From: John McKenzie on
Yvan wrote:

> Also, when this vaporizer was on my Audi it had the solenoid in the
> middle of it (as on the photo), and a another hose from the opposite
> side of the solenoid up to the mixer (some sort of vacuum control I was
> told).
>
> Now there is no solenoid, and no hose. Hole where hose was is left open.
>

I forgot to answer this sorry. This is the atmosphere side of the
convertor. Early versions simply needed it opened to the outside air. No
big deal. Then later on, they figured out that if the air cleaner
started to get clogged with dirt, it would start to suck harder on the
lpg and go richer and richer and waste fuel. So they then started to put
a hose from that part of the convertor to inside the air cleaner case,
so it wouldn't see true atmospheric pressure, but it'd see what actually
made it past the air filter. It's not a bad idea.

The next phase typically came about when cars started using EGO sensors,
then they'd put a stepper motor or a bleed of some sort on the back at
that hole, with one port usually going to atmosphere, and the other one
going to a place on the inlet manifold under the throttle plates that
would see higher vacuum. Then the stepper motor would open and close to
have more or less vac on the convertor diaphragm, and it would trim the
a/f ratio - whether this was for economy or emissions is debatable (in
terms of how much the driver should care about it).

Basically they've just taken it back to an earlier way of doing things.
There's nothing seriously wrong with the idea, but it can potentially
(once the current problems are sorted out) be a bit less fuel efficient
esp if the air filter is really dirty.


--
John McKenzie

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From: Yvan on
Nedavno John McKenzie piše:

>> > I will now (when the engine cools down) do the "one barell" lpg
>> > test, and report the result.
>>
>> I tried. I disconnected second barrel,
>
> just to be 100% clear - you disconnected the second barrel throttle
> linkage, wiring it so it might not be sucked open even a little it,
> AND you plugged the lpg/spud hose going to that barrel too?


I got up this morning thinking about what to try next, and I realized
that I made BIG MISTAKE. I disconnected and plugged lpg line to PRIMARY
barell!

That's why engine would run only with throttle nailed to the floor
at ~2500 rpm :-)

So I now disconnected lpg line to secondary barrel, and that made a
difference. I started on petrol by mistake, so I have to test starting
on lpg later, but it runs now on lpg after some 2-3 min when I changed
from petrol to lpg.

I did not disconnect second barrel throttle linkage, it's mechanical,
and quite complicated to disconnect. I just disconnected lpg line, and
drove the car taking care not to open second barrel. I also tried to
open it, car just decelerated (as expected, with no fuel line to it).


So it seems that Athol was right, perhaps secondary barrel spud acts as
an air bleed, and primary spud gets air/lpg mixture instead of pure
lpg.

But why is this problem only when engine is cold? More concentrated
(dense, I can not find the right word) lpg when cold? So mixture is
reacher?


But why would that change with a mixer plate? I would again have the
same setup. Vaporizer, Y piece with two main flow mixture control
screws, two hoses and mixer plate. So again I have connection from
primary to secondary barrel mixer ring trough Y piece. Again can
secondary barrel mixer ring act as an air bleed. Or not, and why?


--
___ ____
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/ / \/ /\ \ ** Registered Linux user #291606 **
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From: Yvan on
Nedavno John McKenzie piše:

>> Now there is no solenoid, and no hose. Hole where hose was is left
>> open.

I made mistake here, solenoid is present, I think it just cuts off lpg
at the same time as solenoid on lpg liquid line (at least it clicks at
the same time)

> I forgot to answer this sorry. This is the atmosphere side of the
> convertor. Early versions simply needed it opened to the outside air.
> No big deal. Then later on, they figured out that if the air cleaner
> started to get clogged with dirt, it would start to suck harder on the
> lpg and go richer and richer and waste fuel. So they then started to
> put a hose from that part of the convertor to inside the air cleaner
> case, so it wouldn't see true atmospheric pressure, but it'd see what
> actually made it past the air filter. It's not a bad idea.
>
> Basically they've just taken it back to an earlier way of doing
> things. There's nothing seriously wrong with the idea, but it can
> potentially (once the current problems are sorted out) be a bit less
> fuel efficient esp if the air filter is really dirty.

Thank you for the explanation, I will connect to the inside of air
cleaner if I sort current problems.

--
___ ____
/__/ / \ ** Registrovani korisnik Linuksa #291606 **
/ / \/ /\ \ ** Registered Linux user #291606 **
/__/\____/--\__\ ** http://counter.li.org/ **
From: Noddy on

"John McKenzie" <jmac_melbourne(a)bigpond.com> wrote in message
news:47491EAE.36FD(a)bigpond.com...

> the thing to be mindful here - as there is normally locally some
> criticism of that combo - it's not the amos ring thats the big problem -
> it's that the adm weber is too small for a reasonable breathing 4 litre
> engine.

It is, and that's a good point.

--
Regards,
Noddy.


From: Yvan on
Nedavno Athol piše:

>> But why is this problem only when engine is cold? More concentrated
>> (dense, I can not find the right word) lpg when cold? So mixture is
>> reacher?
>
> As Noddy mentioned, the choke plate may also be contributing. The
> choke butterfly on the top of the primary barrel generates suction due
> to its presence. This will increase the strength of the vacuum signal
> at the spud and exacerbate the secondary air bleed effect.

Aha, I didn't think of that.

> There are other possibilities, but I'd lean towards Noddy's suggestion
> of putting a choke cable in so that you can manually close the choke
> butterfly on petrol and leave it open on gas as the most likely
> solution to that part of your problem.

And if I somehow fit mixer plate I would not have this problem. Right?

>> But why would that change with a mixer plate? I would again have the
>> same setup. Vaporizer, Y piece with two main flow mixture control
>> screws, two hoses and mixer plate. So again I have connection from
>> primary to secondary barrel mixer ring trough Y piece. Again can
>> secondary barrel mixer ring act as an air bleed. Or not, and why?
>
> If you have a plate above the carby, it is a single ring feeding both
> the primary and secondary. The vapour line from the convertor would
> usually go through a single adjuster, then to the Y-piece, which feeds
> to both sides of the ring. In effect, the mixer plate sees only one
> airflow consisting of the flow to the primary and secondary before the
> air splits to the two barrels.
>
> It is possible to have a single feed line to the ring, it's just an
> easier and cheaper setup to have feeds on both sides and avoid having
> a concentric distribution ring outside the venturi.


It's not single ring. This is the photo of the original mixer plate for
Weber 32 ADF:

http://www.ptt.yu/korisnici/i/v/ivica/lpg/Weber32ADFmixer.jpeg


--
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