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Triumph TR6 - HS6's on TR6

Hello again folks: I am looking for a bit more performance from my 74 TR6 (US). I am installing a set
of HS6's from a Volvo B20. I bought a rebuild kit
for a TR4, and found the needle does not fit the jet.
The TR4 jet(.090) is smaller than the Volvo jet(.100).
Does anyone have any opinion on which way to go?
Should I convert the needles to fit the .090 jet, or
get .100 jet assemblies? Any information would be
appreciated, as I am weary of trying to improve the
Strombergs performance.

Dave L.
Palatine Illinois
DG Lazarus

You do know the Volvo ones are not straight bolt up don't you?

Repeat after me:
Joe Curto is the guy that will help me.
Joe Curto is the guy that will help me.
Joe Curto is the guy that will help me.

To make the story short, with my car sitting in the garage in Boise, Idaho, Joe correctly diagnosed my problems in New York. Yes, he's that good. Google him....anything else could be a waste of time!

Rod Nichols

Come on Rod. We have to make him work for his meal.
Don't make it that easy

Dave-AFIK HS6 carbs always used .100" jets. The kit you received contains the wrong parts. Where did the kits come from? I have done the same conversion-HS6 carbs from a Volvo and it provided a lot on entertainment, but not much advantage over the ZS carbs. As you have probably discovered, the float bowls as used on the Volvo set at 30deg vs horizontal on the TR. The float bowl lids may have to be changed to ones from a Spitfire (AUD 2140) to cure a flooding problem. I am using BAG needles with the yellow 8oz springs, which are a little lean. Others may have different recommendations.
Blocking off the temp comps and bypass valves on the stock carbs can eliminate most of the frustrations.
As Rod suggested, Joe Curto is the recognized expert on all things SU.
Feel free to write me off list if you have other questions.
Berry Price
BTP Price

Started to type all that Berry mentioned in my first post but decided to wait to se if he's already talked to Joe.
So Dave- you have your answer. If you need Joe's contact info, just ask, or do the Google and you will find him and about a million post about him


The Burlen's kit for TR6 specify BAG needle. But if you look in archives sometimes it was mentioned they appears slightly rich. I am preparing my SU HS6 with BAD needle almost identical to BAG, but on the poor side for some steps.

Use that site to vizualise differences.


Jean G.
J. G. Catford

Jean-I find that the BAG needle is lean in the "cruise" area. I have a narrow band AF monitor and all the leds go out at about 2300 rpm and above. The plugs are also quite light in color.
BTP Price

What kind of #'s do the leds go out at?

Don-Probably about 3-4
BTP Price

Thank you Berry,

I will change to order BAG in such case as the infos were based only from what I read.

Jean G.
J. G. Catford

Jean-I would prefer a needle that shows 1-2 leds at cruise (2500-3000 rpm). I could go the needle polishing route, but that would probably lead to more frustration. Everything is a compromise and max performance would probably require 8 leds on, but the fuel consumption would be dismal. The buckeye tech article on using the AF monitor has a lot of good info.
BTP Price

OK Berry, I must not understand how this A/F meter works.
I was wondering what fuel% # the LEDS all go out at

Don-I think it was you who pointed out the narrow band AF monitor is a short cut to insanity and not to be taken too seriously. It is most accurate at stoich and less so as the mixture becomes leaner or richer. Nelson's chart shows that when all of the leds are off, the AF ratio is less than 18:1 and is too lean with misfiring. My engine seems quite happy and doesn't misfire, but the plugs are very light. Maybe there is a variation between sensors&monitors.
I removed the head last year and didn't find any damage to the pistons or valves.
BTP Price

18.1 Yikes that is pretty lean except at light throttle cruising on the Ohio turnpike. Might work there.

Is this with a NO2. Are you sure the O2 is working/ It could be in a bad location.What kind of Mv reading you getting from it?

Don-In my notes I have a reading of 880mv when 9 leds were lit. The single wire sensors are located in the bend of the down pipe-maybe 12" from the manifold flange.
The stock ZS carbs with B1AF needles would show 0-1 led at about 3K rpm.
Nelson's comment about suspecting a variation of +- 1 led comes to mind and not trying to read the data too seriously. A wide band monitor would be more usefull. Maybe E10 fuel is also a factor.
Berry-No NO2
BTP Price

That's pretty stickin rich

Sorry, NO2 is narrow Band O2

Sorry, I pondered over "NO2" and thought it might mean nitros oxide.
BTP Price

This thread was discussed between 08/02/2010 and 11/02/2010

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