Triumph Repair: stromberg adjustments, fab work, test lift

Question
I have a 1971 spitfire MK4 with a stromberg carb that I am trying to get through emissions...

I had high HC's and fixed it with a valve job and fixing a vacuum leak in the intake manifold.

But then the CO mix went up and failed me. I have tried to adjust the carb with the "fine idle adjust" (supposedly that is the co adjust) but it doesn't appear to do anything at all...

What can I do to get the co level down to pass the test?

I don't need a long term fix, I have a set of Mikuni carbs that I'm gonna be putting on soon but I need to finish some fab work b4 I do so and I just need the emissions done so I can title and register it.

Answer
Hi Nate,
You are correct that CO (when HC is correct) is mixture. Try to insert a long 3mm Allen wrench down into the top pot with the damper removed to see if it is one of the adjustable needle Stromberg carbs. If so turn the adjusting screw counter clockwise to lean the mixture. I can't tell you how far to turn it because it depends on how far the CO was out. Be sure the timing is correct before adjusting as incorrect timing will give you false symptoms when you try to adjust the carb. Be sure to put oil in the top when finished. Also, remove the four screws on the top pot and examine the diaphragm for holes or tares. Also look at the needle to see that it is not damaged. Check to see if your carb has a test lift pin just under the lip of the top pot on the left side. This is a test lift pin for mixture adjustment. When the engine is timed correctly and warmed up and the idle set correctly you can lift that pin and by the engine response adjust the mixture. The engine should drop off and sound like a two cylinder engine. It the engine speeds up and stays fast it is too rich and if it dies as soon as you lift the pin it is too lean.
The screw you were turning on the right side of the carb is a very fine trimmer and of no use for mixture adjustment.
Howard