Triumph Repair: 1977 spitfire fuel problem ?, bright sunny day, float chamber

Question
Howard, I thought I would follow up with the final outcome of the fuel problem.  As you recall I reinstalled the head after a valve job and the engine would not run at a high RPM. It would idle and rev nicely when I pumped the accelerator but not run at a constant high rpm. Valve clearance, timing, cyl. compression, fuel pressure, all checked out. This afternoon I took the top and bottom of the carb off AGAIN and blew out jets etc with comp. air again and reassembled. The differance this time is I used a new float chamber gasket. The eng. started and ran just fine.          Thier was never any fuel leaking from the float chamber but is it possible that it was sucking air during periods of high demand thus causing the eng to die when continuous high rpm was demanded.  As it stands now the engige and car are running well. It does miss every once and a while in 4th gear at 40 to 50 mph. Don't know if this is common or still an issue. I would appreciate your comments on the gasket replacement and the high speed cough. Thanks again, Pat

Answer
Pat, the float chamber gasket can't suck air as there is no vacuum there. If there was vacuum there the engine would not run at all. Blowing the jet out may have forced trash out or water but the float chamber gasket had nothing to do with it.

If an engine is running good except a single miss at times you need to put a timing light on the coil wire not a plug wire like setting the timing. Tape the trigger down and place the timing light under a wiper arm and drive the car to get the miss. The timing light flash will look like a steady light but any miss fire will show up as a blink of that steady light. If it is a bright sunny day when testing, you may have to tape a piece of cardboard over the light to shade it so you can watch it while driving.

It is very unusual to have fuel to cause a single miss at any speed. A fuel problem will be longer and more constant.

Howard