V12 Ignition question
#1
V12 Ignition question
Hi all,
I've been working through all of the maintenance and tuning issues on my 88 xj-sc that I bought 2 months ago. The car is in excellent condition with 27,000 miles, but like many, suffers from nearly 16 years of sitting idle, and some misguided maintenance as well.
I've changed plugs, wires, cap and rotor, repaired sensor connections etc. Also did the basics on the throttle side; TPS, linkage bushings, etc.
Here's my main question:
Using the "advance and test drive" method to get to an optimum timing position, and have advanced the distributor until the cam-driven adjustment has run out of range. Probably have advanced it in the neighborhood of 8-10 degrees, although that's just a guess. The car is running far better, although still feels a tad underpowered, and still has a slightly rough idle that may or may not be related to this. There is no pinging, or even a hint that I've gone too far. Have access to, and use 93 octane fuel here in Minnesota.
Is it likely that the entire distributor needs to be rotated a little to provide more adjustment range? Is that done via the slotted adjustment with the Allen bolts that is just below the distributor base?
Also wondering if this is a sign that I'm not getting the centrifugal or vacuum advance that I should be. The rotor will snap back reasonably well when turned by hand, but the range seems pretty limited based on where it sits in the slots on the clear plastic dust cover.
Appreciate any input!
Thanks,
Chris
I've been working through all of the maintenance and tuning issues on my 88 xj-sc that I bought 2 months ago. The car is in excellent condition with 27,000 miles, but like many, suffers from nearly 16 years of sitting idle, and some misguided maintenance as well.
I've changed plugs, wires, cap and rotor, repaired sensor connections etc. Also did the basics on the throttle side; TPS, linkage bushings, etc.
Here's my main question:
Using the "advance and test drive" method to get to an optimum timing position, and have advanced the distributor until the cam-driven adjustment has run out of range. Probably have advanced it in the neighborhood of 8-10 degrees, although that's just a guess. The car is running far better, although still feels a tad underpowered, and still has a slightly rough idle that may or may not be related to this. There is no pinging, or even a hint that I've gone too far. Have access to, and use 93 octane fuel here in Minnesota.
Is it likely that the entire distributor needs to be rotated a little to provide more adjustment range? Is that done via the slotted adjustment with the Allen bolts that is just below the distributor base?
Also wondering if this is a sign that I'm not getting the centrifugal or vacuum advance that I should be. The rotor will snap back reasonably well when turned by hand, but the range seems pretty limited based on where it sits in the slots on the clear plastic dust cover.
Appreciate any input!
Thanks,
Chris
#2
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Grant Francis (06-26-2019)
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Also wondering if this is a sign that I'm not getting the centrifugal or vacuum advance that I should be. The rotor will snap back reasonably well when turned by hand, but the range seems pretty limited based on where it sits in the slots on the clear plastic dust cover.
Also, Jaguar used a really complicated vacuum advance control system. It's plausible that one or more of the components are the blink. many ditch the whole mess and run a vac hose right to the unused spigot beneath the RH throttle body.
(Or is it above the RH throttle body? Gah ! Someone will clarify I've had a long day )
Cheers
DD
The following 2 users liked this post by Doug:
Grant Francis (06-26-2019),
Greg in France (06-27-2019)
#6
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,920
Received 10,979 Likes
on
7,211 Posts
Hi all,
I've been working through all of the maintenance and tuning issues on my 88 xj-sc that I bought 2 months ago. The car is in excellent condition with 27,000 miles, but like many, suffers from nearly 16 years of sitting idle, and some misguided maintenance as well.
I've changed plugs, wires, cap and rotor, repaired sensor connections etc. Also did the basics on the throttle side; TPS, linkage bushings, etc.
I've been working through all of the maintenance and tuning issues on my 88 xj-sc that I bought 2 months ago. The car is in excellent condition with 27,000 miles, but like many, suffers from nearly 16 years of sitting idle, and some misguided maintenance as well.
I've changed plugs, wires, cap and rotor, repaired sensor connections etc. Also did the basics on the throttle side; TPS, linkage bushings, etc.
Good work. You've already covered a lot of ground.
Cheers
DD
#7
The following users liked this post:
Doug (06-26-2019)
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#8
The following users liked this post:
Grant Francis (06-27-2019)
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