The ongoing work on my 1992 Sovereign V12, nears completion. After
nearly 5 weeks in the garage and 4 weeks in the body shop, and a
lot more work than was originaly envisaged. The car will be back
for the weekend.
The distributor has been removed and striped down, and no
mechanical centrifugal mechanism is included! This is one of the
last Series 3 V12s from 1992 UK. It has a correctly functioning
vacuum advance, and is a closed loop car. Sort of a ‘‘cross’’
between N.American spec and UK.
The Jaguar specialists advises me they have seen a few late ones
like this. I am assuming the ecu can not replace the centrifugal
mechanism as it can not control firing???
I am a little confuse, any one have any experience with this?
Cheers
Jamie–
Newtown, Powys, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
The ongoing work on my 1992 Sovereign V12, nears completion. After
nearly 5 weeks in the garage and 4 weeks in the body shop, and a
lot more work than was originaly envisaged. The car will be back
for the weekend.
The distributor has been removed and striped down, and no
mechanical centrifugal mechanism is included! This is one of the
last Series 3 V12s from 1992 UK. It has a correctly functioning
vacuum advance, and is a closed loop car. Sort of a ‘‘cross’’
between N.American spec and UK.
The Jaguar specialists advises me they have seen a few late ones
like this. I am assuming the ecu can not replace the centrifugal
mechanism as it can not control firing???
I am a little confuse, any one have any experience with this?
I’m a bit confused too, James - I have heard making do without the
vacuum advance, but not without some sort of centrifugal…?
Modern ignition timing is of course routinely electronically controlled,
but that is beyond the garden variety of our ECUs. Point is; do you have
a crank sensor instead of the timing marks - it would reveal electronic
timing control…
In reply to a message from Frank Andersen sent Thu 31 Jul 2008:
Thanks Frank
It is ‘‘standard’’ factory Jaguar ignition, nothing aftermarket. I
will look to see if I can find a CPS when I get the car back
tomorrow, but I do not think for one minute I will find one.
Could they have designed the vac advance to be controlled in some
way, to replace the centrifugal. Although I can not see how on the
face of it?
The timing light showed a change when the engine speed was
accelerated.
Jamie–
The original message included these comments:
I’m a bit confused too, James - I have heard making do without the
a crank sensor instead of the timing marks - it would reveal electronic
I find that very odd, as I’ve not heard of that from other 92 owners, my
car included. A centrifugal advance was definitely there on my car, and
when its properly functioning it does make a noticeable improvement in
fuel economy. I suggest it was either a defect from the factory, or
someone has been in there before and taken it out for some reason. The
ECU isn’t smart enough to provide advance, as there is no way for the
ECU to change the advance of the spark.
I’d get another distributor, strip it down and clean and lubricate
everything. I’ve found that using synthetic ATF makes a very good
lubricant for the advance weights, and it won’t gum up over time like
regular oil does. Be careful with reassembly, I have photos of the
process somewhere, I’ll have to see if I can find them.
Craig
ghound wrote:>The Jaguar specialists advises me they have seen a few late ones
like this. I am assuming the ecu can not replace the centrifugal
mechanism as it can not control firing???
Jamie: I have owned a number of the last 1992 V12 cars (Canadian
specification). They all have the vacuum advance mechanism on them and as
far as I know the mechanical weight system is in the distributor exactly as
it was on all the Series III V12 cars. This is one part of the V12 that did
not change. One of the service areas on the V12 is precisely to make sure
that the advance mechanism is not clogged with old and solidified grease.
The distributor has been removed and striped down, and no
mechanical centrifugal mechanism is included! This is one of the
last Series 3 V12s from 1992 UK. It has a correctly functioning
vacuum advance, and is a closed loop car. Sort of a ‘‘cross’’
between N.American spec and UK.
The Jaguar specialists advises me they have seen a few late ones
like this. I am assuming the ecu can not replace the centrifugal
mechanism as it can not control firing???
Frank:
There never was an electronic timing control on the 5.3 litre V12, no crank
sensor - even on the very last Series III V12.
Gregory
1966 Mark 2 3.8
1992 Series III V12 Vanden Plas (#92 of the last 100)
2002 X-Type
2004 XJ8 4.2-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf Of
Frank Andersen
I’m a bit confused too, James - I have heard making do without the
vacuum advance, but not without some sort of centrifugal…?
Modern ignition timing is of course routinely electronically controlled,
but that is beyond the garden variety of our ECUs. Point is; do you have
a crank sensor instead of the timing marks - it would reveal electronic
timing control…
In reply to a message from Dr. Gregory Andrachuk sent Thu 31 Jul 2008:
I will be fully investigating this on the weekend. Initially after
asking some very knowledgeable Jaguar specialist, the only way it
could be; is if a 1992 5.3 TWR engine is in place. However I think
not, as from memory all the ignition system looks standard.
As I say, I will investigate further when I have the car back.
Jamie–
The original message included these comments:
There never was an electronic timing control on the 5.3 litre V12, no crank
Those engines were bored out to 6 litres and used the Zeytec ignition
system, and were all very unique and used in the XJRS. As far as I know
they used distributorless ignition, but I could be wrong on that. I’m
99.99% sure those engines never found their way into the Series III
body, unless it’s been a retrofit. If you have the Lucas ignition module
on the intake manifold there should be a centrifugal advance in your
distributor.
Craig
ghound wrote:>In reply to a message from Dr. Gregory Andrachuk sent Thu 31 Jul 2008:
I will be fully investigating this on the weekend. Initially after
asking some very knowledgeable Jaguar specialist, the only way it
could be; is if a 1992 5.3 TWR engine is in place.
In reply to a message from Craig Talbot sent Thu 31 Jul 2008:
The XJR-S had a 6.0L engine handbuilt by Tom Walkinshaw
Racing. It wasn’t put into anything else, although there were
a couple bespoke Series III V12 sedans which were retrofitted
by Lister with similarily modded V12s. These modifications
involved tremendous cost, and resulting in somewhat of a
glorious frankenstein car with a monster 7.0L engine and
hammered out wheel wells to support huge wheels with racing
calipers. I think there were only 3 or 4 made, so the chances
of you ending up with one unwittingly are slim…
-Chris–
The original message included these comments:
Those engines were bored out to 6 litres and used the Zeytec ignition
system, and were all very unique and used in the XJRS. As far as I know
they used distributorless ignition, but I could be wrong on that. I’m
99.99% sure those engines never found their way into the Series III
body, unless it’s been a retrofit. If you have the Lucas ignition module
on the intake manifold there should be a centrifugal advance in your
distributor.
In reply to a message from Frank Andersen sent Thu 31 Jul 2008:
Thanks Frank
It is ‘‘standard’’ factory Jaguar ignition, nothing aftermarket. I
will look to see if I can find a CPS when I get the car back
tomorrow, but I do not think for one minute I will find one.
Could they have designed the vac advance to be controlled in some
way, to replace the centrifugal. Although I can not see how on the
face of it?
Neither can the rest of us, James! POs do the strangest things, but
simply vacuum cannot effectively control ign timing…
About the change of timing, any numbers on that advance compared to
engine rpms advance should increase at a predetermined rate with
increasing rpms. As the vacuum is connected it will also alter advance,
but it will be fairly constant through most of the rev range…
Frank
xj6 85 Sov Europe (UK/NZ)>The timing light showed a change when the engine speed was
In reply to a message from Frank Andersen sent Fri 1 Aug 2008:
The car is back home:
A quick look agrees with my memory, a standard ignition amp etc.
Tomorrow I will strip down the alternator for further
investigations. I have also acquired a good spare one, complete
with centrifugal mechanism.
On the 140 mile trip back, the trip computer showed 23mpg, running
standard UK 95ron unleaded, acceleration and wot all felt fine.
Mixed Motorway/Dual Carriageway and A roads 60-90 mph.
Thanks all, will hopefully report back once distributor is opened
up.
Jamie–
The original message included these comments:
Neither can the rest of us, James! POs do the strangest things, but
A quick look agrees with my memory, a standard ignition amp etc.
Tomorrow I will strip down the alternator for further
investigations. I have also acquired a good spare one, complete
with centrifugal mechanism.
On the 140 mile trip back, the trip computer showed 23mpg, running
standard UK 95ron unleaded, acceleration and wot all felt fine.
Mixed Motorway/Dual Carriageway and A roads 60-90 mph.
Thanks all, will hopefully report back once distributor is opened
up.
I’m not sure you should, Jamie - whatever is in there seems to work just
fine…
In reply to a message from ghound sent Fri 1 Aug 2008:
Just a thought…if it appears to be running fine, and mileage is
good, why wouldn’t you just leave it as is?..–
1977 XJ6C , 1988 XJ-S H&E
skaneateles, ny, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from 345 DeSoto sent Sat 2 Aug 2008:
As part of fully recommissioning the car, checking the centrifugal
advance and ensuring it’s lubricated is recommended with the V12.
Hence why it was striped down.
Jamie–
The original message included these comments:
In reply to a message from ghound sent Sat 2 Aug 2008:
For the record, the car most certainly has a centrifugal mechanism
and it is, and was working. I striped it down today to check.
Now not believing anything after this, I have also checked the
vacuum advance and this works, although some one has removed the
valve in the vacuum line. I assume this missing valve is a one way
device?
There should be a regulator, as the V12 maxs out at 12" Hg, full
manifold vacuum isn’t applied to the capsule. Take al look at AJ6
Engineering’s website, they have a good discussion of the V12’s vacuum
advance mechanism.
Craig
ghound wrote:>Now not believing anything after this, I have also checked the
vacuum advance and this works, although some one has removed the
valve in the vacuum line. I assume this missing valve is a one way
device?
In reply to a message from ghound sent Sat 2 Aug 2008:
For the record, the car most certainly has a centrifugal mechanism
and it is, and was working. I striped it down today to check.
Now not believing anything after this, I have also checked the
vacuum advance and this works, although some one has removed the
valve in the vacuum line. I assume this missing valve is a one way
device?
Not a one-way valve, Jamie…
On the European HE V12s there is an electrically operated three-way
valve wich switches between two vacuum sources depending on engine oil
temps. On the US models a dump valve is used to conrol dist vacuum,
adding an in-line ‘delay’ valve - which is basically a restrictor to
avoid sudden changes to dist vacuum. On other ‘plain’ set-ups sometimes
a (two-way) restrictor is used for the same purpose…
