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MG TD TF 1500 - Carburetor Rebuild Instructions

I've been reading a number of posts which reference experiences while rebuilding carburetors. I'm thinking about taking on that as one of my next projects. But being the propetual newby that I am and knowing nothing about carburetors, I need some guidance.

A number of posts refer to a manual or book with rebuild information. Also mentioned is a special tool or tools necessary in the rebuild. For someone that has never done anything like this; What is the best manual/book (or two) for me to acquire in preparation for the caburetor rebuild, and what tool (or tools) would you suggest are necessary for the job? I am going to assume that I need to get the Moss Carburetor rebuild kit (unless someone suggests differently).

As usual, thanks for the help and patience. I'm sure this will only be the start of a number of questions (but first I need to become smart enough to even know what to ask).

D P Earles


The Haynes SU carburetor book is about as good as it gets.

Centering the jet is about the only thing that requires speical tools when rebuilding the carb, but you can do it by just careful assembly. So skip the jet centering tool.

The only other special tool needed is, if there is a loose throttle shaft in the body, in which case you will need to rebush and ream, or ream and go oversize on the shafts. Since this is a once in a lifetime job (almost) just have a machine shop do it if the shaft is questionable.

Finally, most of the other tools are related to balancing and setting the mixtures. I use a Unisyn to balance and a dial caliper to set both the float height and the initial jet setting. The SU tool kit is next to worthless (well not exactly, it's all what you are used to) and I find the process of setting the fuel height with a 7/16 bar to be so unreliable that you have to have a willing suspenesion of disbelief to use it.

Just mark the parts prior to disassembly, don't mix them up carb to carb, unless testing reveals that they will operate better switched, and break fastners loose very, very carefully.

If you get really stuck, email me off board and I will help out... I've been doing quite a few carburetors for fun and profit lately.

Hope this helps,
Dave Braun

I've been working rebuilding my carbs. I just used the workshop manual and the moss catalog diagrams are helpful. But the biggest help was going to youtube and searching under "university motors"... Mr. Twist has an excellent series of videos about various aspects of SU carb rebuilding.

That being said, I've put everything together and she hums along nicely except for one thing - there's fuel dripping from the bottom of the float bowl. What's the most likely problem here? the big rubber washer which the float bowl mounts to the carb body?

Tips gratefully received!

G M Baker

Maybe because there isn't suppose to be a big rubber washer under the float bowl! There are suppose to be one fiber washer under the bolt head and a stack of two fibers with a metal washer in the middle between the chamber and carb body. Rubber ones were for later carbs? George
George Butz

Be very, very careful tightening the bolt under the carb body (ask me how I know). Only a few very soft threads there, and they WILL strip with too much torque! I used a very thin smear of permatex blue hylomar (it never hardens) on all washers after fighting leaks everywhere. Not a single leak since.


L Karpman

Patrick, IMHO one of the best places to start is by getting a copy of the SU Carb Rebuild Video sold by Moss (211-036, $44.95). Lawrie Alexander does an excellent job of showing how it's done and, you can rewind and play it over and over while you have your carburetor(s) in front of you. Bud Krueger
Bud Krueger

Not to encourage GM's threadjack, but George is correct about the big rubber washer. The Hs in the MGA had neoprene washers, and some TD owners converted to MGA float bowl attachments to solve leaks. I can tell you from personal experience that the neoprene set up only works marginally better than the correct set up. But you can order the MGA set up from Moss.

Dave Braun

Apologies for the thread hijack! The Moss video sounds like a good investment... I'll look into that myself.

G M Baker

To augment Dave Braun's comment -- if there's only slight looseness in the throttle shaft, you can often get buy without bushing the carb but only replacing the shaft. Remove the throttle plate and slide the shaft out enough that an unworn portion of the shaft is riding in the bushes. If the looseness goes away, it's the shaft that's worn and not the bushes. All you need is a new shaft.

I'd disagree with his comment on the SU toolkit. Or rather, he has it backward -- the Unisyn is nearly useless; it's the SU toolkit that makes balancing a breeze. And the toolkit comes with a jet centering tool. ;-)

I don't know if the Haynes SU book covers doing a damper piston drop test, but I know it's in the Bentley mgb book and it's in the SU repair book as well. You definitely want to take the time to do it and it's easy to do. Just because you've been careful not to interchange parts doesn't mean that the previous owner(s) were, and the drop test will help you spot problems if parts have been mixed up. (The drop test makes sure that the pistons are matched to the domes and have the same rise and fall rate.)
Rob Edwards

This thread was discussed between 20/11/2009 and 21/11/2009

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