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MG Midget and Sprite Technical - Mallorca Midget

I'm back!
I gave up trying to fix my misfire and eventually took the car to a garage in Palma to fix it.
They have had the car since December and have just contacted me to say that they are stuck!
aaarrgh
ok recap:
I had a misfire that started after driving the car for 10 mins.
I had the coil checked and the garage said it was dying so I replaced that.... no cure.
Changed plugs, leads, cap rotor arm etc: no change.
Stripped the Weber & fould one float snapped off.
rebuilt Weber with new float assembly etc.
The misfire was worse, much worse. (dammed hard adjusting the float)
Gave up & took to garage.
So, they cant cure it. At least it wasnt me being thick.
Any more ideas guys?
Spec if you dont know it:

1430 stage II
Oselli Pistons
Weber 45
Lumenition optronic ignition (they bypassed it to test)
Facet pump
Speedking regulator
Frontline 5 speed box
etc etc....





Mallorcaben

I know it sounds daft, but do you have a pair of SUs you can put on the car just as a test amd find out if it will at least run (even though with less apparent grunt)

would give you something to work with

You did say there were problems with the Weber, so it could be worth a try
bill sdgpm

Do you know anyone at Iberia handling in LEPA? I fly for Thomson and might be able to get a pile of parts sent down by our engineers for you to try changing. I managed to get a conrod over to (IIRC) Arnold for his car via the same method.
What are the plugs? Copper or carbon leads?


Ummmm...want me to come over for a day or two?
rob multi-sheds thomas

Is the misfire constant? Consistent? Under what conditions? If you can force the conditions, keep it at the misfire for a few minutes, then immediately cut the ignition and check the plugs, it might be informative.

I also agree that a "known good" pair of SUs would be a good idea, if possible.
David "or not..." Lieb
David Lieb

Try Bills suggestion of substituting SU's if the problem persists then try a decent rotor arm. Current rotor arms are made of a more conductive 'plastic' than of old and the rivet that holds the brass contact on is longer so that they short out to the dizzy spindle. You can get a decent one from the likes of Distributor Doctor or Aldon Automotive.
Alan.
Alan Anstead

I fly the 767 (Beach fleet, or longhaul) out of Cardiff but at the moment the only Palma flights are on the 737 (Fischer Price fleet, or "Untouchable") so getting to PMI would mean jumping onto one of the 737s. I might be able to get 24 or 48 hours in Palma as some sort of 'training liason' thing and carry a bag of carbs and dissies over. Might that be a help?
I'll have a word tomorrow with the company just to see what they could do, otherwise I'd get charged for carrying the spares through security/immigration.
rob multi-sheds thomas

rob

can you collect a bag from my cousin in Columbia?
d cusworth

You have a cousin in Columbia too?
Mine has a bag to pickup too!
Put he said it can be carried in small plastic mini bags inside your belly so you dont have to carry the bag al the time.
You see, he is very thoughtfull and only has your best intrest at mind.
Just dont fart near any German Sheppard... LOL!!
Arie de Best

Damn it Ben -- i'm over there in M/y and was gonna ask nif you want to rent it out for a week -- if you need any small parts bringing then, let me know.
Mick - trying to sort the wiring

Arie,

I guess your cosin was able to find a way to also ship that large plactic bag ...the one that stood 6 foot tall and wieghed around 250 ponds...LOL

Beinng that you have checked the obvious
After the carb substiuite id look at the dissy shaft for play, and play in the crankshaft ... even the crankshaft pully if the rubber has gon bad

To add to davids qustions...was there a blue electrical light show under the hood in the dark of night...I to would love to know the answers david is asking

with the ilumination ignition....those things tend to hate vibration on the optic wheel...perhaps it needs buffers, ... Is the engine locked down tight, can it be sending vibration thur other systems, along with a SU carb subtituit, Id try a stock dissy in good working shape
Prop

Can you stop off at Alicante and drop off a hardtop for me . Thought about telling them its a sledge and bringing it out as sporting goods.
R Mcknight

how about the fuel pump, maybe its not keeping up with your weber.
ajs alan smith

check the flexible wire that connects your distributor base plate
Shawn

Is your weber mounted so that it is isolated from vibrations? You know, with the special springy rings?
Alex G Matla

I know nothing of Webers and wouldn't recognise one if it jumped up and bit me.

But, if the misfire that you had at first got significantly worse when you dismantled to fix the broken float, logic would suggest that there is something about the way the Weber is assembled that is wrong.
Maybe dismantling to replace the float loosened up some more crud and a passageway somewhere is partly blocked. A blocked jet would be easy to check, but internal passageway blockage not so obvious to spot. Bill's idea of swapping in another set of carbs would at least help narrow down the problem.
Guy Weller

Also chech the pressure after the regulator. If with one float it didn't close up the valve maybe with two it does and now there's no fuel enough.
Alex G Matla

rob multi-sheds thomas, South Glamorgan, United Kingdom
can you let me know your email address, this sounds VERY useful
UPDATE:
Just spoken to the garage, he is 99.9% sure it's electrics. He tried the Weber on another car and it was fine.
He doesn't have another distributor to test so he's a bit stuck.
I just need a working 2d hand one to test.
Anyway, the mechanic said it's driving him mad (tell me about it!)
It ticks over fine for 5 mins but as soon as he goes to move it, it misfires. Then clears, runs ok for a while but misfire comes back.
He said he suspects the distributor or the internal distributor drive..
--
Before I get acused of ignoring posts/suggestions again,
* Fuel pump fine
* Fuel flow fine
* plugs, leads, coil fine

Prop, yeah dissy shaft probably got movement in as it was an old dissy from a scrapyard I put in about 8 years ago.
Thing is though, optronic ignition cures all but a really bent spindle.
The garage have put the points back and this could be a factor, but the misfire is the same as it was when I was testing it with the electronic ignition in place.
Whats the deal with the crankshaft pully, I've never messed with this? What wears, how do I check etc etc.

If I find out 100% that it's the distributor, I am going to order an Aldon automotive one with the electronic ignition built in. Hate the optronic to be honest.




Mallorcaben

Ben,
I can hear your frustration! - and people like me telling you to look at stuff that you have checked thoroughly won't help! Sorry! The only reason I suggested a Weber fault was that you said the problem got much worse when you dismantled it to replace the float. Seemed to suggest a logical connection - but then who ever said that logic comes into it!
Guy Weller

Is it worth getting one of those cheap distributors to try it - rather than a secondhand one which will probably have the same problem!?!?!?! Or just accept the inevitable that it probably is - and get the one Aldon one! I would happily send you my old one - but - since it had the same problem, there's not much point ...!!!!

What about slight crystalisation between the different pipes?
rachmacb

Oh yes - it occurred to me that one of the problems deep down in mine was a slight mischord on the tuning of the engine which meant that one cylinder is fractionally out - it took a load of other things to be done first to discover it, but, even after that, she would still misfire every so often. Took me and several mechanics a few months to work that one out!
rachmacb

As an outside chance you could have your garage man check the voltage across the battery terminals with the engine off. It should read somewhere between 12 - 12.8 volts. Then start the car and measure again above 1500 rpm. It should read no more than 14.5 volts. Above this figure and the alternator is overcharging - apart from cooking the battery, you will get a misfire as the coil heats up and breaks down. It would recover when cool only to repeat the cycle when the volts rise and the coil breaks down again.
F Pollock

Ben,
Could very easily be an HT problem. A bad sparkplug wire or even a bad connection from the sparkplug wire to the cap or a bad terminal inside the cap can all do this. It will idle fine, but as soon as there is a load it will misfire.
David "let me tell you about the leads on my old Escort..." Lieb
David Lieb

If the missfire got worse after playing with the carb, that surely must be the issue, even if it worked OK on another car. Can you find something else from the garage to borrow (the carb he took off the other car to test yours with?)to confirm/eliminate the carb?
John Collinson

I've fitted a 123 distributor and am a big fan of these now.

Chard
R Fowler

Is that a ballast resistor on your pedal box? if it's in use, remove everything that is not part of the o.e. such as electronic ignition etc. another thought is valve clearances?
d cusworth

R Fowler, tell me more about the 123 distributor.
Any comparisons to the Aldon Automotive version (100AYS)
What are you feelings people?

D. Cusworth, they have bypassed my lumenition.
David Lieb, I've changed all leads, cap etc.
John (TSR?) The car was missing and after playing with the electricals I tackled the Weber, changing float assembly. They are a bugger to get right & I obviosly didnt because it was much worse after reassembly.
The garage appear to have fixed this as the car is back to the original misfire, ie after about 5 to 10 mins running.




Mallorcaben

see:

http://www.123ignition.nl/
and yes it is Dutch
Here you see the advance curves:

http://www.tdcperformance.ca/

you get 16! different advance curves with it, a variable dwell angle, positive or negative earth and a scatter stabilisation. What else do you want?

I own one, with standard Bosch rotor and cap, German stuff,perfect!

Flip
Flip Brühl 948 frog 59

Just try a better rotor arm.
Alan Anstead

Ben, like the frontwing arches on your midget!
Very subttle.
What are they, rear-arches(RWA), self made?
Arie de Best

Well it probably isn't the fuel injectors like it was a couple weeks ago in my VW GTi VR6 ;-) I actually took it to the shop to be fixed on this one. Between the 4.6 hours of book time just to get at the injectors in that car, the number of items that should be replaced any time they are touched and the blessed cold, it was almost worth it.
David "my next car will not be a VW" Lieb
David Lieb

if it indeed turns out to be the ignition go for the 123

they are great and make a hot engine pull like a mad dog and idle as sweet as a furry rabit

other than a distributor less system this is the way to go.
Onno Könemann

One other thing to consider (you probably already have too many).
I have in the past has situations where the inlet manifold had a small crack which opened up when the engine warmed, leading to a nasty misfire. The reason I mention it in this case is that the misfire got worse when you fiddled with the weber.
On my Elan I have also had issues in the past with the isolating O rings between the weber and the manifold. Check they are seated and arn't old and hard.
What type are you using? the ones with two separate rings per choke or the ones that come as a complete unit for 2 chokes?
Cheers
Tim
T Dafforn

I once had a very small hole in a core plug which would spray a very fine jet of water on to the dizzy when the engine was up to temperature! Just a thought!

Carl
C Bintcliffe

OK, tempted by the 123 distributor.
What is the model I would need?
CAR SPEC:
1430 stage II
1/2 race cam
Oselli Pistons
Weber 45
Frontline 5 speed box
etc etc....

I use the car everyday (when she's running!)sometimes motorway & occasional track days.

Advice on dissy model, proce etc.
Thanks

answers to Q's
* Don't really know who originally made the arches (it used to have race tyres)
They are mostly filler now. WIsh I had them replaced when the car was rebuilt 5 years ago with standard wings.

* I replaced the rotor arm (along with dissy cap, leads etc)

* Inlet manifold has been repaired at some point with liquid metal, I will ask the garage if they can pressure check it.





Mallorcaben

I see that you have changed the rotor arm but is it for another from the same source. The problem that has afflicted several owners, known to me, in recent months has been modern rotor arms. What is needed is a quality item available from Distributor Doctor or Aldon Automotive. Alternatively try one from a car that is running correctly.
Alan Anstead

Ben

the 123 comes in 1 model (to fit the midget) witch has all the advance curves buit in selectable through a verry small switch (hidden at a nasty place)

take the model without vac advance with your spec of engine and because the vac advance is purely electrical and not mechanical.

time it with a strobe
they have a bult in timing led but those are not that acurate.

the 123 has verry reliable beru/bosch rotors and cap's so you'll never have to worry about that again.
Onno Könemann

I reckon we ought to get a big team together and all fly out to Ben, fix his misfire. Then all carry on to Prop and get his engine started.

Should be time for a few drinks en route....

Roly
Roly Alcock

Have a look also at the mini 123 ignition and the curves.
And why not take a model with vacuum advance; you can disconnect it if you want.

Flip



Flip Brühl 948 frog 59

Yeah Roly, come on out here & bring a suitcase of spares. lol
No word from the garage, I keep emailing them your suggestions guys.
Just trying to get a dissy to test now. Anyone fancy sending me one, I will pay postage etc.
cheers



Mallorcaben

Just got back last night.
Ben. My E-mail is posted above.
rob multi-sheds thomas

This thread was discussed between 03/02/2010 and 14/02/2010

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