In a message dated 8/21/2004 11:47:28 PM Eastern Daylight Time, “1985 Coupe” email@example.com 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 ?
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
George Balthrop, Clifton, VA USA
85 & 89 XJ-S Coupes; 89 XJ40 VDP
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