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MG TD TF 1500 - carburetors mysteriously rebels

Hello. I rebuilded the engine of my MG TD 1952. The compression go to 9,7-10 according piston. But I have a problem: The carburetters give a lot of combustible and the engine stop when it is running in road more or less 60'. No oil in the spark plugs.

I followed the instructions of the handbook for regulate the injectors and air inlet, the carburetters are completely rebuilded: new injectors, new gaskets, pistons rebuilded, new needles 0,90, lowered the level of the floats. The fuel pump is the new electronic S.U. but the problem is the same with other pump.

The injectors are regulate to 1/2 turn of nut for end of cut combustible. I think that the normal position is 6 nut turn of cut. The engine running with the injectors totally closed!!!. Is impossible regular the inlet combustible in this conditions.

I appreciate any help for solved this problem. I think that some solutions can be:

Brake the pistons of carburetters with oil more dense.
To put a spring in the pistons as late models carburetters.
Needle size 1.

Thanks for your help.
Jordi Mas

Hi Jordi;

I'm sorry, your English is much much better than my Spanish, but I don't understand a couple of the terms you use.

Does "combustible" = "fuel" or "gasoline/petrol"?

Does "injectors" = "jets"?

If so, it sounds like you are saying that the motor is getting too much fuel, correct? Even with the adjustment nuts turned almost all the way up?

If that is the case, your needles may be set too far into the piston and allowing too much fuel. Check to see that the "shoulder" of the needle is flush with the bottom of the piston and that it does not move. Don't forget to "center" the needle so the pistons move up and down freely with the needle in place.

Also, check to see if your pistons are moving up and down as they should. You should be able to move them easily with your finger without binding.

I don't think the solutions you plan to try will help. Those solutions are good for tuning a working carb, but your problem appears to be more fundamental than that.

Hope that helps. Please post back with any additional information you can provide.
David Littlefield

Jordi,

A couple of more ideas to add to David Littlefield's excellent suggestions:

Sometimes the wrong jets are provided. They should have an orifice of .090 inch. If they are .100 inch they are meant for a different carburetor.

You say you lowered the float level, did you remove the piston and chamber and look down from the top and see how low the fuel level was in the bridge of the carburetor (the raised section of the inlet where the jet and needle penetrate)? It should be .120 to .200 below the bridge level.

Also, please confirm that "6 nut turn of cut" is indeed 360 degrees of rotation (one full turn), or six nut flats down.

warmly,
Dave
Dave Braun

If you have the original oil bath air cleaner, try running it without the air cleaner. The top part can get squashed and restrict the air flow, causing a rich condition.
George Butz

air filter
Jordi Mas

Jordi, I assume that you replaced the jet seals. If so, did you you use genuine SU oil-impregnated cork seals? Some of the aftermarket kits, contained short pieces of rubber tubing that did not work well. If the seals are bad, fuel will get sucked right past the jets.
Steven Tobias

Hello Steven. I bought the jet seals with the kit for rebuild the jets at MossMotors and i followed the instructions of Moss for oil-impregnate cork seal (a day in oil). However, i will review again. I think Moss did not recommend S.U. oil in the instructions. Is this very important?. Any help is very useful. Thank you, Steven.
Jordi Mas

Jordi,

Steven meant Oil Impregnated cork seals made by SU. It appears that you installed the cork seals correctly.

What is the full designation of the needles you have? The typical needle is ES, slightly lean is AP.

Dave
Dave Braun

Jordi,

You say: "Brake the pistons of carburetters with oil more dense". Thicker damper oil will have the effect of making the mixture richer on acceleration, so that won't solve your problem.

If you have the proper ES or AP needles, fitted at the recommended height, please concentrate on the jets.
I had the same problem on my single carburettor YA and after a long search, I discovered that the new jet was .100 instead of the .090 it should have been (as Dave Braun rightly suggests).
It is also important to centre the jets properly.
I've fitted Teflon rings as jet seals with good results.
Also check that after using the choke, that the jet is fully pushed back up by the return spring.
Willem vd Veer

Hello. I checked today the solutions proposed. The needle has 0,87 inch. model ES, and not move in the jets. I bought the needles and the jets in the same kit. The "shoulder" of the needle is flush with the bottom of the piston. The pistons are moving up and down as they should.
I've seen the jets with the fuel pump activated and the fuel out only for the centre of jets.
The jet is fully pushed back up by the return spring.
I'm not sure the jets measure .90 but I think if the needles not move in, should be .90.

Please, what is the problem?

Thank you.
Jordi Mas

"I've seen the jets with the fuel pump activated and the fuel out only for the centre of jets."

Does this mean you can see fuel in the jets when you look down at the jet? Or is the Jet overflowing with fuel.

The fuel should be lower than the Jet.
By about 1/8 of an inch. (3-4mm)

If it is overflowing the jet, then bend the arms of the float lever down (under the float bowl lid) and try again.

warmly,
dave
Dave Braun


Hello Dave.

If the fuel pum is activated, the fuel out up to 20 cm. high. If the fuel pump isnīt activated is impossible to see the fuel in the jets. I will try to measure the high of fuel in the jets.

I think that the problem can be a excessive elevation of carburettors piston for a high compression produced in the cylinders. What do you think about this, Dave?

I follow appreciating any help. Thanks.

Jordi Mas

It looks as if we can't fault the carburettors? Can you post a picture of the carburettors on the engine?

What is the colour of the sparkplugs; are they black (indicating a rich mixture) or are they a lighter colour?

Did you check the timing of the ignition? Start with 0-degrees pre-ignition, so the spark should be at TDC (top dead centre)

Did the engine run good after the rebuild? If not you may want to recheck the camshaft timing.
Willem vd Veer

Ok. Thanks Willem vd Veer. I want discover the malfunctioning of carburettors. I donīt know if the problem is in camshaft timing or timing of the ignition. Two mechanics have been the carburetters. All suposed that TDC and camshaft are correct. The sparkplugs are black with engine running. How can I to diagnose this malfunctioning?.

This night I will put photos.

Jordi Mas

One more question- why were the carbs rebuilt? How was the car running before the carb rebuild?
George Butz

Jordi,

I don't think your engine has too much compression for the height of the pistons. This is self regulating due to the vented chamber above the pistons. The oil in the dampeners will keep the pistons low at the initial increase of air (Opening the throttle) this lowers the pressure under the piston and causes more fuel to be sucked up despite the fact that the needle is still low in the jet (this helps to prevent a 'stumble' as the engine picks up power).

As the air above the piston vents, the piston rises and the needle rises to provide the correct mixture for the throttle open condition.

When you activate your fuel pump, the pump should fill the float bowls until the float rises and shuts off the fuel inlet. That determines the height of the fuel in the bridge (as seen at the jet).

I'm looking forward to seeing some pictures.

warmly,
dave
Dave Braun

Hello. The mechanics recomended for my rebuild the carbs in paralel at rebuild engine. Before rebuild the engine, with the carbs pre rebuild, the malfunctioning is in the cylinders (oil consumicion), not in the carbs. This is the cause that I think the problem is in the compression. I think that is the unique aspect that changed. But can be incorrect.

Some photos.



Jordi Mas

another

Jordi Mas

last

Jordi Mas

Jordi,

I'm in the middle of re-building my carbs, so I'm new at it but I just had a flash of understanding. Something may be keeping your pistons from rising properly - a change to a stiffer spring for example, or excessive dampening. The lift, or low pressure, varies by the square of the velocity (V**2/2g), so keeping the piston low - thereby increasing the velocity over the bridge - will probably cause more fuel to spray from the jet than keeping the velocity constant (by raising the piston) and metering with the needle.

Jim
J Barry

There's something strange in your images. Generally, the fuel lines are between the carburetors and the head. Yours seem to be outside of the carburetors. I find myself wondering if the carburetors are in the wrong locations. Bud
Bud Krueger (TD10855)

Bud -
Front carb float lid needs to be turned 90deg anticlockwise. Rear lid is a front one, should have the inlet pointing 180 from where it is. Line looks too long. None of this is his issue.

Jordi-
"If the fuel pum is activated, the fuel out up to 20 cm. high"
If this is from the jet, then your float inlet valve(s) are stuck open or very badly adjusted for float level. Will certainly make it run very rich, I am surprised it will run at all.

This all appears to be a carburettor problem, nothing to do with compression.

FRM
FR Millmore

Hello. Thanks for all help.

Now, I put the needles lightly out, also I lossened the nut of cork seal: the fuel is cut at idle, but with engine hot the inlet of air is impossible regular. In this situation ther are a high rpm, I canīt low the inlet air because it is in top; the nuts of jets are at two face of end. I think that ther are a air inlet uncontrolled. I think that with this air inlet the pistons rise and leave pass fuel.
Jordi Mas

Hi,
Two things,
The angle of the jet lever in photo #1 looks at a strange angle as if the the jet carrier is too low,can you post a photo taken lower down?
Also if the carburetters have been fully rebuilt are the thottle discs in the correct way round.
Ray
TF 2884
Ray Lee

jordi, there have been posts by a lot of knowledgeable people here, so i am not sure i have much to offer.
i agree with Mr Millmore, carb piston height is determined by air flow through the carb and engine cylinder condition is not your problem.
what method did you use to measure your carburetor float setting? the workshop manual has you measure the float. Dave Braun has advocated a more accurate method of measuring the fuel level at the "bridge".


in your post you mentioned the fuel was 20cm high when the pump is activated. does this mean fuel is shooting up 20 cm above the bridge when the pump is on? when the pump is on the fuel should be 3-4mm BELOW the top of the bridge.

right now this sounds to me like a float level/needle seat sealing issue. the needle/seat is not shutting the fuel off due to misadjusted float level or bad needle/seat fitting.
best of luck. please let us know what you find.
regards, tom
tom peterson

Jordi,

Again,I'm new at this, but I'm exulting in my recent aha! moment of understanding how these things work. Did you replace your springs with heavier ones on the rebuild? If so, trying putting in the old ones. A lower piston (stiffer spring) will cause the mixture to be richer. The higher velocity due to the restricted path causes a much greater lift of gas into the mixture than if the piston were higher - because the so-called Venturi effect is non-linear (varies to the square of the velocity). Higher piston equals lower velocity and a leaner mixture.

Keeping the velocity more or less constant allows precise metering of the mixture with the needles.

Jim
J Barry

jordi, i'm not saying this is your issue, but of what material are your carburetor pistons made? i am sure someone will jump in here to correct me if i'm wrong, but brass pistons do not require the springs. regards, tom
tom peterson

Good point Tom, only the aluminum pistons have springs. The brass ones are much heavier and go without spring.
Willem vd Veer

Discovered failures: air inlet at throtle shaft (causes irregular rpm); link between jet levers with incorrect position (causes incorrrect back at normal position of jets after use); spring jet return very long (malfunctioning).

The pistons are of brass. Not use springs. I just want to slow the rise of pistons.

I need to know how stop the air inlet at throtle shaft without change for a oversize shaft, it is possible?

I donīt know if those items are causes of problem of this post, but i go to correct and comment the results.

I appreciate all ideas and new ideas.

Thank you very much.
Jordi Mas

Good day all:

With regards to Mr. Mas's photograph, showing both carburetters, installed. To me, and I am far from any Guru, it appears that both the float chamber lids are SU # AUC 1160's which were designated for the front float chamber.

The rear float chamber was fitted with an SU # AUC 1161 lid.

It is my understanding, that both lid petrol inlets, should face inwards, towards the engine. Thereby, the front inlet will be to the right and the rear inlet to the left of the respective chambers.

This way, as Bud has written, the petrol lines from the pump to the rear carburetter and from there to the front, will fall behind the induction pipe (aluminium air intake) and the head.

I may be wrong in this, as I have written, I am not even a gifted amateur in things M.G.

However; I will, once again try posting a photograph of the two lids. The rear lid is on the left. I Hope this will be of some help (both lids have top fixing "tickler pin" holes)

Cheers all; respectfully:
Jack Emdall, TC6768/TD3191, New Westminster, British Columbia, Canada

kernow

jordi, isn't your concern the carbs are running too rich? a leak at the throttle shaft would actually make the engine run lean. how did you determine the shaft (s) are leaking? from your description of an engine running too rich, i do not think a leaking throttle shaft is your problem.
to answer your question, just for testing/set-up you could seal the shaft with a fuel proof grease. you will need a more permanent fix.
i thought in your earlier post you said the carburetors were completely rebuilt. did you do the carburetor rebuild yourself? if the shaft is leaking and a shop did the overhaul, i would return them to the shop for a fix to a problem they should have performed at overhaul.
regards, tom
tom peterson

Jordi. Hei. lokking at your picture it seems to me that the 2 overflow tubes are welded together. am i wright or both yubres shall
go to the ground.
Thoralf. Norway TD 4490
Thoralf Sorensen (TD4490)

Jordi,

You say: "spring jet return very long (malfunctioning)".

This could easily cause your problem. Try pushing the jets back by hand with a warm engine and see how the engine runs, maybe after some more adjusting.

The throttle shaft wears more than the carburettor body. If you are lucky fitting new shafts will take away most of the air leak.

I bought an old single H2 carburettor for my YA because I thought the spindle showed no play AT ALL. Attached picture shows how some clever overhauler machined slots in a worn shaft and fitted leather or nylon bushes to it; it is on the car now, works very well and looks to be a professionally made kit.

Willem vd Veer

I'm betting on the brass pistons. Slowing the rise of the pistons is not something you want to do unless you want to make the mixture more rich.
J Barry

Jordi-
"If the fuel pum is activated, the fuel out up to 20 cm. high"
Tom Petersen and I have both asked what you mean by this - it is the critical point.

Thoralf's excellent observation may be the answer. The pipes from the float bowl tops do function as overflows, but their purpose is to vent the float bowls. If they are not open to atmosphere, fueling will be muy loco.

FRM
FR Millmore

Tom. The air inlet in the shaft throtle only cause irregular rpm but I want it correct. Thanks for your counseling but I donīt want return at the mechanics. My car suffers a kidnapping useless for a month each time. Please, not more!!.

Thoralf. I donīt understand your message. Iīm sorry, can you repeat?

Kernow. Thanks for you counseling. I changed this morning the position of lids but unfortunately there arenīt improvement. However, is the original position and so I will leave.

Willem. It is quite possible that this is the reason or combination of factors. I will go and tell.
I will try to repair the shaft with bushes of nylon or leather.

Ok, J. Barry. I donīt use the spring in the pistons, thanks.

Regards.
Jordi.
Jordi Mas

Jordi,

When you stop the air leaking by your throttle shafts your problem with setting the jet nuts should be fixed. It's this air that's keeping you from properly setting your idle.

There has been a lot of good ideas posted but I've read nothing that takes account of your car idling properly but not running once you've driven it for 60' as you mentioned in your first post. Also apparently overlooked was your comment later on that the car is very hard to start after it stops on the road. This doesn't necessarily mean that you've got a carburetor problem...it can simply be the float bowls have become heat soaked and the fuel has boiled out of them. The engine will have to cool down before it will start again...this is a common problem with our cars and you may need to add a heat shield.

Here are some questions I'd like you to answer:
1. Have you balanced your carburetors by disconnecting the throttle linkage between them and adjusting them separately?
2. With the piston/needle out of the carburetor and the switch on, where is the level of gas in the jet? Is it overflowing the top or is it 3-4mm BELOW the top of the jet?
3. While the car is out of gear, can you rev the engine to 2000 rpm and keep the engine running? If not, what happens?
4. Can you rev it to 3000 rpm and keep it running? If not, what happens?
5. Have you tried driving with the gas cap loose on the tank? There's a possibility that it's sealing too well and you're not venting enough air into the tank to let the fuel pump suck the gas out and send it to the carburetors.

Best regards,
Gene
Gene Gillam

First. I feel the damage caused by the tornado. Hope you're all well.

I say: "The carburetters give a lot of combustible and the engine stop when it is running in road more or less 60'. No oil in the spark plugs." And add: Very fuel in the sparkplugs.

Please, see this photos of exhaust. It isnīt oil, is fume black with cinder when i starter the engine next day.

Also: The carburetors has air balanced; when the switch on, the level of gas in the jet is 20cm eleved; when the car is out of gear, engine can to 2000 rpm and 3000 rpm and keep the engine running without problem. There are problem with 60ī running in the road.



Jordi Mas

Other photo.

Jordi Mas

Jordi, ŋdónde estás en Espaņa?.

In English: Jordi, ŋwhere in Spain are you?


Jesús
1953 TD
Valencia, Spain

J Benajes

The problem with the fuel carbon black in the exhaust on the floor is not uncommon, and doesn't necessarily mean you are running too rich at speed.

I'm still wondering what "If the fuel pum is activated, the fuel out up to 20 cm. high" means. Where is the 20 cm. measured from, are you talking about the height of the fuel in the float bowl? If so, that is a meaningless number. You should be measuring the height of the fuel in the bridge in the jet... see your 3rd photo.

Each float bowl needs its own overflow/vent tube. They can not be connected (as Thoralf and FRM (Fletcher) have mentioned.

How high is your altitude? Above 3000 feet try the AP needles.

Idle speed is 600-800 rpm. You should set the mixture at that speed.

If they jets are .090 orifice, they will be marked with a 9 on the head. If they are .100 they will have a 1 on the head. It should be impossible to slip a 3/32" OR a 2.4mm drill bit shank into a .090 jet as a test.

I hope this helps,
dave
Dave Braun

Jordi
I noticed your comment about unburned fuel on the sparkplugs, after the car stalls ....
That leads me to believe that , in addition to fuel problems, you may also have ignition problems....
The sudden cutoff of power at 60 (I assume you mean 60kmh, or 36mph), is pointing to failure in the ignition...
Possibly a loose wire in the circuit, that heats up , as you drive, then breaks contact....Might even be one of the small coil wires, either to the distributor, or the ignition switch. Or, even a bad fuse, with a loose cap.
Another item to check, is the "polarity" of the coil itself...
I just recently discovered, that on a breaker-points car, (-) side of the coil should be to the distributor, and (+) side to the switch...Battery polarity has nothing to do with coil polarity....This arrangement will give better spark , under load.
Best of luck with your search.
Edward
E.B. Wesson

Edward makes a good point. There should be a ground wire from the distributor to the block. See photo attached from my website http://www.dbraun99.com

The ground wire will provide a ground path to the breaker points under all vibration and running conditions. It was done by the factory, but many installers forget it on rebuild.

Warmly,
Dave

Dave Braun

Now he has said again "the level of gas in the jet is 20cm eleved" 20cm is 8 inches, and I assume "eleved" means elevated. That is well out of the carb!
IF the vent pipes are blocked, the fuel will just run through under pressure, there will be an airlock in the top of the bowls, so the level will nit rise enough to shut the float valves.

FRM
FR Millmore

edward, your info on coil polarity does not seem as complete as it could be. coil polarity does indeed matter. on a negative earth system the (-) post of the coil goes to the distributor. on a positive earth car the (+) pole goes to the distributor. regards, tom

http://www.chicagolandmgclub.com/techtips/general/574.html
tom peterson

jordi, please note FR Millmore's post above. the fuel level should be 3-4 mm BELOW the bridge (jet) WHETHER THE FUEL PUMP IS RUNNING OR NOT!!!! you should NEVER have fuel spraying up into the air out of the jet.
perhaps i am misreading your post, but if you are seeing fuel squirting up into the air..anywhere in your fuel system..this is wrong. are you talking about the fuel level in the float bowl? regards, tom
tom peterson

Jordi. Hei again. Re: my earlier post.sorry about the misspelling of some words, do to
old age.As I said in my earlier post, the 2 overflow tubes from
the float bowl lids also acts as FR Millmore
says in his post as vents from the float bowles to prevent vacum in the bowls
Regards
Thoralf. Norway. MGTD 4490
Thoralf Sorensen (TD4490)

Hi. I swear I've seen come from the jets 20 cm. rise with switch on and without pistons and needles. But today I donīt seen. Iīm sorry, I canīt do photo. I think that change position lids floats, rebuild springs of jets or another divine miracle that causes.

After, I rebuild the vents from the float bowles (to see photos).

The car is at 2000 feets.

Not cut at 60 mph. The carburetters give a lot of combustible when I stop after it is running in road more or less 60': about 1 hour. Iīm sorry the confusion.

The hole of jets is 2.2 mm (not 2.4). I think that the measure of needles is correct.

Tomorrow try the car in road again. Back to tell what happened.

Regards.

Jordi Mas

other photo

Jordi Mas

other

Jordi Mas

Jordi,
one thing to check is that the correct washer is under the overflow banjo. If a solid washer is fitted it will cause fuel to come out of the jet under pressure, the correct washer is cut away in places to allow air to vent.
The Moss-Europe part number is (12) AUC1928 on page 18 of this years catalogue.
Ray
TF 2884
Ray Lee


Sr. J. Benajes. Creo que lo dice por si puede ayudarme viendo el coche pero desgraciadamente estoy lejos de Valencia. Muchas gracias.

"I think that says if you can help me seeing the car but unfortunately I'm away from Valencia. Thank you very much."

Ray. I will change the washer under the overflow banjo, but there arenīt output fuel. Thanks.

Good News!!! Now there isnīt fuel in the spark plugs. The car accelerates well and starter after stop also well.

Remaining problems:
- Air inlet at trohtle shaft. Is necessary for idle.
- Correct position of floats. I had at 14mm. I think that the correct is 8mm.
- Correct sparkplugs (to see photo, please: NGK BP6HS (right) or CHAMPION L86C (left)).

But i had a problem today in road. I think that cause is the position of floats, but iīm not sure: I climbed a mountain pass at 3000 feets without problem. However, when descending (at gear 3Š or 4Š), the engine stop progressively. Return to starter at 3Š time and ,progressively, the engine back return at normal rpm. So until three time. When i descending the mountain (engine stop), I uploaded the lever of floats. And did not stop more until my house, but Iīm not sure that is the correct solution.

It is about happiness. I want to drive. Thank you all.


Jordi Mas

jordi, the service manual says the float setting is 3/8" or 9.525 mm. this is a starting point. the final setting is determined by the fuel height in relation to the top of the bridge.
after you reassemble the float chamber and activate the fuel pump, you measure the fuel height with the carburetor piston removed. you adjust the float to achieve the fuel level of 3-4mm below the top of the bridge.
you may have to repeat the process several times to get the correct setting. regards, tom
tom peterson

The Champion plug you have is a 1/2 inch reach plug. Most TDs use the 1/2 inch reach plug. The ones that use the 3/4 inch reach plug are the later heads. Many heads have been exchanged over the years so basing the depth on the engine serial number is not certain. If you have a "22952" somewhere on your head you probably have the head that requires 1/2 inch reach plugs.
Or, if you put a wire with a small 'L' shape at the end in a spark plug hole and measure the depth of the threads, and they measure about 15-16mm, then you need the Champions, however the recommmeded plug is the RL82C.

If instead, you measure a depth MORE than 19mm then you need the 3/4 reach plug. The prefered plug is also a Champion, the RN5C.

For some reason I find the cars like Champion plugs best... the 'R' in front of the designations is for radio supression, I don't think they make plugs without this feature.
Dave Braun

Tom
Thanks for the info....I really have already done the meter test on my positive ground TD, and the meter swung to the left (off the scale), with the coil (+) to the dizzy, and the (-) to the switch...
Thus the conclusion, that it should be reversed....
Allow my to quote an article from the Polytechnic Institute :

"Please note that the (+) and (-) designations have nothing to do with the battery polarity. It has to do with the phasing of the coil magnetic windings.
In transformer parlance, (-) designates the start of the winding , and (+) designates the finish of that winding.
Many mechanics INCORRECTLY believe that these symbols refer to the battery polarity.
Ironically, when they connect the + coil terminal to the ignition switch, and the - coil terminal to the distribtor points, in a NEGATIVE-ground car, it is correct, although, for the wrong reason! These same mechanics connect the + coil terminal to the distributor points and the - coil terminal to the ignition switch, in a POSITIVE-ground car, result in having an INCORRECT phasing of the coil."
So, interpret this as you wish, but I will stand by my original statement, with regard to a positive-ground car.
Edward
E.B. Wesson

Jordi
Glad you got it figured out...
Edward
E.B. Wesson

Hi. if it is helpful.

Summarizing, in my case i think what the carburators was to need:

To Adjust the nut of cork seals for a freedom move of jets.
Shorten the springs of jets for a functioning correct.
Take the needles lightly until out of pistons for a better contact with the head of jets in the bridge and that needles could cut the fuel.
To put the lids of floats in correct position
To put the overflow of floats in correct position.
Adjust the height of floats.
Change or rebuild the shafts of throtle for prevent the uncontrolled air inlet.

Other related aspects: I looked the cable in the distributor and it was until coil. Also, I think that the sparks plugs BP6HS donīt be the more correct.

Regards.
Jordi Mas

Jordi Hi again.
I am happy for you, and that you got it sorted out.keep us posted how you are getting along with your driving and send pictures of your car in the mountains if you can
Re: plugs. there canbe a difference in choice of plugs depending on hight over see level.
Also the mixture of air7FUEL is to be consideredwhen driving in thinner air.8 hight
over see level.
thoralf. Norway TD4490
Thoralf Sorensen (TD4490)

I'm not sure which plug you decided to use. From the photo it looks like you should be using the shorter (1/2") and not the longer plug. There is a lot of carbon showing on the last quarter inch of the threads of the NGK BP6HS which means to me they're uncovered in the combustion chamber (see how much cleaner the threads are closer to the body of the plug).
Gene Gillam

Hi. Today I measured the hole for sparkplugs and it has 15mm. Gene, You are right. The NGK is very long. I will try use the Champion recomended by Dave (when I have the time, now I am with the throtle shaft!!!).

Thoralf, I like doing photos of the car in the Mountain when I can. I still do not know what is the cause of stop engine at descending mountain.

Regards.
Jordi Mas

Jirdi Hi again.I think the reason for the engine stopping is when descending from the
montain is that the mixture getting too rich.
try to adjust the nuts 1 flat up.
Just an idea.
regards Thoralf Norway TD 4490
Thoralf Sorensen (TD4490)

Thoralf, that's what I thought, but for start the engine in pass mountain I had to enrich the mixture, even with the hot engine!!! However, I go up the pass mountain without problem.

Regards.
Jordi Mas

Jordi, on hot starts we often have to enrich the mixture because of the volatility of the fuel and the vapor lock in the carburetor. But running it rich often gets past the vapor.

I wonder if with the higher compression engine you need a heat shield between the exhaust manifold and the carbs. Can you try wrapping the carburetors with a wet cloth and seeing if that eliminates the problem? If so you may need to construct a heat shield.

warmly,
Dave
Dave Braun

Dave. Thanks by you counseling. Now Iīm rebuild the throtle shafts and when it are well can try the car. Report results.

Regards.
Jordi Mas

This thread was discussed between 18/05/2011 and 28/05/2011

MG TD TF 1500 index

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