OMVL Vapouriser query
Autolycus
engine, Mallory twin point distributor, Lucas coil, Magnecor HT leads.
Engine said to have been overhauled (bearings, rings, new 3.9 efi
camshaft, etc within the last 10k.
The LPG system: a Chris Perfect Iwema kit, installed in the last couple
of years by the previous owner. Twin underslung tanks (replacement
in-wing petrol tank), OMVL R90/E-D8 vapouriser, ecomax, Iwema? mixers.
The problem: general poor running. Down on power throughout rev range,
occasional hesitation (almost cutting out), irregular idling, stopping
on return to idle at, e.g. junctions.
Ignition timing is OK. Petrol running is poor, too, but last owner a)
said he hadn't used petrol since he installed lpg, but b) had gone to
the trouble of installing an extra in-tank petrol pump because he
suspected the original pump couldn't cope with the extra few feet of
suction side pipe to the new tank. Hmmm.
Since it starts OK on gas, I was minded to concentrate on getting that
right first, so went through the setting up instructions supplied.
First question: what does the smaller hex head brass adjuster next to
the idle mixture adjuster do? The instructions say it should normally
be screwed right in, or up to 1/2 turn open, but mine was about one turn
open.
I can't find any reference to diaphragm tension adjustment, though this
seems to be mentioned frequently as part of normal tuning. Does the
OMVL have such an adjustment?
There was some oily gunge in the carb elbows, downstream of the mixer.
Could this be carry-over of heavy ends, and if so is there a drain plug
on the OMVL I should check?
I'm about to start going through all the engine basics (compression,
plug condition, etc) but any suggestions as to subsequent procedure
would be much appreciated. I've got an MoT booked for tomorrow, but at
the moment it's looking unlikely I'll get it there, let alone have it in
a fit condition for an emissions test.
Perhaps I should have bought the tdi after all...
--
Kevin Poole
***********Remove lid from email address before replying
******************
Autolycus
Following up my own earlier post about running problems with the Range
Rover, I think I have found the main problem; a duff condenser on the
new-looking Mallory distributor. It now starts and runs, which earlier
in the day it barely would.
Following the setup instructions, the main flow valve (on the Y-piece to
the mixers) is now virtually fully open, and it's idling OK with the
smaller brass screw fully in and the larger one a bit further out than
the suggested initial setting. I'd still like to know what the smaller
one does. The ecomax is roughly mid-travel.
I also found a capped-off alternative outlet to the mixer, at the
bottom, so presumably this serves as the drain, though nothing much came
out when I pulled the rubber cap off.
So tomorrow's MoT is on again, though I haven't been able to check the
idle CO and HC because my wretched gas analyser isn't working.
Tdi put on hold ;-)
Stewart Hargrave
18:21:02 +0100 the life form we call "Autolycus"
<lidcof...@ntlworld.com> tried to communicate the following message
to us:
>
>Following up my own earlier post about running problems with the Range
>Rover, I think I have found the main problem; a duff condenser on the
>new-looking Mallory distributor. It now starts and runs, which earlier
>in the day it barely would.
This seems quite likely - it is harder for a spark to jump a gap in a
mixture of LPG than of petrol, and if your ignition system is not in
first class condition the spark will fail or try to jump a gap
elsewhere. This can lead to bad running and backfires.
--
Stewart Hargrave
Never wear a hat that has more character than you - Utah Philips
Austin Shackles
<lidcof...@ntlworld.com> enlightened us thusly:
>
>Following up my own earlier post about running problems with the Range
>Rover, I think I have found the main problem; a duff condenser on the
>new-looking Mallory distributor. It now starts and runs, which earlier
>in the day it barely would.
okay...you asked:
OMVL has 2 adjustments - the 8mm head screw is a fixed idle bleed, the 10mm
head screw with the spring on it is diaphragm tension and affects mixture at
all speeds.
put in on a *good* analyser, run it at about 3000 rpm with the vacuum pipe
to the ecomax disconnected and plugged.
adjust diaphragm tension and/or max. flow adjuster (in the gas outlet pipe)
to get about 1% CO. My landy currently has the max flow quite wide open,
but you may get better answers with it about half-way in - it depends on
what air cleaner element you have etc.
drop it back to idle, and see what the idle mixture looks like, bearing in
mind that you want under 3% and under 1200 ppm HC. set it to about 2-2.5%
CO should work reasonably well. adjust this using the smaller screw. You
ought to have some gas going through this part of the vapouriser, or it can
cut out when coming to a halt. If it's still too rich even with the 8mm
head screw shut, then turn the 10mm head screw in a bit, to increase the
diaphragm tension and make it leaner, then take the 8mm head screw out a bit
to get the idle mixture nice. aim if possible at about 1/2 turn out on the
8mm head screw.
go back to 3000 rpm, and see what this has done to your CO there, and if
necessary, tweak the max. flow to get it back to 1.0%
now reconnect the ecomax vacuum pipe, and, if the ecomax is working, watch
the CO go *way* down. The ecomax is adjusted by rotating the top of it (you
might have to pull the pipe off and untwist it :-)) - screwing it in makes
the mixture *richer*. Adjust the ecomax to give about 0.15%-0.2% CO at 3000
rpm (this is why you need a good gas analyser), with minimum HC (should get
the HC down around 300 without too much trouble unless you're burning a lot
of oil. If you get the CO too low, the HC can go up again.
finally, leaving the ecomax on, drop back to idle and check the idle
figures.
have fun...
oh yeah, one final thing - if it's feasible, you can connect the LPG outlet
pipe to the lower outlet on the vap., which allows it to draw the heavy ends
out of the vap. instead of them collecting there; move the blanking thing to
the top outlet.
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Remember that to change your mind and follow him who sets you right
is to be none the less free than you were before."
Marcus Aurelius Antoninus (121-180), from Meditations, VIII.16
Al-bags
"Austin Shackles" wrote loads about Range-Rover adjustments
Nice little procedure, Austin !.
Only thing Id add would be-The amount that the main gas volume has to be
open, is relative to the draw on the vaporiser, therefore the diameter of
the venturi, and area of the discharge drillings in that venturi. (and a few
teeny variants that aint worth talking about ! ) : )
Bags
Autolycus
"Austin Shackles" <aus...@ddol-las.fsnet.co.uk> wrote in message
news:mfv4fusdopun1euq1...@4ax.com...
> On or around Mon, 27 May 2002 18:21:02 +0100, "Autolycus"
> <lidcof...@ntlworld.com> enlightened us thusly:
>
> >
> >Following up my own earlier post about running problems with the
Range
> >Rover,
> okay...you asked:
>
<snip super explanation of setting up OMVL>
Thanks *very* much. I wish the Chris Perfect /Iwema explanation had
been anywhere near as good.
I really must try to get the gas analyser working: it's a proper piece
of kit "Gas Check 2000", which I was given free with the four post lift
I bought because it had taken an unscheduled flight from a bench.
Occasionally it works perfectly, but usually it displays either nothing
or strange numbers like 3552 for the CO zero setting.
Either that or hope the MoT man is co-operative tomorrow. I've printed
the notes to take with me.
>
> have fun...
>
ho yus.
> oh yeah, one final thing - if it's feasible, you can connect the LPG
outlet
> pipe to the lower outlet on the vap., which allows it to draw the
heavy ends
> out of the vap. instead of them collecting there; move the blanking
thing to
> the top outlet.
>
That one may have to wait till I have to dismantle it all to replace the
inner wing. Which could be tomorrow, I suppose, if he gets it in his
head that an inner wing is somehow "structural" on a Rangey.
Austin Shackles
<Al...@babykench.fsnet.co.uk> enlightened us thusly:
If the kit is still as supplied, the mixers should be correct for the job.
The nice man at Iwema did quite a lot of work on this to get it right...
Austin Shackles
<lidcof...@ntlworld.com> enlightened us thusly:
>
>"Austin Shackles" <aus...@ddol-las.fsnet.co.uk> wrote in message
>news:mfv4fusdopun1euq1...@4ax.com...
>> On or around Mon, 27 May 2002 18:21:02 +0100, "Autolycus"
>> <lidcof...@ntlworld.com> enlightened us thusly:
>>
>> >
>> >Following up my own earlier post about running problems with the
>Range
>> >Rover,
>
>> okay...you asked:
>>
><snip super explanation of setting up OMVL>
>
>Thanks *very* much. I wish the Chris Perfect /Iwema explanation had
>been anywhere near as good.
well, most of my info comes from there, plus experience on my vehicles of
course... The latest instructions that Chris sends out with kits (I live
about 4 miles from him...) are pretty good.
>I really must try to get the gas analyser working: it's a proper piece
>of kit "Gas Check 2000", which I was given free with the four post lift
>I bought because it had taken an unscheduled flight from a bench.
>Occasionally it works perfectly, but usually it displays either nothing
>or strange numbers like 3552 for the CO zero setting.
hehe...