Pull the tin cover off the bottom and expose the fly wheel. apply black paint to the "BB" and wipe it off. It will stay in the stamping. Apply white paint to the area around it for contrast. Put the tin back on, lay the timing light on the starter and you will see it just fine. A bit of paint on the pointer can help too. Set the idle at 450-500 RPM then try to set the timing. There is a mechanical advance in the dizzy, and it will add to the total advance at a "high" idle speed. If things are badly out of adjustment you may need to repeat the timing after other things are adjusted. The vacuum gauge is rated in inches of mercury not pounds by the way. Still, if you have only 12 inches of vacuum there are other issues that need attention. Any tight valve will leak enough to drop the vacuum. Any leak at the manifold will cause it to drop as well. But to get a good reading it must idle. Adjust the valves a bit loose. Add .005 to the factory spec and don't worry about the clicking. You can fix that later and it won't hurt anything but your nerves.On all of the manifolds I have seen, the fitting is on the driver side out board and below the carb insulator. Pull the line to the wipers and put the vacuum gauge on there. leave the line on the vacuum advance until it will idle.Turn the idle down as much as you can. open the choke as much as you can. If the mixture screw is in too far it will be too lean, back it out 1/2 turn and watch the vacuum gauge. If it gets better turn it out another 1/2 turn, if the idle goes up open the choke some more. If it does not, try setting the timing again. A little adjustment can make a big change at the vacuum gauge. If the idle goes up, open the choke some more and try the mixture screw again. Turn the idle down and see what you get. If all this makes no change you may have to pull the carb. You might have a loose manifold. There can be some issues with the point gap as well. One thing at a time.
