If it's steady, that means thumbs up! You can use the gauge to set your idle mixture (once the truck is hot), you just want the highest vacuum reading. You know the drill by now, adjust the idle speed, adjust the mixture, adjust the idle speed, adjust the mixture...Blah blah blah. I don't have a tach, so I just use the shop manual method of setting the idle, high gear on flat ground idle is about 7 mph or whatever. Then adjust he mixture for a smooth idle, just like the manual says.
The engine needs to be hot anyway, so you might as well go for a road test to do this stuff. All you need is a screw driver, and a wrench to fit the octane selector. I just keep these in the glove box.
Once you are running down the road, you set the timing on the road test, using the "octane selector". I like to get the truck hot, and find a local hill where you can do the test in high gear, you slow down, and then tromp on the throttle, if you here pinging (sounds just like glass coke bottles), then you retard the timing a couple of degrees, and try the test again. Or, you keep testing, and advancing the timing until you have to back it off. You need to do this every time you tune the truck, and set the points. Changing the points, or gap changes the timing. By doing this, you get more efficient engine operation, which means both more power, and economy. I guess you don't have to do this step, allot of people don't, but I'm for all the efficiency I can get, as I drive my bus every day. By doing the road test, you can also get a better understanding of how the point gap effects the timing of the engine, and how that can be important.
All this junk is in the shop manual, and they probably do a better job of 'esplainin' it.
