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MG TD TF 1500 - Carbuettor adjustment TF1500

I am now happy with the electrics and timing (many thanks to you all) and am moving on the the carbs.

It is clear (both from the plugs and ColorTune) that she is running pretty rich.

I have tried to wind up the adjustment nut, but it is near unreachable, and also unshiftable with the fingers (even that requires six joints on each finger all double jointed); probably the reason it was not.done by the PO.

So the baisc question is, does a special tool exist to work on the nuts, or is it a side panel off job, which looks more like taking off the wing, or even is it easier to remove split pins and or even the whole carb?

Ian Bowers

Ususally an easy finger job with the air filters removed Ian. You can purchase an SU adjusting wrench if you find that still doesn't work. They come in most SU tool kits.

Thanks LaVerne

When you say "with the air filters removed" presumably this includes the back plate as well, which looks difficult to get at the rear nuts. I still have the original Vokes filters.

Ian Bowers

I use the small jet wrench from the SU Tool Kit on my TF 1500
This is also available separately from Moss
(#386-400 5/16 W SU Jet Wrench in US Catalog, $2.85)

Some work is easier if you remove the air filters first

You need to do this to sync the carbs anyhow since you are fiddling with the jets

A float level adjustment may be what is needed rather than jet adjust
In any case start here
Don Harmer

Right! Air filters now off, and it would appear that the adjusting nuts are hard against the top surface.

GJ needle in one pot, the other one is too stiff to shift without damage, but my memory is that these are 'right'. No colour on the spring, but believe this should be 'blue'.

Looks like time for a careful study of D dB's treatise on tuning carburettors; but that is for next weekend.

Those who still have serious daylight left, enjoy!

Ian Bowers


Your jets are probably worn, due to a PO not centralising the needle! - an SU mystery known to few! I'm joking - easier to do than explain!

Suggest repair kit from Burlem, quote car and model, this will include new jets, needles and 'cork' seals large and small - the other gaskets are not so critical but worth keeping.

SU guidance in WSM is pretty good, see Archives here, stressing the importance of getting the fuel level just below jet by adjusting the float level. Forget the round bar under the brass float lever, except as a starting point. Rotating the float bowl also affects the fuel level, so get them where you want them and tighten the big nut firmly!

Good luck,


J C Mitchell


You may want to check out the carburetor tuning manual on my website, in the technical section, under "The detailed instructions I send out to clients after I rebuild their carburetors."

It is a PDF there for downloading.

Dave Braun

Adjusting SUs on a TF is almost as bad as fitting the woodruff key to the pedal shaft (but not really THAT bad).

Over 57 years of ownership, I've made some simple mods, the first of which was to replace the original TF air filters with a pair of simple, short velocity stacks. It will be argued that this admits more dust etc. but this is my 4th engine and I can't really see any bad effects. But with the short velocity stacks, I did definitely enjoy an improvement in performance. The revs rise noticably faster than with the air filters.

Here are a couple of really great web-site on the SU:- There are several valuable links so be sure to check them out.

Another favourite is the Minty Lamb SU chart. This is a dynamic site and your mouse action will help make the comparison. Have a look at:- also gives values for combinations of springs, needles and jets.

There are many others by the Miniforum, MG experience and others. The reference to the station, usually refers to the increment in 1/8" steps.

In closing, I can rember paying 25 a needle at our local Lucas dealer. I have no idea what they sell for today.

Gord Clark
Rockburn, Qu.
Gordon A Clark

An SU tool given to me by a friend who used to own a TF back in the 1960's. (I usually use my fingers too).


Matthew Magilton

It should not be too difficult to get the air filter backing plates off. I believe a 12 mm spanner will fit. Once a bit loose, use fingers. When I need to adjust my carbs, I always remove the entire cleaner body from the engine side. The bolt heads on the "cover" side are even worse to get at.

'54 TF
Tom Norby

This thread was discussed between 21/08/2011 and 22/08/2011

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.