Triumph Repair: SU CARB, triumph spitfire 1500, float chamber

Question
HI PETE HERE
           HAVE A TRIUMPH SPITFIRE 1500/1977 MY TROUBLE IS A FUEL PROBLEM.CAR STARTS FINE,WITH THE AIR FILLTER OFF YOU CAN SEE THE FUEL ENTERING THE CHAMBER,WHEN YOU OPEN THE THROTTEL TO 3.5 REVS THE FUEL CUTS OUT ,NEW FUEL PUMP/FUEL LINE CLEAR/TIMMING FINE/IGN FINE. CANT WORK IT OUT

Answer
Pete,

SU or Stromberg?  Not that it makes a huge difference... but it changes some of the troubleshooting.

I take it that with the car stationary you're having problems revving past 3500 rpm?

What does the car do when you try to rev past 3500?  Stutter?  Stumble?  Shut off completely?

If you're positive the ignition timing (dynamic) is correct then it's possible the fuel level in the float chamber is set too low.  Or that there's a fuel delivery problem.

Have you tried using the choke to see if changing the mixture has an effect when you rev it?

If it is an SU is it an HS4?  And how are the fuel vapor vents hooked up?


Cheers,

Jim