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MG TD TF 1500 - Too Rich

I finished "Winston" my 54 TF last July and have thoroughly enjoyed driving about 1000 miles since!
Now! My problem is that the 11/2" carbs are running WAY to rich. I have now scoured the archives and many other sources to find the basics to tune these H carbs. The base line, to start, seems to be 9 flats down or about 70thou down from the bridge then to tune from there. I have Standard Needles and no matter what I am still too rich.
Now I could use some advice from those T Series owners who live and operate their T's at high elevations. I live at about 3700 ft and know from my flying days that leaning the engine was critical. Thus for those living at higher elevations, what needles are you are using and how many flats down are your jets?
Thanks in advance for your help!
Best regards
Rod Murray (Nelson BC)
Rodney G Murray

Don't know if your TF runs the pancake filters or oil bath, but if it is the latter, doublecheck your oil level isn't too high.

Next, I'd suggest going over Dave Braun's instructions

https://www.dbraun99.com/SU%20Carburetor%20tuning%20gen%20rev%20d%20161127.pdf

and the multitude of rebuilds compiled

https://www.dbraun99.com/SU_Carburetors/
JIM N

Idle mix is something you can adjust. Running mix is all about the needle. Is it just at idle that you are rich? If thats the case have you run the adjusting nut up as far as it will go? Stock SU fuel pump? How old are the jets and needles?
Check that the one or both of the floats are not bad and filled with fuel. I live at 4800 ft and have never found a need for a leaner needle on any SU carbed MG here.
L E D LaVerne

Hi Laverne
"Winnie" runs rich at every stage. Needles(GJ)/jets new. Never thought to check floats. Stock SU fuel pump.Didnt want to run the nuts all the way up for fear of crossing into "too lean" condition.
I'll disassemble and try again.
Thanks for the help!
Rod
Rodney G Murray

Even with a too rich needle you should be able to get a satisfactory idle mix. Follow the manual in setting the mix. use the lifting pin and if the engine dies it is too lean. If the engine speed rises and stays there it's too rich. If the engine speed increases and then settles back down to where it was it's just right. Blip the throttle between tests. Once you have finished with one carb try the other. Once thats done sync the air flow between them. Once you get that done replace the plugs and go for a long drive and then examine the plugs.

If you can't get a correct mix at idle and do not find a fault with the floats, check their setting. I use a 7/16" bar to set mine. Have groose jets? Many have reported issues with those in recent times. Thats just a place to start.
L E D LaVerne

This thread was discussed on 03/06/2022

MG TD TF 1500 index

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