It's only a waste of time if you don't understand what the writer was trying to tell you. I found what he was saying to be very simple and certainly not a farce;

Everything else taken in context I think his advice is pretty sound.

 

Well certainly as you open the throttle but when I held it steady at 2500 rpm (parked in the driveway) the vacuum settled at 21; at 3000, it settled at 22 or thereabouts. Are these numbers relevant to any vacuum gauge tuners?

 

Late comer here to this discussion. Ray it is entirely possible that your car was too far advanced previous to your current tune and the tuner got it closer to what it wants. It is also possible that he retarded the timing too much.
If we had timing numbers from a timing light to work with it may be easier to advise on what your timing should be, roughly. Without that information were kind of shooting in the dark.
If it doesn't detonate under WOT on a warmish to hot day then it's likely not too advanced.
If it doesn't run excessively hot on a warmish to hot day then it's likely it's not too retarded.
How is the throttle response? Nice and crisp. Problably good tune. Lazy response, timing might be a bit retarded or carb rich.
Mixture and timing work together. One is not exclusively in charge of the idle, cruise or WOT performance over the other. They have to work in concert to achieve optimum performance.
Short of you tuning the car yourself, I would take the tuner at his word unless you have symptoms of a timing or carb problem.

Yes, your vacuum will increase as you idle up the engine while parked. How high it gets is dependent on various factors, not the least of which is your cam, which won't be changed on a tune and has to be accommodated to match your timing and mixture tune.
I think Cardo is thinking about WOT operation or high load, large throttle deflections when he mentions the vacuum dropping as the throttle blades are opened.

 

Actually Lars has a Sun machine who has written technical specs on this subject. He is one of the best of the best ! I would reach out to him. He can curve your distributor up to the cam/motor specs if thats what you choose to do. Or ask for one of his papers for secrets...

 

Sorry folks but i have a vac gauge mounted right in front of me on my camaro and its calibrated to. Vacuum decreases as the throrrle opens. If your vac increases with rpm and throttle opening your on the wrong port. BTW reving to 3000rpm is not "idling up". U/he must not be on a port on the intake plenum but on one of the carb venturies (ported vac). As flow increases in the venturi yes vac will increase there (thats how the older aircraft get a vac source for vac opereated instruments). The principle is of absolute press becomes lower as fluid velocity in the pipe/venturi increases - static pressure decreases while dynamic pressure increases. Press less than atmospheric is what we call vacuum.

BTW i do understand that links writer is tuning with vac for idle circuit - but nothing for the mid range or WOT. Nothing. If u can find something that that author says then copy and post it. But u wont because it really was a farce to say so in the first place.

 

My 383 and 406 both idled with about 15 Hg of vacuum (no load) - but at cruise (steady RPM above idle), they could exceed 20 Hg. However, during the act of acceleration, vacuum clearly decreased. So higher (steady) RPMS does not always = lower vacuum. I think the OP is saying this. Sounds like a but of confusion whether the statements above are about higher RPM at cruise vs acceleration?

The total timing curve should take into all-around use (cruising vs WOT, for instance) for best results.

 

Cruising is a low load (high manifold vacuum) condition. At least that's what I was taught. Vacuum advance compliments this condition because engine rpm is low (offering little mechanical advance).

 

her good read for vacuum tuning.
http://www.gregsengine.com/using-a-vacuum-gauge.html

Note the section about exhaust restriction if you have decreasing vacuum to 3000 RPM.

Also notice the statement on vacuum indications, reduced initially then rebounds.

So quick or under load throttle defelctions will reduce idle initially then rebound as conditions are eaquilized.

A certain amount of vacuum at idle is associated with a certain idle speed. So if you are ldling at 500 rpm then you're gonna see lower vacuum vs idling at 800 rpm.
Is your idle rpm pretty low?