The setting of the ignition timing is different depending on
the engine and ignition type.
Pre HE 5.3
HE 5.3 Lucas
5.3 Marelli
3.6
5.3 & 6.0 Zytec TWR XJRS
4.0 AJ6
4.0 AJ16
6.0
This is for the HE 5.3 V12 Lucas.
There is a static setting for assembly of the engine so it
will run at the finish of the build. I could not find this
for the HE.
Emissions caused vacuum systems to be varied and complex.
There were A, B, C and D systems with varying combinations
of vacuum advance components. 1-Water Temp Switch, 2-Time
Delay Module, 3-Vacuum Regulator, 4-Vacuum Delay Valve,
5-Vacuum Dump Valve, 6-3Way Solenoid Valve, 7-2Way Solenoid
Valve, 8-Solenoid Air Switch, 9-Distributor Advance Capsule,
9-Throttle Edging Tapping.
There are 5 modes of operation and you cannot set the timing
during these modes. You must set by disconnecting the
vacuum and running the engine at 3000 RPM to 18 deg ± 2 deg
BTDC at normal operating temp. The modes are:
Idle cold below 38 deg C engine temp
Light Throttle cold below 38 deg C below 4000 RPM
Vacuum Dumping Operation
Idle hot above 45 deg C
Light Throttle hot above 45 deg C
If the throttles are not set properly there may be vacuum
through the Throttle Edge Tapping. There may be a 45 second
inhibit of the vacuum signal at start to light the converts.
Coolant temp being off may cause vacuum changes. Rapid
open and closing of the throttle may cause vacuum signal delay.
There are distributor RPM advance degree numbers for
checking the distributor on a distributor machine. The
Haynes manual has an error. The factory setting for the 5.3
HE is 18 deg ± 2 at 3000 RPM.–
Geoff Green 63 OTS 76 XJS 95 XJS
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Geoff Green sent Wed 28 Jul 2010:
well, great help Geoff. Tomorrow I will try to set it to -+ 18 deg
BTDC. Now it operates at 0deg … I wonder how this worked so long -
eventhough car was barely used (2-3months a year).
I just wonder if 18 deg difference can be adjusted with vernier ?
well, great help Geoff. Tomorrow I will try to set it to -+
18 deg
BTDC. Now it operates at 0deg … I wonder how this worked
so long -
eventhough car was barely used (2-3months a year).
I just wonder if 18 deg difference can be adjusted with
vernier ?
Bart,
The mechanical advance weights are active and maxed out at 3000 RPM. Disconnecting the vacuum eliminates any variance from the vacuum part of the system. This causes the timing to be about 18 degrees. You many not have to adjust anything. Check your mechanical advance before setting the timing.
In reply to a message from Geoff Green sent Wed 28 Jul 2010:
when I first got my car the timing appeared to be well out when
using a strobe, it turned out the cone behind the crank pully had
broke into 3 pieces and the pully was a free spirit, not unusual
occurrence I have since discovered–
The original message included these comments:
In reply to a message from Geoffrey Green sent Wed 28 Jul 2010:
Currently it is 0-2 deg with vacuum off - well retarted in my
opinion. With vacuum line connected there was a little difference
at idle. No wonder I couldnt break 2000rpms while driving…–
memento1984
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Currently it is 0-2 deg with vacuum off - well retarted in
my
opinion. With vacuum line connected there was a little
difference
at idle. No wonder I couldnt break 2000rpms while
driving…
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
8
memento1984 wrote:
Currently it is 0-2 deg with vacuum off - well retarted in my
opinion.
Yeah, but WHY? Did someone move the distributor? Or is something
jammed or broken?
– Kirbert
// please trim quoted text to context only
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
9
memento1984 wrote:
vacuum off:
750rpm - -2 to 0 deg
2000rpm - -2 to 0 deg
3000rpm - -2 to 0 deg
Your centrifugal advance mechanism is seized. Rebuild the
distributor before doing anything else.
vacuum on:
750rpm - 0 to 2 deg
2000rpm - 0 to 2 deg
Hmmmm. I presume this is in neutral, no load on engine? Still, this
doesn’t look right. Presuming you’re getting the butterflies open
far enough to get past the throttle edge tap, I’d expect the vacuum
advance to go up more than this. While you have the distributor
apart to fix the centrifugal mechanism, check the vacuum capsule.
The diaphram inside may have gotten hard.
In reply to a message from Kirbert sent Thu 29 Jul 2010:
Kirby,
What would be the expected advance with vacuum hose connected ? How
many degrees difference?
Best Regards,
Bart–
memento1984
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
It would appear that NEITHER your vacuum advance, NOR your centrifugal
advance mechanisms are working.
0 to 2 degrees BTDC is the correct timing reading at 750 RPM idle speed
with the vacuum advance hose removed and plugged. However, if your
vacuum advance system were working, when you attached the vacuum hose
to the vacuum advance unit, the timing should be ~ 16 degrees BTDC at
750 RPM idle. If the timing does NOT change at idle when you connect
the vacuum hose, either there is no vacuum proviced by the hose, the
vacuum advance unit is bad (this is the most likely problem), or the
vacuum advance unit is disconnected inside the distributor.
If the advance does NOT change (with the vacuum hose disconnected and
plugged) when increasing engine RPM from idle to 3,000 RPM (where it
should now read ~ 18 degrees BTDC), then your centrifugal advance
mechanism is seized. You can confirm that by removing the distributor
cap and attempting to rotate the rotor counterclockwise ~ 12 degrees
against spring pressure. It should rotate that distance against spring
pressure, and snap back with a click when released. If if does not,
then you need to remove your distributor and rebuild it per the Book.
George Balthrop, Clifton, VA USA
89 and 85 XJ-S Coupes; 89 XJ40 VDP-----Original Message-----
From: memento1984 bartprzychodzen@yahoo.com
vacuum off:
750rpm - -2 to 0 deg
2000rpm - -2 to 0 deg
3000rpm - -2 to 0 deg
vacuum on:
750rpm - 0 to 2 deg
2000rpm - 0 to 2 deg
// please trim quoted text to context only
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
12
memento1984 wrote:
What would be the expected advance with vacuum hose connected ? How
many degrees difference?
I dunno off the top of my head. I know it goes from a small amount
of advance at idle to a large amount (12 degrees or so) at light
throttle and back to none at full throttle.
It’s easier to tell if the vacuum module is OK by just fiddling with
it. I had one in my hand that when you moved the rod, you heard a
crunch, and from then on it was a rattle. That’s not good.
In reply to a message from Les Marston sent Thu 29 Jul 2010:
just to confirm:
if the centrifugal system is seized (totally), would this affect
vacuum system ? the vacuum system drags the pin back, but someone
on the forum (or kirby?) suggested that it is not holding it in
place, but smoothly releases it.
in my case it should drag it and smoothly release (looks like it at
least) - I suspect it was not connected with arm.
It is the old style, never replaced imho.
In reply to a message from Geoff Green sent Wed 28 Jul 2010:
I just realized one thing - when I was testing vacuum advance on
the car running, I didnt allow for 15min, to vacuum advance to kick
in!
I just found it while reading Kirby book again.
Vacuum unit does not behave like cracked/fried and hard inside.–
memento1984
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
The centrifugal and vacuum advance systems are totally separate in
their operation, with neither affecting the other.
The centrifugal advance operates by having the rotor carrier rotate on
the distributor shaft. In instances such as your where you can’t turn
the rotor counterclockwise against spring pressure, the rotor carrier
is seized to the distributor shaft, and this assembly needs to be
dismantled, cleaned, and lubed with synthetic oil to restore proper
operation.
The vacuum advance operates by rotating the distributor pickup relative
to the 12-point star mounted on the distributor shaft. Applying vacuum
to the vacuum module SHOULD make the shaft on the module move, and this
shaft should be connected to a pin on the pickup module so that the
module is rotated by the application of vacuum.
The vacuum module SHOULD hold vacuum, such that the shaft should move
with application of vacuum, and REMAIN in that position, rather than
“leaking back” to a “no-vacuum” position.
George Balthrop, Clifton, VA USA
89 and 85 XJ-S Coupes; 89 XJ40 VDP-----Original Message-----
From: memento1984 bartprzychodzen@yahoo.com
if the centrifugal system is seized (totally), would this affect
vacuum system ? the vacuum system drags the pin back, but someone
on the forum (or kirby?) suggested that it is not holding it in
place, but smoothly releases it.
in my case it should drag it and smoothly release (looks like it at
least) - I suspect it was not connected with arm.
// please trim quoted text to context only
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
18
memento1984 wrote:
So I just removed the distro with housing - the mechanical advance is
seized. it is all tight, You cannot really move the springs.
We knew that.
when I tried to to test the advance with rubber hose and my mouth, it
was not holding it.
Not necessarily indicative, since some of them were made with
deliberate leaks. More important: When you sucked on it, did it
move? If it didn’t move, it needs replacement.
It’s possible to rebuild it using a Chevy diaphragm. That’s really
only for those who enjoy such fiddling, though. For most, the
solution is a new vacuum module.