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Hiya all out there in Triumph land

just finished fitting 1 1/4 twin Su carbs on my 1200 convertible, along with a
4 into 1 manifold + new stainless exhaust ( twin back box ) couldnt afford the
Vitesse, so working my way there slowly (LOL)

Anyway car starts fine, revs great and drives well until you get up in the high gears i.e speedo showing 60+ and it just feels that car is being held back, ( strangling herself ,if that makes sense)you can feel just one more adjustment some where and she would free up and rev right out .

Have adjusted the timing to 17 degrees, or should i say a mate of mine has, so i hope that makes sense to , do i need to do something here ?

( to be honest its the best the car has been since i bought her nearly 3 years ago, just the one prob )

I have tried weaking the mixture which makes it worse and tried riching up the mixture, being rich makes her better, but still doesnt feel right

one thing i have noticed is that advance / retard vaccum isint working and would definatly say it hasnt since i had the car, but never had this feeling of the car holding back. though i will say she still does according to the speedo 70, but like i say something doesnt feel right

Any advice would be greatfully appreciated

all the best

Iain

Hi Iain,
Tuning really isn't my area of expertise, but you've made no mention of fitting appropriate needles to suit the manifold and air filters of choice. It sounds as though the engine is running out of breath, the needles are probably leaning out the mixture at the top end as they have the wrong profile. I'm sure someone else will be able to tell you what needles you should be using.
Cheers,
Bill.

I agree that you need to have the correct needles, whatever they are. If you have the wrong profile you'll never be able to get the right mixture throughout the engine range by jet adjustment.

If the centrifugal advance is not working, then again you'll never get the proper performance. (You can probably live without the vacuum unit, but the centrifugal advance is a crucial part of the engine set up).

HI
I too have a 1200cc engine with twin 1 1/4s and pancake filters, 4 to 2 to 1 exhaust and twin back box, but mine hasn,t been run yet (well I DO need to fit some of the parts!) I am assuming that my needles will need changing, and wondered if anyone had any suggestions on what they use (I know a rolling road is best for this but funds do not allow)

Thanks
Tim

Hi Tim,
If you don't get any luck here, try posting on the Yahoo Group for Heralds:
http://autos.groups.yahoo.com/group/triumph_herald...
If you're not already a member then you ought to be, it's almost certainly the world's biggest collective of Herald knowledge,
Cheers,
Bill.

Section : Carburettors

Twin Su

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