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Tuning SU carbs?
- Thread starter Wombat
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64Spitfire
Senior Member
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take a look at the following links:
https://www.vtr.org/maintain/carbs.html and
https://www.team.net/www/morgan/tech/tuning.html
It's not hard to tune/set SU's, good luck
https://www.vtr.org/maintain/carbs.html and
https://www.team.net/www/morgan/tech/tuning.html
It's not hard to tune/set SU's, good luck
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Tuning of SU's is done by setting idle synchronization, idle mixture, which is set by the relative height of the needle jet, (adjustable over a limited range) the tension of the piston return springs, & the piston damper oil viscosity. Major fuel mixture changes are done by changing the profile of the tapered main needles. There are various charts on the net which show the relative diameters of the various available tapered needles. Usually the standard needle profile or one step richer or leaner will be in the ballpark.
One such chart can be found here. https://www.teglerizer.com/suneedledb/index.html SU plublishes a table of the various needle profiles.
The above references by 64 spit provide a comprehensive explanation of the subject.
D
One such chart can be found here. https://www.teglerizer.com/suneedledb/index.html SU plublishes a table of the various needle profiles.
The above references by 64 spit provide a comprehensive explanation of the subject.
D
Hello Wombat.
"They don't seem to have much in the way of adjustment screws!"
That is the beauty of the S.U. carburettor, the only mixture adjustment is the jet, with the needle providing the correct mixture through the range from idle to full speed. I'm assuming your TC is standard so needle selection is not an issue.
I run a MKI 1 2000 (albeit with a 2.5 injection engine) so if you have any queries with yours don't hesitate to post them. There is very little about this car on this board as I don't think Triumph exported them to America.
Alec
"They don't seem to have much in the way of adjustment screws!"
That is the beauty of the S.U. carburettor, the only mixture adjustment is the jet, with the needle providing the correct mixture through the range from idle to full speed. I'm assuming your TC is standard so needle selection is not an issue.
I run a MKI 1 2000 (albeit with a 2.5 injection engine) so if you have any queries with yours don't hesitate to post them. There is very little about this car on this board as I don't think Triumph exported them to America.
Alec
lesingepsycho
Jedi Warrior
Offline
That was great! I feel better about tuning the SU's on my moms car now. I vaguely recall trying to tinker with them in my childhood before we scrapped them and went to webers. Now I have such a better understanding of how these carbs work and therefore, much more confidence about getting them right! Cheers! /ubbthreads/images/graemlins/cheers.gif
JACK
JACK
lesingepsycho
Jedi Warrior
Offline
Well, I made it back to my mom's house today and got the SU's dialed in as best I could and they seem to be doing a really great job. I can see why a lot of racers still swear by them. Thanks to everyone for the info!
JACK
JACK