[xj-s] Timing question

XJ-S
1

I’m just finishing up with the (Lucas CEI) distributor off
my '85 V-12, having Kirby-ed it (disassembled, cleaned and
rebuilt as per ‘The Book’),
It occurs to me that I might need to use a timing light when
finally adjusting the distributor. My (20 year) old timing
light has a label indicating it can safely be used on 4, 6
and 8 cylinder engines. Do any of the sages know if I can
use it on a 12 cylinder ? I am guessing that it will work,
but any thoughts/advice would be appreciated.

Dave

1985 XJ-S Coupe HE V-12
1990 XJ-S Convertible Classic Collection V-12
1983 XJ6 Vanden Plas–
Tefba filters at http://carbitz.org
Los Angeles, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

// please trim quoted text to context only

2

Dave, the 20 year old timing light will work on the V12. If it’s not an
inductive type (clamp goes over A1 plug wire) you’ll have a hard time
getting to the A1 plug to insert the old style junction connector. If you
have a mechanical fan, be very careful of the fan and other belts. It is
safest to run the pick-up wire up from the bottom and connect it to the plug
wire and then temporarily wire-tie it clear of all moving parts after
putting the car on stands to check the timing at the crankshaft dampener.
The first time I did mine, I ran the engine and carefully held emory paper
against the dampener (it was clean) from the bottom to make it “bright” and
then put a dab of white paint at the timing mark (the " I " line, not the
“A”) and it was much easier to see when adjusting the timing. If the light
is DC and you use a second battery (don’t use a battery charger) to power
the light - rather than running wires to the boot - be sure to run a
temporary ground wire from the second battery to the engine or chassis.

Jim Johnson - NCJOC
'88 XJ-S, V12, Lucas (CEI), TH400 (w/B&M), Dana 2.87
Annapolis, Maryland

// please trim quoted text to context only

3

In a message dated 8/21/2004 11:47:28 PM Eastern Daylight Time, “1985 Coupe” xjs@earthlink.net writes:

It occurs to me that I might need to use a timing light when
finally adjusting the distributor. My (20 year) old timing
light has a label indicating it can safely be used on 4, 6
and 8 cylinder engines. Do any of the sages know if I can
use it on a 12 cylinder ?

Dave:

A “sage” has already responded (Jim knows Jags) but I’ll add my $.02: the timing light I use is also older than the car and it works fine. I would suggest connecting the two battery leads of the light to a separate (spare) battery rather than running jumpers to the trunk or trying to connect elsewhere, but as Jim suggests, connect the ground of the spare battery to the vehicle chassis or you will jolt yourself with HT voltage.

Make sure you route the plug wire connector of the light Safely over the fan & tape it down. I pull the 1A plugwire from the distributor and put the light connection there. You may need to use aluminum foil or such to make the correct wire size.

The specified setting is 18 degrees BTDC @ 3,000 RPM, vacuum advance hose removed & plugged. If your centrifugal advance is working properly (which of course your’s should now be) you should get 0 Degrees BTDC (NO advance) at 600 RPM idle, plus/minus 1-2 degrees, also with the vacuum advance hose removed & plugged.

It’s a bit daunting to get under that thing revving @ 3,000 RPM, but it’s the best way to get it right. As Jim suggests, paint marks, or at least cleaning thoroughly so you can find the alignment marks, help greatly. Make SURE you’ve got good stands & chocks. Also, be very gentle with the screw & locking nut on the distributor vernier, as this whole fragile assembly is frequently broken off by using more than inch-pound range torque.

You are in for a real treat if your distributor was seized before–it will feel like an entirely different car. Just make sure your kickdown switch is operating properly, because you’ll want to use first to high RPM a LOT :wink:

George Balthrop, Clifton, VA USA
85 & 89 XJ-S Coupes; 89 XJ40 VDP

// please trim quoted text to context only