Slant 6- Idle and Running

I won't lie, you got me pretty excited there, the prospect of a single bolt fixing my problem... i jumped out of my seat! Unfortunately I don't have any vacuum pressure at that hole and it doesn't seem to go anywhere. I plugged it with a bolt anyway and unfortunately there was no change, purrs when cold, dies when warm. Which begs the question... am I meant to have vacuum pressure there? What circuit should it be connected to? I'm still not beyond thinking I have a vacuum issue.

I will be refreshing the carb this weekend hopefully and I think I will see my fix there. Slowswinger, I have that very same vacuum kit and will try to include some readings when I put the carb on.