Does anyone feel like a brief disertation on engine vaccuum?
I know the trans ues it as does the carb&brake booster.
(am also baffled by the PCV valve going to a vaccum source(?) that makes NO sence)
Is there somewhere i can find out exactly where sall my vac. lines need to be on my 67 Goat?
thanks as always
I'll take a shot at it. Engine vacuum / manifold vacuum is generated by the pistons of a running engine "sucking" against a restriction, in this case, the throttle plates of a closed/partially closed carburetor. That's why at "full throttle" when the restriction of the throttle plates is removed, vacuum drops to zero (or very close to it) - the engine is being allowed to "eat" all the air it wants. Vacuum is important for proper operation of the carburetor idle and part throttle circuits. When air-flow through the main carb venturis is very low (idle or part throttle) the carb allows engine vacuum to "suck" fuel through these passages. At wide open throttle (WOT) when the vacuum goes away, the idle and part throttle circuits in the carb stop working becuase there's not enough vacuum to activate them. Instead, now that the air flow through the carb is high, the main venturis come "on line" and begin operating to supply fuel (metered by the primary, secondary, and power circuits). The purpose of the accelerator pump in the carb is to supply a shot of fuel to help carry the engine through that transition point, when the idle/part throttle circuits are shutting down and the "main" circuits are coming on.
There are usually two types of manifold vacuum "connections" available on a carb, ported and non-ported. A non-ported connection "sees" real manifold vacuum from below the throttle plates. A ported source is located above the throttle plates in the carb, so it won't "see" full manifold vacuum until the throttle plates are open somewhat. Typically, the vacuum advance on the distributor is connected to a "ported" source and everything else uses a non-ported source. "Lots of stuff" has used engine vacuum as a source of "free" energy over the years. Back in the days of 6-volt electrical systems it was common to use it to power windshield wipers. That's why they'd stop working whenever you stepped on the throttle.
PCV, "Positive Crankcase Ventilation" is one of the earliest forms of "pollution control". Before PCV engines generally just used an open tube that vented the crankcase to the atmosphere. Problem was, on an engine with very worn rings/cylinders that generated lots of "blow by", all that smoke just vented. Crankcases do need to be vented, otherwise the "back sides" of the pistons are going to build pressure and tend to do things like pushing out gaskets and creating leaks, not to mention working against the power the engine is trying to make. Along comes PCV. The reason it's connected to engine vacuum is so that the vacuum will "suck" this pressure/gasses out of the crank case and feed it (along with fuel/air) into the cylinders to be "burned" and passed out with the rest of the exhaust. The reason you need a valve is to prevent air/fuel mixture from flowing the other way INTO the crank case at WOT where the heat and pressure can ignite it, causing a "crankcase backfire" which -really- does a number on gaskets and seals, besides being dangerous. The PCV valve acts as a one-way valve that allows crank case pressure and gasses out without allowing air/fuel in.
As far as how to route/connect all the vacuum hoses, from about 67 and up it got more and more complicated as emissions controls were introduced. I know on my 69 there was a vacuum valve mounted to the water crossover on the intake that "mixed" a combination of vacuum advance, vacuum retard, ported and non-ported vacuum all depending on engine temp. The best reference for your car would probably be a copy of the factory shop manual.
Hope that helped...