Triumph Repair: TR6 with weber carbs, vacuum leaks, weber carbs

Question
Howard-

I'm trying to sort out the carbs, they're rebuilt 32/36 DGAVs. I've set the float bowls, primary throttle valves, and choke valves to the initial specifications for installation.  Now when I start the car it will idle for a couple of minutes, when it starts to warm up it doesn't want to idle and backfires through the carbs.  Any suggestions on what direction to go to sort this out?  Thanks for any help you can give.

Answer
Hi Dave,
Before you try to do anything with the carbs, you need to be sure the valve clearance is correct and the compression is good on all cylinders and the ignition timing is correct.
If all that is done (don't skip anything)check to see that the accelerator pump is working. All that takes is a look in the bore of the carb when you open the throttle quickly.

If everything is correct up to that point run this test.
Warm the engine up to the point that it has it's spitting mode and let it idle. Cup your hands over the intakes but allow plenty of air to enter the carbs. Now very slowly start to restrict the amount of air allowed in. If at any time as you slowly restrict the air supply, the engine smoothes out and/or speeds up a little, then you either have a vacuum leak or the carbs idle mixture screws are set too lean. When the mixture is set correct and there are no vacuum leaks, the RPM will just go down as you restrict the air and it will slowly get rough running.
Let me know.
Howard