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MG TD TF 1500 - Carb Identification

My TD has carbs marked with PPC 3478 on them. The pistons are brass and the bore is around 37/32nds.

I also have some carb parts that appear to have the same body, but they have different bore and metal pistons.

One set is marked AUC 6010. The piston is aluminum and the bore is 33/32nds. They also have a heavy weight in the piston skirt.

The other set is marked AUC 6070 and has aluminum pistons that are identical to the TD piston and bore 37/32nd.

Externally, all three look very similar.

I know the bugeye used a similar carb, but did the TD carb change from 50 to 53?
Bruce Cunha

Bruce - I don't know all the answers to the questions that you posed other than to say that 3478 is the number that Burlen Fuel gives for the body of the H2 carb. Neither of the other 2 P/Ns show up in their catalog. The same carb was used on the TD from 1949 through 1950 and any differences in the different bodies would be rather subtle ones. The only other differences would be in the carburetors used on the TD MKII, which is a H4 carburetor. The brass piston would have been used in the early H2s as found on the TCs. The aluminum piston with the weight is on most of the TDs. The all aluminum may have been used on some of the Spridgits, but no on the bugeye, as that used a H1 carburetor and would have had a spring acting on the top of it like in all of the later carburetors. By the way, if you don't already know, H is the basic style of the carburetor with the numbers (1, 2, 4, etc.) being the bore size in 1/8 increments over 1 inch (H1 being 1 1/8", H2 being 1 1/4" and so on). You might be ab e to get some better answeres to your questions by e-mailing Burlen Fuel, since they are the folks who now make the SU carburetors. I had a tour of their facilities while in England recently and i was quite something to see the crates of carburetor bodies that they have in their store room. Burlen Fuel can be found at http://www.burlen.co.uk/. Good luck - Dave
David DuBois

To clear a little confusion, the sizing is as Dave states, but it is measured at the throttle bores. These are about 3/32 larger than the bore on the air inlet side, on H series carbs; on HS, the inlets are the same as the throttle bore. The AUC60** is a basic casting number, not a part number; they were machined for different apps, and the resulting part no. etched on a flat pad following the molded in AUC60**. Bruce's AUC6010, at 33/32 inlet, should be 1 1/8 throttle bore; hence H1, probably a bugeye, which used the weighted piston. His other two examples with 37/32 intake, should be 1 1/4 throttle, or H2. The brass pistons were heavy, and some later cars used weighted alum. pistons to match this weight; later still springs were used instead of weights. I seem to recall finding all 3 variants on original TDs, but it's been a long time! Dave's statement on the MkII TD as having the H4/1 1/2" carb is right; these may have had the same body as MGA, casting AUC6020.
FRM
http://www.usachoice.net/gofanu
FR Millmore

I recently picked up (cheap) two NOS bodies #s 6060 and 6070, both 1-1/4", one with piston lifing pin, both with vacuum ports and one external hole (same place TF carbs have 2) at air filter side. With minor modification should work fine on a TD. A friend has a patched and rigged stripped float bowl thread and we plan to replace with one of these bodies.
George Butz

George
Its worth checking the flange to flange dimensions. I am going through the same process of replacing a body due to stripped float bowl thread. I have bought a AUC 6080, to replace a 3478, and find the above dimension is 2mm longer. Now do I replace both bodies. I was told that 6060 and 6080 were very similar to the 3478, which in my limited experience have a tendency to distort.
henry

Henry, if the total length is just 2mm long,a machine shop could skim the face(s) that much. I will measure, as that would keep the air cleaner manifold from aligning properly. George
George Butz

I found Davids advice about contacting Burlen (http://www.burlen.co.uk) good advice. I found that they do not make the brass piston used in the early TD any more. They also identified the AUC 6010 as a morris minor or triumph hearald carb.

Bruce Cunha

This thread was discussed between 28/10/2004 and 01/11/2004

MG TD TF 1500 index

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