Nothing important here. Just something I wonder about from time-to-time.

Why are the AAV hoses so large? That is, large diameter?

Whereas the opening in the AAV that air passes through is about the size of the tip of my little finger?

What's at play here? The thermo-dynamics of air flow compounded by the coefficients of linear expansion...to offset the inevitable turbo-encabulator effect?

Cheers
DD

 

Ah Yep.

Some scientific angle of the dangle mumbo for sure.

Or, they had this stuff left over from something else, and use up what they had.

Since I dont run them, or the balance pipe, nothing to look at, and ponder.

 

I've eliminated my AAV as well.....which is why the question came to mind again.

Just a curiosity thing.

I'm working on an alternate idle speed adjustment scheme. And, possibly, incorporation of an AAV from a different car. I say 'possibly' because, although it'll be an interesting project, I don't view the AAV function as essential and have other things I'd rather spend the time on right now.

Cheers
DD

 

Greg rotated the piston 180deg, and sealed down the intake carefully with JB Weld.

This disabled the AAV as a cold start aid, but retained the idle adjuster bolt and the air bleed passage.

Probably a sound conversion for the "average" V12 owner.

 

That is true, Doug. I got fed upwith the AAV sticking every so often, so retained the part that is the idle speed adjuster, and blocked off the extra air passage. Then I fitted a T shaped hose (from the guys at Viper Performancein the UK) to replace the normal B bank crosspipe rubber hose. Into the leg of the T is fitted a genuine Jaguar solenoid air valve as was fitted to the 3.6 litre cars for cold start purposes. See 8 in the diagram link here: https://www.jaguarclassicparts.com/u...alve-3-6-litre
Cabin switch for the solenoid. Works wonderfully well in cold weather; I switch it off after about 800 yards. A few diagrams and snaps attached.
Greg

 

I have a small question, it is about AAV, too.
After replacing rotor :
https://www.jaguarforums.com/forum/x...lm9624-190618/
I connected hose for distributor vacuum :



But I have no vacuum there (11). Only when I cover the hole for AAV in filter case, then I have here vacuum, which is equal to vacuum in inlet manifold. It is clear. All air for idling engine is going through hoses (13).
But when I open this hole, vacuum is again zero. It does not depend on RPM. It is normal (I think not) ? Or I have a mistake somewhere, or I have forgotten something ?
Thanks Roman

 

This is NORMAL.

That vent hose is actually a "draft hose" in the Intake hose of the AAV. There is NO vac in that system at all. The draft is all that is needed to vent the distributor.

It has been a very confusing interpretation of words for as long as I can remember.

 

As I understand it....

The filter/inlet is at atmospheric pressure. Incoming air rushes past the vent hose connection at the AAV creating a lower pressure....sort of like a venturi effect, I reckon. This pressure differential 'pulls' a small amount of air through the distributor vent system. So, no, you won't feel 'vacuum' in the sense you're thinking of.

The same principle (whatever it is correctly called) is used on your climate control system. The tubing for you cabin temperature sensor is exposed to cabin air at one end and is connected to the main air flow ducting at the other. When air blows thru the main ducting it pulls air through the temp sensor tube to create a small amount of air movement across the sensor.

Cheers
DD

 

Thanks, Grant. I was still typing while you were hitting 'submit'.

"Draft hose' is a perfect description that I was struggling to find

Cheers
DD

 

Thanks.

Draft hose is clear explanation. And I'm calm again