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1977 XJ-S

Starbuck
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Location: Melbourne, Australia

Re: 1977 XJ-S

Postby Starbuck » Fri Oct 14, 2016 1:18 pm

Hi Leo,

If you can get the Jaguar coil for a reasonable price there is no reason to use the Bosch unit. The single Jaguar coil is what is recommended and it will be the correct low impedance type. It is a good idea to 'chase' the redundant wiring for the second coil and make sure it has all been removed when the engine was installed in your car, or at least properly insulated if not completely removed so it can't cause any shorts.

Cap, rotors and plugs are very easy to find. Buy a good quality rotor and cap - much easier to do with the older Lucas single row distributor than with the later Marelli twin row.

Make sure you have a nice new piece of fuel hose handy that will fit over the insulator of the spark plugs - it makes it much easier to get the plug in and started in the thread without having to remove everything from the valley. It is also a very good idea to get the vacuum cleaner out (hoover - for you British types ;) ), to vacuum up any dirt etc from around the spark plug holes before you remove the plugs. Do the same thing again once the plug has been removed. Use pure Molybdenum Disulphide 'graphite' grease (not copper anti-seize) on the threads and taper seats as this will make it easier to remove them - do not use the factory torque figures for the plugs if using anti-seize as they will then be too tight - literally just a little more than finger tight.

Best,

Starbuck
'94 XJ12 (and other toys)

leo_denmark
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Posts: 720
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Location: Denmark

Re: 1977 XJ-S

Postby leo_denmark » Sat Oct 15, 2016 7:37 pm

Starbuck wrote:Hi Leo,

If you can get the Jaguar coil for a reasonable price there is no reason to use the Bosch unit. The single Jaguar coil is what is recommended and it will be the correct low impedance type. It is a good idea to 'chase' the redundant wiring for the second coil and make sure it has all been removed when the engine was installed in your car, or at least properly insulated if not completely removed so it can't cause any shorts.

Cap, rotors and plugs are very easy to find. Buy a good quality rotor and cap - much easier to do with the older Lucas single row distributor than with the later Marelli twin row.

Make sure you have a nice new piece of fuel hose handy that will fit over the insulator of the spark plugs - it makes it much easier to get the plug in and started in the thread without having to remove everything from the valley. It is also a very good idea to get the vacuum cleaner out (hoover - for you British types ;) ), to vacuum up any dirt etc from around the spark plug holes before you remove the plugs. Do the same thing again once the plug has been removed. Use pure Molybdenum Disulphide 'graphite' grease (not copper anti-seize) on the threads and taper seats as this will make it easier to remove them - do not use the factory torque figures for the plugs if using anti-seize as they will then be too tight - literally just a little more than finger tight.

Best,

Starbuck


MoS2 graphite grease you say.

I have happily been using copper grease for decades for this, but I know there is some talk about electric potential and corrosion when applied to alu parts.
I've bought some 'aluminium' grease for use on brake caliber guides to reduce the risk there on Alfas, Fiats and other inferior cars using alu calipers, but mounting paste with MoS2 is not something I have in my work.

Most things that pop up when googling 'Molybdenum Disulphide 'graphite' grease' is ordinary lithium NLGI2 grease spiced up with a few percent MoS2. I guess that is not what you are suggesting ?
BR Leo Jensen - Denmark
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XJ40 3.2 LHD 1992 (VIN: ...660341). Owned since Nov 9th 2005
XJ-S V12 coupe 1977 (SW53309BW). Owned since April 28th 2016. http://www.xj-s.dk/home/
Citroën 2CV 1975. Owned since Sep 1st 1984
Board member of Jaguar Club of Denmark

Starbuck
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Location: Melbourne, Australia

Re: 1977 XJ-S

Postby Starbuck » Sun Oct 16, 2016 5:56 am

Hi Leo,

Yep, galvanic corrosion is one of the main reasons not to use copper-based anti-seize on anything with aluminium, particularly on spark plugs because they will be grounded via the copper. This is not a particularly happy combination in the longer term.

Usually the same places that carry the small containers of copper-based anti-seize also carry small containers of high content molybdenum disulphide grease, and this is a much better bet for spark plugs. It's horrible stuff if you get it on your skin or clothes as it is almost impossible to wash off, but it is good for plugs in alloy heads (bearing in mind my comments about tightening torque).

Best,

Starbuck
'94 XJ12 (and other toys)

leo_denmark
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Location: Denmark

Re: 1977 XJ-S

Postby leo_denmark » Sun Feb 19, 2017 12:43 pm

Spark plug indexing question:

Plugs are ready to be installed, including the correct thread lubricant, gapped and side electrode position marked on top of the spark plugs.

Some months ago I figured out that the side electrode attachment point should be facing outwards compared to engine center, i.e. to the right and a bit forward on A1-2-3 and so on.
Now I'm in doubt if it's correct.

Any quick tips out there, or should I start looking at valve and spark plug hole positions to convince myself it's correct... ?
BR Leo Jensen - Denmark
Image
XJ40 3.2 LHD 1992 (VIN: ...660341). Owned since Nov 9th 2005
XJ-S V12 coupe 1977 (SW53309BW). Owned since April 28th 2016. http://www.xj-s.dk/home/
Citroën 2CV 1975. Owned since Sep 1st 1984
Board member of Jaguar Club of Denmark

leo_denmark
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Posts: 720
Joined: Sun Sep 11, 2011 6:32 pm
Location: Denmark

Re: 1977 XJ-S

Postby leo_denmark » Sun Feb 19, 2017 2:06 pm

I've concluded it must be the other way round: the spark gap must point outwards and the side electrode attachment point must therefore point towards the engine valley.
BR Leo Jensen - Denmark
Image
XJ40 3.2 LHD 1992 (VIN: ...660341). Owned since Nov 9th 2005
XJ-S V12 coupe 1977 (SW53309BW). Owned since April 28th 2016. http://www.xj-s.dk/home/
Citroën 2CV 1975. Owned since Sep 1st 1984
Board member of Jaguar Club of Denmark

SovverBovver
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Location: In a garage

Re: 1977 XJ-S

Postby SovverBovver » Sun Feb 19, 2017 10:51 pm

leo_denmark wrote:I've concluded it must be the other way round: the spark gap must point outwards and the side electrode attachment point must therefore point towards the engine valley.


Are you going to index your plugs? I'd be interested to see what you thought of the results if you did. I heard this was a bit of "an old wives tale"? But others say it helps...
1992 Jaguar Sovereign

Starbuck
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Re: 1977 XJ-S

Postby Starbuck » Mon Feb 20, 2017 1:44 am

Hi Leo,

'Indexing' plugs is not worth the effort on anything but a small capacity high horsepower race car. This is even more the case with the HE 'squish head' chambers because they have so much intake mixture swirl that plug indexation will have no effect on ignition.

Anyway, the only way to do it with production plugs and heads is to mark the plug, torque the plug correctly and note where the electrode ends up, and then try the plug in a number of different chambers until you get the electrode where you want it. The HE tapered-seat plugs do not have enough 'wriggle room' with the tightening torque to allow you to adjust the angle a little either side - you only have to over-torque one slightly and you will be in a world of hurt when it comes to taking it out. This means you could go through several sets of plugs looking for just the right threads and electrode alignment combination before you got it right.

If using molybdenum disulphide grease remember to reduce your plug torque figures by 33%. This is also critical if you want to get the plugs out again in the future (I'm presuming you do!).

Best,

Starbuck
'94 XJ12 (and other toys)

leo_denmark
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Location: Denmark

Re: 1977 XJ-S

Postby leo_denmark » Mon Feb 20, 2017 10:59 am

Hi

Here's how I did it

First I removed more or less everything in the V. I'm replacing spark plug cables, coil, dizzy cover and rotor anyway, so it was not a big issue to get piping, capstan and compressor out of the way as well.

I then added a side electrode position marking on top of all plugs.

All plugs was then torqued in 2A, and I noted the position of the marking (2 o'clock and so on). Now I knew how the side electrode position distribution was on the plug sample I had. The distribution was not pretty, 11 of them was on the same 180°/6 hours.
This meant I had to aim for acceptable rather than perfect, but using the spread of thread start angle in the head helped me.
By mounting, swapping and comparing for 2 hours I ended up with my electrodes between 10 and 1:30 o'clock except from one at 2:30, 12 o'clock being electrode attachment point towards centre of engine.
This way the swirl will sweep the gap sideways and newer hit the backside of an electrode. The 2:30 exception is placed with the gap towards inlet rather than the opposite and is therefore also OK.

Will it be worth the effort ? No idea, but it was fun, and worst case is that it doesn't matter.
Will I be able to tell the difference ? No way, I'm changing a lot of stuff at the same time, and I will not be able to seperate the impact of other new parts and this.

I did by the way find the second ignition coil, I thought was missing. Now it's removed as the new type coil doesn't need this kind of backup.

The cadmium plated engine bay tubing is getting OK with some Autosol polishing, and I've found a supplier of rubber hosing in the sizes needed. He also has the proper fuel injection hose clamps for the smaller hoses.

The fuel tank is out for refurbishing at a radiator/fuel tank specialist. It looked fairly OK, but the darkness of the surface rust in front left corner indicated that it might be leaking slightly there after all.
New closed cell neoprene foam is therefore ordered to replace the smelly stuff.

I guess I'm getting there. Slowly, but steady :)
BR Leo Jensen - Denmark
Image
XJ40 3.2 LHD 1992 (VIN: ...660341). Owned since Nov 9th 2005
XJ-S V12 coupe 1977 (SW53309BW). Owned since April 28th 2016. http://www.xj-s.dk/home/
Citroën 2CV 1975. Owned since Sep 1st 1984
Board member of Jaguar Club of Denmark

pimgmx
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Re: 1977 XJ-S

Postby pimgmx » Mon Feb 20, 2017 11:57 am

Good progress, Leo!!

the daily: 01 S8 http://bit.ly/2kIwP4m
the tractor: 77 LaRo LW https://bit.ly/2Hr9n6y
the eyecatcher: 93 Insignia http://bit.ly/1iGrmsU
the GT: 89 XJS http://bit.ly/1WQGpC5
the project: 95 X306 http://bit.ly/1cW11DN
the pocket rocket: 97 Z3 http://bit.ly/12IfE7B
the ex: 93 3.2 http://bit.ly/14GTNrq

Rory
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Re: 1977 XJ-S

Postby Rory » Sun Mar 12, 2017 7:55 pm

excellent news- fantastic website. :D

rory
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