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I am interested in aquiring a set of carbs for my TR3a. I have webbers installed at the moment. I understand that originally, the TR3a should have a pair of SU H6 carbs. The inscription on the carbs that I am interested in, have the mark

'AUC 6040'.

Question.  Does this reveal that these carbs are H6 or is this a general inscription. If so, how can it be determined whether they are H6 or H4?

I would be grateful for your input on this question.



TS 61652..........nearly finished!

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Hello, here is what moss say about this:

These carburettors originally had triangular aluminium tags on the float bowl lid. These tags were stamped with

the SU identification number for that specific carburettor installation. For simplicity, we use these numbers found

on the tags in our application column. If your carburettor tags are missing, use the information here (with our

illustration) to identify your carburettors. The dimensions 11/2" and 13/4" are measured at the throttle disc end

of the carburettor body, as opposed to the air/fuel passage where the air filter is fitted.

H Series Carburettors cont'

AUC721 Type H4 (11/2") TR2;

These are identified by the fact that each carburettor is mounted to the inlet manifold with only 2 studs

(see Inlet manifolds on page 118)

AUC786 Type H6 (13/4") TR3 to aprrox. end of 1958;

Each carb' is attached to the inlet manifold by four studs. The float chamber on this application has the

‘banjo’ type fitting - shown on page 111 with illustration numbers 133 to 142.

AUC878 Type H6 (13/4") TR3A from aprrox. 1959, TR3B and TR4 to CT21470;

Each carburettor is attached to the inlet manifold by four studs. The float chamber on this later carb'

has the fuel inlet pipes joined to the carburettor by a ‘push-on’ piece of rubber.

Regards, Guy

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Hi Chalky


H4 carbs only have two mounting holes, H6's have four. To identify your H6's have alook at page 19 of the Moss catalogue. They list them as AUC786 or AUC878.


Regards.   Les.

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Hi Chalky, i have  a set of  H6 SU's complete with manifold, throttle linkages, and K & N filters for sale if you are interested. They were refurbished by Racetorations and used on a tr3a for about a year. The numbers are AUC 878.

Drop me an e:mail if you are interested


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Hopefully Burlens will have been able to tell you where your carbs came from.  If not, a chap at BHB in Southampton should be able to help. (023 8022 0182)

My car has HS6 carbs (with the later biased needle) which originally came from a '75-'76 Triumph 2000.  Ref No.AUD676. I believe that the 2500 from this era also had HS6 carbs and might be a useful second hand source.

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Thanks everybody for your input. I have found out by visiting the Burlens website that they are H6's.


Chalky :D


TS61652 1959 TR3a almost on the road !!!

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  • 5 years later...



no idea what the extra fitment is to your carb, but not Peerless and I rather doubt anything else Triumph.


AUC6040 is a generic number for H6 bodies - individual carb specification for a particular application is tied down by a subsidiary number, AUC878 in the case of TR3A, originally on an alloy tag affixed to the carb.


Suggest you consult an SU specialist such as






Bear in mind these guys get inundated with enquiries about old carbs, largely by folks hoping to make a few bob on ebay. I wouldn't bother emailing, I'd make the effort to ring them up first and if necessary then email a piccie.





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Heres the picture.. any ideas???



I've not seen the like of this before.


Could be a bodged H6 for use on a super charger, the addition being a some sort of pressure relief valve.

Edited by BlueTR3A-5EKT
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Very bizarre. I don't think it is a blower wastegate. I would rather see it as an adjustable PCV. First time I ever see this. You live and learn.


H6 are long-bodied to go with short manifold (TR2 3 4), HS6 is short-bodied to go with long manifold (TR4A), fixed or biased needles. 3 bolts air filter attachment is Volvo HS6.

Strombergs are for TR4 between march and october 1963 (roughly).





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Intriguing addition and not factory original on any TR, Italia, Dove, Morgan, Peerless, Warwick etc. Some TR engines were marine converted, but I can't think of any such mod to the carbies.


It looks like it takes about 1/2" rubber hose, which is too large for water injection or nitrous. Nothing to do with supercharging either, as they generally use one 2" HD8 horizontal SU.


I doubt it's for a PCV valve, as an SU carby won't operate correctly with any pressure drop between the needle and the butterfly.


You've shown us the rear carby - is the fitting on the front carby as well ?.


Baldrick could be on the money. Considering TR engines often run on, perhaps it's a gadget to dump cold air into the carby. I've seen such a thing operated by a relay that opens a valve after engine switch off, but it was plumbed into the manifold.


Anyhow, you can plug the hole, or just get another body, and still get to use that pair of carbies.





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