I put my finger over the hose venting the distributor, and
it doesn’t seem to be flowing much, if any. I really didn’t
feel it sucking at all. I know this is very subjective but
‘‘how much’’ should it flow? I checked it at idle, 600rpm,
fully warmed up.–
Mike B
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
// please trim quoted text to context only
Mike,
Very, very low. The driving pressure drop is just that between atmospheric
and the pressure downstream of the LH intake filter, in the standard
plumbing.
Ed Sowell
'76 XJ-S coupe, red
http://www.efsowell.us/ed/myJag.html
I put my finger over the hose venting the distributor, and
it doesn’t seem to be flowing much, if any. I really didn’t
feel it sucking at all. I know this is very subjective but
‘‘how much’’ should it flow? I checked it at idle, 600rpm,
fully warmed up.Mike B
// please trim quoted text to context only
Hi Mike,
As Ed has already indicated, even if the tube is intact to the AAV
intake hose, the pressure drop is small, probably less than 1 in. Hg.
It is NOT manifold vacuum, which would suck in the cap gasket (a reason
to disconnect the vent hose from the top of the cap if you are testing
the AAV by plugging the intake on the left air cleaner back plate). It
is just the pressure drop that the air cleaner element provides where
the AAV is drawing in air.
However, I would check the plastic T fitting on the inboard side of the
AAV hose, to make sure that has not broken from age/heat, leaving you
with absolutely NO pressure drop at all and the vent suction hose
hanging loose at the AAV hose.
George Balthrop, Clifton, VA USA
85 & 89 XJ-S Coupes; 89 XJ40 VDP-----Original Message-----
From: Mike B stimpsonjc@hotmail.com
I put my finger over the hose venting the distributor, and
it doesn’t seem to be flowing much, if any. I really didn’t
feel it sucking at all. I know this is very subjective but
‘‘how much’’ should it flow? I checked it at idle, 600rpm,
fully warmed up.
// please trim quoted text to context only
Yes, I guess it would since higher RPM means higher air flow and therefore
higher velocity through the filter. That would mean higher pressure drop.
Never tried it though. Let us know what you find.
Ed Sowell
'76 XJ-S coupe, red
http://www.efsowell.us/ed/myJag.html
Very, very low. The driving pressure drop is just that between
atmospheric
and the pressure downstream of the LH intake filter, in the standard
plumbing.
// please trim quoted text to context only
In reply to a message from Ed Sowell sent Sat 23 Aug 2008:
I tried it at higher rpm and still didn’t feel any flow.
Everything looks to be fine - I can trace the vent hose to a
plastic elbow that connects to the AAV ‘‘sucking pipe’’. I
also tried this with my fingers over the AAV inlet in the
airbox (where there IS suction of course), still no suction
thru the vent scheme. I guess the elbow is somehow plugged
up? Weird.–
Mike B
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
// please trim quoted text to context only
Mike,
I guess we don’t have a good point of reference. That is, should one be able
to feel suction with a fingertip over a port downstream of the filter? I
don’t know. My situation is a little bit different since my car didn’t have
it in the first place. I simply got the vented cap, drilled a hole through
the back of the filter housing and hooked it to one of the posts on the cap.
The other cap port is connected through a small filter to ambient air. I
assume that the Jaguar engineers somehow determined that this would provide
enough venting for the distributor. It doesn’t have to be much.
Ed Sowell
'76 XJ-S coupe, red
http://www.efsowell.us/ed/myJag.html
I tried it at higher rpm and still didn’t feel any flow.
Everything looks to be fine - I can trace the vent hose to a
plastic elbow that connects to the AAV ‘‘sucking pipe’’. I
also tried this with my fingers over the AAV inlet in the
airbox (where there IS suction of course), still no suction
thru the vent scheme. I guess the elbow is somehow plugged
up? Weird.Mike B
// please trim quoted text to context only
In reply to a message from Ed Sowell sent Sat 23 Aug 2008:
Ok, I narrowed it down a little… I can get air to flow
thru the hose (in either direction) between the distributor
and the AAV pipe. I can get air to flow through the little
filter and it’s hose. The distributor itself however is
quite restrictive. I’ve had the cap off twice, had the
whole thing apart, and don’t recall seeing anything in there
that would restrict flow, but I guess I will take another
look. I’ll report back if my findings are at least mildly
amusing.
Mike–
Mike B
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
// please trim quoted text to context only