The Triumph Dolomite Club - Discussion Forum

Dollyby 2 wrote:Hi Jonners,my carbs are non waxstat,the number on both floats is Fzx1258f, what does this denote to?.I am not very familiar with su's,the choke is disconnected and both sets of clamps are loose also,there is some play in the spindles.I will check float levels when I get a minute or three,I presume this means taking the lid off and a visual.Would centering the jet/needle help? thanks so much for your help.Regards, Myles.

FZX1258 is a HS4 fitted to a Triumph Dolomite 1500 from 1976 to 1977, the suffix 'F' and 'R' are cunningly, front and rear!

http://sucarb.co.uk/pair-of-hs4-carbure ... 76-77.html

On SU's fitted to our generation of cars the centralising of the jet is not necessary or possible
as the needle is sprung biased to one side.

As you have non waxtstat jets its highly likely the float level that is causing rich mixture, or a badly worn jet.
Check for dirt in the float valves or wear on the needle that would let them leak.

As Alan said its also worth a check that the overflow vent isn't blocked.

Jonners

Hi all,Jonners I checked float levels and rear one is 5mm higher than front(5mm more petrol in chamber) so apparently there is a problem there.Alan, the breathers onthe overflows are fine as is the choke mechanism,I have some spare carbs in various stages of disrepair so will see what I
can do with them,Jonner, I checked one of the jets and see what you mean, it is essentially selfcentering,will give an update when I can,thanks so much again,Myles.

Hi all.a brief update,both carbs were removed and stripped, and cleaned,one carb body was
replaced as it had badly worn spindles and bushe.I put some o rings on the spindles where they protrude from carb body,although
there is still wear on the spindles they don't seem to be taking air.I also put some tie wraps on breather tubes.I then went through the normal procedure for tuning su's and the
engine is running much better, just some fine tuning now so thank you all for all your help, Myles.