the engine to start but not to get it to run.
Did your garage by any chance disturb the installation of the inlet manifold or its connection to the carbs?
Tony Wood

Guy - noted on oil comment. I hope this is the issue. I will check on the rev counter too.

Tony - I have since return loosened off the manifold & refited. I can only check for leaks once it is running consistently which is an issue in itself. So whether the garage meddled with the installation or not I am unsure. Having fitted again myself I am fairly confident on this aspect.

Paul - I have fitted new plugs but to no avail.

Nigel - looked at your pointer but can't see anything wrong.

One thing I do plan to purchase is new Leeds/cap & red rotor.

Gavin.



Gavin Rowles

The rev counter is not jumping about wildly so not low tension circuit.

Gavin
Gavin Rowles

Gavin, I had a fairly recent thread going about setting up the carbs in my Frogeye. The problem I was having was to get it to run well enough to be able to begin to adjust them! It was popping and banging in the exhaust, had sooty plugs, wouldn't rev and wouldn't tick over on its own without me jiggling the choke and accelerator cables. Sound familiar?

The problem with mine was (at least) two fold. First the rear carb was flooding with the float needle sticking. And secondly although virtually all of the electrics were new, when I swapped in a different dizzy it cured it. The change of dizzy meant new CB points and condenser so it seems likely that was where the problem was.

This may all be irrelevant if your problem is really associated with the garage fitting of your new exhaust. But if along the way a fault has occurred for a different reason, like for example, picking up dirt when the fuel tank was tipped, and the carb jet isn't now closing properly, then that could be worth investigating.
GuyW

Gavin,
there are 'red rotors' and red rotors. The ones Accuspark and Powerspark (Simon BBC) sell look exactly the same as far as I can tell as I have both. They look fine but not as good as the Bocsh and Beru I normally use.

For the original Red Rotor Arm I'd suggest you buy from the originator The Distributor Doctor, I also suggest you get your dizzy cap from him too.

The Powerspark HT lead sets use ferroflex which is good and at a good price, I think Gary was pleased with his set but they are 8mm so a squeeze to get ito the cap.

Unless Accuspark have improved their HT leads I wouldn't buy them.

Original Red Rotor Arms - http://www.distributordoctor.com/red-rotor-arms.html

Dissy cap -
http://www.distributordoctor.com/distributor_caps.htm

SimonBBC HT lead Set - https://simonbbc.com/MG-Midget-MK3-MK4-4-Cylinder-HT-Leads-8mm-Double-Silicone
Nigel Atkins

Gavin,
just thought, perhaps some general engine bay photos might help to highlight anything unusual or non-standard (other than HIF44, igniter head and LCB I mean).
Nigel Atkins

Guy & Nigel thanks for your comments.

I spoke to a tech person at Burlen yesterday & set the feeling at the recommended level below the bridge. He was confident that it would run OK - if fueling was the issue. However no change.

I have a couple of spare coils & caps/red rotors & will give these a try to see if I get any improvement. If so, I will buy new parts from Sussex Spares.

I will check the float if my ignition adjustments fail.

Gavin.

Photo's I will try & to sort later.
Gavin Rowles

Gavin, did you check on the tachometer needle?
The other thing is to listen for your fuel pump ticks as that could indicate if the carb is flooding.
GuyW

Guy,
you missed Gavin's reply -"The rev counter is not jumping about wildly so not low tension circuit."
Nigel Atkins

Gavin,
I'm not sure Sussex sells Dissy Doc Red Rotor Arms I'm guessing they might be Moss or Accuspark/Powerspark, those three all might be the same, I've never seen one from Moss so I don't know.

If you know the spare coils, caps and red rotors are all good then swap them out one at a time to see what works.

If you want to buy more new stock of these then having myself pissed (not the word I really wanted to use) with getting the car running I would go for Dissy Doc stuff if I was you be sure of the quality, fit and forget.

Personally I found SU Burlen to be about as useful as a fart in a corlander.
Nigel Atkins

Sounds like fuelling to me rather than ignition/timing. Floats stuck/Float needle valves sticking/mix well off/choke stuck closed..are all these good?
Oggers

OK folks - good news.

I tried a good second hand cap - no change.

I tried a 2nd hand coil and bingo!

Thanks for all the idea's & suggestions.

I will purchase all new items as required .

I can't help feeling the coil was degraded by the garage.

I won't be using them again!

Gavin.



Gavin Rowles

I wonder if the ignition was left on and the coil broke down due to overheating, that could explain your cure?
Colin
C Martin

Good news Gavin.
Well done in locating that!
GuyW

Yes well done on finding the cause.

I'm not sure I'd blame the garage, would a coil overheat by leaving it just switched on, and how long would it take?

I gave away a coil years ago because I'd left the ignition on for a day, there were no signs that I needed to replace it but with my luck and the low cost I did, and the same coil was lent back to me recently to test mine was OK. Both coils were fine.

New 'Lucas' coils are Elta, they make them "ELTA are a proud licensee of the iconic Lucas Electrical brand . . .".

I recently bought an Elta VXPRO EE5001, the Lucas sports coil with different badging (it's slightly narrower than my previous 'Lucas' DLB105). The bracket and terminals had a definite India/China look and feel about them but the coil seems to work well. £17.99 on eBay.

Looks like Elta have gone back to (a different style of) red boxes for their 'Classic Electrics'.

https://www.eltaeurope.com/classic-car-electrical-parts/
Nigel Atkins

IF, it was the wrong coil on the car then yes it would normally overheat and die from being left turned on but you have electronic ignition so there wouldn't be any draw through the coil anyway, I doubt that to be the issue
IF, the ignition was left on and they did some mig welding on the new exhaust then maybe that could have killed the coil but I'd more be inclined to think the electronic ignition or alternator would have died first

I'm thinking it's not been the garage's fault, just bad luck/timing

Did they do a good job on the exhaust--that's the main reason to decide if you use them again
William Revit

You sure it wasn't he HT lead or any other connection rather than the coil itself? Coils are usually extremely robust.
Oggers

I think with electronic ignition the coil will still draw current if the ignition is switched on. The electronics switch off the current at the appropriate time just as points do.
If you leave your ignition on you'll be surprised how hot the coil gets.
The coil is filled with an insulating liquid to aid cooling (or more likely to prevent hotspots). The liquid is put in through the HT connector and then sealed. Modern coils are sealed using a self tapper screwed into plastic through an O seal. The mounting arrangement for the coil in most Midgets and Sprites has the coil mounted with the HT lead at the lowest point. You see where this is going? If the seal isn't particularly good the liquid will leak out very slowly and the coil will get hotter and hotter over time just waiting for the time when you leave the ignition on.
Modern coils are not well made for a number of reasons (the sealing arrangement being the worst) and I much prefer to use original where possible.
If you shake a coil you should be able to hear the liquid inside. If you can't it is empty and will be prone to overheating.
I'm not sure what the liquid is but I think it may be Liquid Paraffin (which is NOT normal Paraffin).
Rob
MG Moneypit

Rob, to the best of my knowledge the liquid is just transformer oil.
It sticks in my mind that transformer oil is basically coconut oil, but I don't know what additives it has.
Anyway its fairly cheap in small quantities. I had some until a couple of years ago for top ups for my Oxford welder, which I no longer have since someone decided he deserved it more than me.
The brand was Diala B.
Greybeard

If it was the coil LT wire that had broken down, then the rev counter would have been flickering, but I think you checked and it wasn't. Suggests that if the coil was at fault it was to do with the HT side, or connection to HT lead as Oggers says.

Incidentally, I had a coil overheat when I left the ignition on. It blew the end cap off and all the oil drained out. As a " get home" from Scotland I pushed it's entrails back into the can and it still worked. I did over 2000 miles before I eventually fitted a replacement. They are pretty tough devices, but often seem to get blamed for ignition faults.
GuyW

Carry a spare coil fitted somewhere in the engine compartment.
Alan
Alan Anstead

This thread was discussed between 10/10/2020 and 16/10/2020

MG Midget and Sprite Technical index

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