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TR6 HD6 carbs on TR6?

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Not on a TR6 but I have HD6 on my TR3. Had to buy lean needles but I got more power from the engine. Another guy in our club that also has a TR3, remarked on how much more power my car has. It can keep up with Healeys. I did install a cable to work the throttle since the controls are different. While the 4 vs 6 cylinder Triumph engines are different, the HP that comes out is not that far apart.
 
Jerry said:
Not on a TR6 but I have HD6 on my TR3. Had to buy lean needles but I got more power from the engine. Another guy in our club that also has a TR3, remarked on how much more power my car has. It can keep up with Healeys. I did install a cable to work the throttle since the controls are different. While the 4 vs 6 cylinder Triumph engines are different, the HP that comes out is not that far apart.
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Jerry - thank you for the input. Good to hear from someone who's actually done it. Can you post a picture?

Was interested in this, as I already own two HD6s left over after I upgraded my Healey to HD8s and was thinking of rebuilding them and installing on the TR6 as a fun project. Joe Curto thought it was a bad idea as by the time I bought vertical float bowls and had him rebuild them, I'd be in the $700+ range - half the price of Moss' new HS6 kit. But I can rebuild them for a lot less than $700.

Not sure why they'd put out any more power as both designs have the same 1-3/4" bore. Are you sure your car doesn't have other advantages vs your buddy's? Apples-to-apples and all that rot.

The main advantage is HD-type carbs are easier to tune, as the screwdriver-accessible mixture screw is accessed from the top with the air cleaners in place.

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My understanding is the HD6 have an accelerator pump that may be the difference. My engine does have some head work that would help also.
 
Jerry said:
My understanding is the HD6 have an accelerator pump that may be the difference. My engine does have some head work that would help also.
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SUs don't use accelerator pumps. The accelerator function is a combination of the strength of the piston spring and the weight of the damper oil. This is one of the reasons they aren't quite as good as Webers, which have an actual accelerator pump.
 
I put older Zenith Strombergs from a TR4 or 4A on my TR250. They are much simpler carbs, not really any different than the same era SU other than the rubber diaphragm to seal in the vacuum. Not suggesting they are better than HD6s, but another option. They are not stock of course, but they do look closer to the stock item than SUs.
 
glemon said:
I put older Zenith Strombergs from a TR4 or 4A on my TR250. They are much simpler carbs, not really any different than the same era SU other than the rubber diaphragm to seal in the vacuum. Not suggesting they are better than HD6s, but another option. They are not stock of course, but they do look closer to the stock item than SUs.
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I used the same carbs on my TR6 without any problems. The only downside was not having ports for the crankcase vent tubes and also having float chambers that required removing the carbs to deal with a stuck/clogged needle valve. I switched SU HS6 carbs that had the vent tubes and have been satisfied. The SUs did require modifying a stock needle profile to suit the engine.
Berry
 
titanic said:
...The SUs did require modifying a stock needle profile to suit the engine.
Berry
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Berry - modifying needle profiles is non-trivial. Are you running O2 meters?

I had planned on starting with the Healey lean needle on my HD6s, but might be better off using whatever needle the Moss HS6 kit comes with.
 
Just an idle question - why would you bother? The two carbs are very similar - just the rubber skirt on the Strombergs so Triumph wouldn't have to pay royalties to SU.
 
Steve-I did use an AF meter, but it was a long time ago and the only thing available was the narrow band type, which was better than nothing, but not much. Later, a good Samaritan (Dale O) who had a wide band AF meter, and had similar engine mods, shared his experience He recommended a KN needle with 4-1/2 oz red springs for "everyday use". He re-profiled it for a "performance" needle If you are interested, PM me and I will give you the profile.
I think Moss recommends BAG or BAE (depending on mods) with the 8oz yellow springs, i found them to be too lean.
If you are considering engine upgrades for performance, an increase in the CR to 9.5, recurving the dist., and then maybe an upgrade in cam, gives the most bang for the buck.
Berry
 
pdplot said:
Just an idle question - why would you bother? The two carbs are very similar - just the rubber skirt on the Strombergs so Triumph wouldn't have to pay royalties to SU.
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it was about smog. The SUs couldn't cut it.

Why would I bother? Good question. Maybe I won't - having fun thinking about it. :fat:
 
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