TR6 Possible rebuild of SU-HS6 Carbs for TR6

[jmayled]

I've recently acquired a set of used SU-HS6 carbs that I would like to install into my '75 TR6 in place of the ailing Zenith-Strom's.

The SU carbs are stamped with "AUC 1346" and "AUC 8490". Is it possible to rebuild these carbs for use with a TR6?

If so, can anybody provide me with some good pointers? (A copy of the Haynes Weber / ZS / SU Carb Manual is en-route to me.)

Best Regards,

Jon.

 

[71tr]

I've just replaced my old and worn ZS carbs with a newly rebuilt pair of SU-H6's. These are a direct bolt-on replacement for the original zeniths. Rebuild kits are available but I had mine done professionally by Jeffrey Palya. He does good work and micro-polishes the units to better than new (see photo). https://paltech1.com/index.html

 

[Banjo]

WOW those look great. Do you know what he uses to "micro polish" them. It also looks like he plated all the hardware.

 

[Keoke]

HI Jaymayled, There should be two small aluminum tags fastened to the top of the float bowls with the carb type number on them. However, you will have to match the carbs to your engine because as far as I know the SU is not original to the TR cars.---Fwiw---Keoke--?

 

[piman]

Hello Jon,

S.U. HS6 models were fitted to the following Triumph cars, which use the TR6 engine:- 1975\76 2500 TC. they used the BDB needles, part no NZX 8002 or a BDU which is NZX 8019.

For more detailed information try this site:- www.burlen.co.uk, who manufacture and supply S.U. spares.

Alec

 

[tr6lover]

i have put hs6's on my tr6. here is the deal, any hs6 will bolt up to the manifold, the difference is in the float chambers. the ones you need, need to sit level, not on an angle like most do. you need a set of floatbowls from a spitfire or give apple hydraulics a call as he normally has some in stock. it will work if you use the floats that do not sit level, but as they do not sit level they will always force some fuel into the carb and make it run rich.
Randy

 

[71tr]

tr6lover,
i don't follow the issue of float bowls not sitting level. sure, the su float chambers can be tilted to accomodate fitment but how does this affect the amount of fuel flowing into the combustion chamber? seems that the fuel flow into the carb is controlled by the metering needle and jets which should not be affected by a slight angle on the float chamber. i can see this having some play in the float and shut off valve at the top of the bowl but this does not impact fuel flow into the carb so long as fuel is available in the chamber. pardon if I'm not clear on this.

 

[Keoke]

HI Piman, I could not get Burlen's site up. But what ever HS6 carb type they show for the TR6 engine our lister[Jon] will be required to duplicate using the ones he obtained.---Keoke

 

[piman]

Hello Keoke,

I just checked the link and it worked for me just now. It could have been down when you tried it?
That is the point, although there are few major variations in practice. Needles are one, and as mentioned the float bowl adaptors, which set their angle is another. Burlen will have the correct specifications, but I'm sure that there must be other specialists in America who can advise and supply the necessary parts. The above plus overhaul kits weigh next to nothing so shipping is not an issue.

Alec

 

[piman]

Hello all,

further to my last post and as I had the Burlen site up I looked further and they list a conversion kit for the TR6 from Strombergs to SU. Their part number is FZX 3045. A full list of the components is:- https://www.burlen.co.uk/partList.aspx?carID=9647

The needle they have for this conversion is a BAG, which is part number CUD 1106.

Alec

 

[SpannerMan]

[ QUOTE ]
tr6lover,
i don't follow the issue of float bowls not sitting level. sure, the su float chambers can be tilted to accomodate fitment but how does this affect the amount of fuel flowing into the combustion chamber? seems that the fuel flow into the carb is controlled by the metering needle and jets which should not be affected by a slight angle on the float chamber. i can see this having some play in the float and shut off valve at the top of the bowl but this does not impact fuel flow into the carb so long as fuel is available in the chamber. pardon if I'm not clear on this.

[/ QUOTE ]

FWIW I have the TR3 type SU H6 (not HS6) with the cast twist in the floatbowls. It looks a little odd but works OK. I had to seal the lids with some sealant because the joint tends to be wetted by the fuel more in this configuration. Pete

 

[tr6lover]

hi all, the issue with the floats sitting level isnt just a matter of getting the correct adapters, the fuel level in the floats that sit level is much higher than the ones that sit at an angle and even if you make the ones on an angle sit level then the float height is too high and therefore forces fuel into the jet and right out into the carb. the tops are the same but the level float sits lower so it doesnt force fuel into the carb thats why it would run rich if you just used the floats you have. give apple hydraulics a call and joe curto can explain this all to you.
Randy

 

[71tr]

the adjustability of the float bowl angle on SU carbs is there to compensate for the natural angle of the carb mounted on the intake manifold. ie..the carb is naturally tilted so you adjust the float bowls to level.

regardless, the function of the floats is exclusivly to open and close the valve from the incoming fuel line. it has nothing to do with richness of the fuel mixture or even flow into the carb itself. that is managed by the throttle, jets and metering needle. if your carbs are running rich it is not an issue with your float bowl. so long as there is fuel in the bowl and it is not overflowing then your float valves are functioning correctly.

 

[piman]

Hello Randy,

the idea is that the float chamber is always vertical, whatever the angle of the carburettor and the level is always the same.

Alec

 

[tr6lover]

the point i am trying to make here is that when you stand the float bowl up the fuel level sits higher, a lot higher than the floats made to sit level. you can not adjust the float enough to compensate for this. since the fuel level is much higher it forces the fuel into the carbs because of the fact that the jet is now sitting lower than the level of the fuel so it is being force fed into the jet. this is a problem and i have seen it first hand. i have talked to quiet a number of people who have done this conversion and this is always the case. the mount for the float bowl is in a different position on the floats that sit level so the bowl sits lower on the carb than the ones on an angle.
Randy

 

[jsneddon]

[ QUOTE ]
regardless, the function of the floats is exclusivly to open and close the valve from the incoming fuel line. it has nothing to do with richness of the fuel mixture or even flow into the carb itself. that is managed by the throttle, jets and metering needle. if your carbs are running rich it is not an issue with your float bowl. so long as there is fuel in the bowl and it is not overflowing then your float valves are functioning correctly.

[/ QUOTE ]

nope.

Take a funnel and a hose and hold the end of the hose higher than the top of the funnel in a U.

fill it with some water. As you raise and lower the funnel (The float bowl) the level in the hose (the jet) goes up and down.

The function of the float is to ensure the proper level of gas at the jet. If the float is too high then the gas wants to seek the level of the float and you have more fuel than designed at the end of the jet. if you look at it with the top off the carb you will see the fuel just sitting to the top of the jet.

Yes there is a vacuum through the bore but I'm of the understanding that fuel getting to the jet is more a function of gravity rather than suction.

 

[jmayled]

Thank you all for your feedback. Above the AUC numbers stamped in the body of the carbs, there are no other identifying tags present. My assumption here is that as these carbs have a 1 3/4" opening, they are definitely of the HS6 family, however I would still require the correct needles and a general rebuild kit assigned to the '75 TR6. Can anyone clarify this for me?

In lieu of that and based on the possible complexities with rebuilding these older model SU carbs, I may ship them to Paltec for a professional rebuild / trade-in. (Jeffrey Palya's craftsmanship looks exceptional!)

Thank you PIMAN and 71TR for the web links.

 

[gbtr6]

Hi, I have the HS6's on my '74. I was able to take the float bowls off, and remove a piece that looked like a pie slice if I remember correctly. Then I put them back together with this peice reversed. It removed the tilt and they are very nearly level. I haven't changed the needles and they probably need it as there is a flat spot. Other than that they are great. Perry

 

[SpannerMan]

[ QUOTE ]
Thank you all for your feedback. Above the AUC numbers stamped in the body of the carbs, there are no other identifying tags present. My assumption here is that as these carbs have a 1 3/4" opening, they are definitely of the HS6 family, however I would still require the correct needles and a general rebuild kit assigned to the '75 TR6. Can anyone clarify this for me?

In lieu of that and based on the possible complexities with rebuilding these older model SU carbs, I may ship them to Paltec for a professional rebuild / trade-in. (Jeffrey Palya's craftsmanship looks exceptional!)

Thank you PIMAN and 71TR for the web links.

[/ QUOTE ]

If you post a pic of the carbs you have, or just a good shot of one of them, it would help give a positive ID on what you have. If they are 1.75" SU's they are definitely XX-6, a question would be what is the XX and anything specific to do with the application (which vehicle they came off). Pete

 

[jmayled]

The carbs from what I can fathom are from a Volvo P1800. Hopefully someone maybe able to clarify the carbs from the attached pictures?