The vacuum tree is that little do-hicky on the firewall with all the vacuum lines running to it. Its on the driver's side of the engine bay and you'll see a large vacuum hose running from it down to the brake booster. Unplug one of the caps/hoses and put a vacuum gauge on it to read what kind of vacuum your motor is pulling. You can buy a pretty decent vacuum gauge at Sears for about $15 and its a good tool to have in the garage for diagnosing engine problems. With a stock engine you should be pulling at least 16 inches of vacuum at idle and probably more like 19 or 20 inches for a well running stock engine. Any type of aftermarket cam and your vacuum will start falling from there.
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Jeff Chambers
T/S #3
11.86 Seconds/113.8 MPH
Chambers Racing Team