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Triumph TR6 - SU HS6

Can someone explain the differences between the 175's and the HS6's. I have several questions reguarding these carbs (1)Can the 175's be modif. to get a better performance from them (2) Did any of the 6's ever have the HS6's from the factory? (3) can one replace the stock 175's with HS6's? (4)If so what is the gain? (5) What cars did the HS6's come on (6)and finally Are the HS6's any easer to maintain and rebuild that the others. I am at the point of choosing carbs for my 6 motor and would like to choose the right one the first time..... Thanks
Jeremiah Randolph

1.In general the two carbs will have practically the same performance capabilities, however the SUs are much easier to adjust and tune. The CD175SE found on Federalized TR6s have several emissions features, mostly in the cold start and idle circuits, that tend to wear with age and create problems, mostly at idle. A set of correctly rebuilt Z-S will function very nicely however.
I actually prefer the early Z-S CD175s found on the TR4 because they are much simpler in design and are better than SUs in some ways.
2. Not to my knowledge.
3. Yes. The SUs bolt right on. Moss sells a kit, as do most TR specialists and Burlen Fuel Systems.
4. The gain is that they are easier to adjust and when adjusted will stay that way for a long time. IMHO a heat shield is good idea due to the proximity of the exhaust manifold.
5. HS6s were found on Volvos, and many British cars.
6. Generally, yes.
A Blackley

As a follow-up to Item 5, I forgot to mention that the TR4A, from about 1966-68 had SU HS6.
Contact Jeff at Paltech: , he should be able to set you up at a decent price.
A Blackley

Hi Jeremiah,
I am currently replacing my ZS 175's with SU HIF's...I am waiting for a part in the mailin the next couple of days then the carbs go on.I have never been really happy with ZS and ..they could run great for weeks then one day act up and without even opening the hood ! My friend had the same problem last year and bought new SU's and swears he'll never take them off ! He said the are great worry free carbs..I'll let you know as soon as we get some nice driving weather...If it's dry next week / week-end I'll be testing my SU's !
Having had both types of carbs apart the SU's are easier to work on with less tricky parts.
Based on other friends who have them and talking to a guy who rebuilds carbs it seems SU's is the way to go..apparently SU wanted to charge Triumph double what MG payed for the SU carb so Triumph designed the ZS as close as possible to SU's without breaking the law and had Zenth build them.

Hope that gives you some food for thought

Charlie B.

This thread was discussed between 19/03/2006 and 20/03/2006

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