Not really. A major leak will reduce the vacuum a little, but there can be other reasons for this (cam timing out being one example).
Leaks elsewhere are where you need the length of heater hose and a Mk.1 earhole. 
Fair enough mate. Sorry to be stupid here though but with this tool (vac gauge) is there nowhere i can hook it up to check for vacuum leaks in the intake manifold which would give the same (if not much more precise results) as the carb cleaner round hoses in the engine bay? if so i'm not going to spend the dosh and as you say, ill just revert to the heater hose. 
The only way you could test vacuum in the 'rest' of the intake is with the engine running - the vacuum measured being a result of the engine attempting to pump air into the cylinders past the restrictions of air filter, pipework, throttle butterflies etc (you'd find negligible vacuum before the throttle butterflies and much more after, for example, at all but full throttle).. what that means is you can hook up a vac gauge and see 'vacuum' but it's hard to say what it should read as every engine is different and 'right' will vary hugely depending on ambient conditions, engine condition, how the ECU is maintaining idle etc etc.
When you hook the vac gauge up where Kevin indicated you will, with the engine running, see the same thing - a varying vacuum. The important test, then, is after you stop the engine. As there's a one-way valve in the feed to the vacuum system and a vacuum reservoir you should find that when you switch the engine off, vacuum is maintained there - it shouldn't escape anywhere thanks to the valve and sealed nature of the system. If it does then you've found (somewhere) a vacuum leak in the pipework or vacuum reservoir that exist
after the one-way valve. In this case it's not so much how much vacuum you see that is important but the fact that it doesn't (quickly) reduce to atmospheric pressure.
If you're looking for vacuum leaks in the rest of the intake system - e.g. inlet manifold to sandwich O-rings or IACV gasket on a non-DBW - then your options are (IMHO, others may disagree):
1) Mk.1 ear with a pipe and the engine running, as Kevin says - a vacuum leak will sound like a squeal through that, like a stuck pig.
2) Plug the air intake somewhere after any fresh air vent for the PCV system and fill it with smoke, look for the smoke escaping. Can be problematic on modern cars as there are so many vacuum and ventilation feeds and the PCV system is relatively complex that you can end up worrying about nothing as you fill the crank case with smoke..
3) Plug the air intake at the throttle bodies and pressurise the intake (slightly!) to, say, 4-5psi with a foot pump. Now use the Mk.1 ear again but this time you can do it with the engine off and listen for a hiss.
3) is more effective on a turbocharged car where the intake system is
designed to see positive pressure as you can usually test from the turbo or even the MAF downstream, rather than just the throttle bodies.
Incidentally, I'd suggest thinking of the system as two separate parts when you're talking about looking for vacuum leaks..
There's the accessory vacuum system - this is the vacuum feed from the inlet manifold that goes to the brake master cylinder and services that along with all the other vacuum operated valves (multirams, heater bypass, heater control flaps, etc) - and there is the rest of the intake. On the Omega, the rest of the intake can be considered a vacuum system (as you are thinking of it), but on a turbocharged car that system will see positive pressure as well; it's not strictly a vacuum system.
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Topic: Finding Vacuum Leaks....with a cigar (Read 2503 times)