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MG TD TF 1500 - Carburetor

Okay, not sure if I'm diagnosing the problem right, so I'll give the symptoms and what I think the issue is.

Symptoms: The engine kind of "flutters" (pudda-pudda-pudda) at high RPM (don't know the RPM number as the tach doesn't currently work). In the top gear I can get up to 50 MPH but if I hit any kind of incline I start to lose speed and power.

Possible solution: I think the carbs are not balanced. (I recently repaired the linkage between the two.)

Does this sound like the right diagnosis? If it is, anyone have any good suggestions on how to balance the carbs?

Thanks much.
A Bartlett

Is this a new problem or is it one that the car has always exhibited during your ownership? You should be able to get to at least 80 MPH with badly out of balance carburettors. Timing or swapped plug wires could be the problem.
George B.

This is a new problem. I was able to get the car up to about 68 MPH when the carb linkage was broken. The only things changed in the engine were the following: new gasket for the valve cover; fixed carb linkage.

I fixed the starter (after much gnashing of teeth) by just giving it a turn to free it up, so nothing changed there.

The engine idles fine, and the oil pressure seems okay. None of the wires was changed.

Because of all that, I assumed it was the carbs. What other areas should I look at given the above?
A Bartlett

The first thing to check is that both butterflies are opening all the way when the throttle pedal is depressed. No need for the engine to be running to do this. Are you indicating that you could go faster with only one carb opperational than with two?
George B.

Yes, I could go faster with only one carb. What do I need to do to ensure both butterflies are opening? (I'm new to all this.)
A Bartlett

Yhe manual gives a good method of balancing the carbs,, If you follow it, you should get good results,,, Just keep in mind that 99% of carb problems are in the ignition system !!! ie moisture in the cap, capacitor, points, wires, plugs etc !!
SPW
Steve

Worst time that happened @ top gear, highway...
discovered all 4 sparkplugs were loose - don't ask. ;)

Previously, also occurred when I decided to
try increasing the plug gap to 0.8mm - ran
better at lower speeds but 'fluttered' on
the highway. Disappeared when regapped to
0.5mm, so think coil might not be up to task.

Had slight reoccurrance in July... so gave
it a new condensor to suit the 2-mth-old
new points. Seemed to cure it that time.

Could be also fouled sparkplugs.


Have yet to even touch the carbies... 8)
Will

It is worthwile to check that the bottom of the float chambers are clean - free of any sludge that comes through from the tank. If the line through to the base of the carburators is partially blocked, it will affect running at higher speeds.

Peter
Peter Falconer

It is said that 9 times out of 10, carburation problems come from the ignition. I can't vouch for that, but it makes sense.

I'd look at the break points and at the distributor.

Denis
Denis L. Baggi

This is one hypothesis: the carburettor that was disconnected doesn't work, so when it was reconnected it caused a lean condition and made the engine run worse. Maybe one of the S.U. gurus will comment on verifying the operation of each carb for Andrew.
George B.

Perhaps it is in the fuel pump? If the fuel pump was delivering enough fuel for one carb and then you "added" the other, it may not be putting out enough fuel for two. I had the same symtoms with a B GT many years ago. I changed the fuel pump and all was fine.
Regards,
Ron
Ron Boisvert

Get a copy of the New England T Register "The T series Handbook". It has an excellent basic to advanced section for the carbs. The article explains all functions in detail, and is great for total novice to old hands (who can never remember if lifting the piston/idle speed up is rich or lean!). Check fuel level in bowls, make sure carb pistons move freely, make sure both butterflys open fully and about the same time, check for air leak (carb-manifold, manifold to carb), etc. Make sure when throttle opened by pedal that both carbs open and stay- if the center link clamp is not tight enough, the front carb will gradually close, etc.
George Butz

This thread was discussed between 14/10/2003 and 17/10/2003

MG TD TF 1500 index

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