As some of you have read in my other post, I have a '74 XJ6 that I am selling for a friend. I have been threatening to send it to the crusher but now my wife has fallen in love with it so it may get a reprieve after all. Go figure. If I were to keep it, I am not worried about the powertrain side, I will convert to Chevrolet fuel injection and overdrive transmission. I have done a number of swaps with those and am very comfortable with the process. Chevy engine mount kits are very common and available for XJ6 of course.

My biggest concern is the Lucas electrical system. I would have a GM starter and alternator so that would help. What actually goes wrong? Is it wiring? Switches? Connectors? Any idea on reliability on the fan motors and window motors? I can’t find a definitive answer on what really goes wrong with Lucas electrical but I have heard a lot of jokes.

I have done a lot of searching on the various electrical components and found this for 1974 XJ6; it appears to have a lot of electrical components that are hard to find and/or expensive:
Ignition switch-readily available, but expensive
Headlight switch ,not readily available, but I could convert to a GM switch and put it where the original was
Wiper switch, not readily available, but I could convert to a street rod switch on dash or later XJ switch
brake lamp switch is expensive, but I could convert to a GM switch
Turn signal switch are available or I think later can work

I am toying with removing virtually all original wiring and replacing with a street-rod style harness with GXL wire and good connectors where required. I would keep original turn signal, ignition, and HVAC switches as well as power window motors and HVAC motors. I would find a way to use GM headlight, brake light, and wiper switches and motor . I would change to Stewart Warner gauges. I would put a GM fuel tank with in-tank pump where the spare tire was. I would change all marker and turn lamp sockets or at least wiring to common US components. I can’t find anybody else who has done anything like this, but it doesn’t look that hard. I would then have a ’74 XJ6 with modern drivetrain and wiring but it would look very close to original. It would have brand new reliable wiring on almost all of the important parts. I would have a project with my 2 sons. There is no value to kill, I know that already.

Any thoughts on this as a project? Any reason it won't work?

 

The overwhelming majority of the famed "Lucas, prince of darkness" stories can be traced to loose/corroded connections. It wasn't until the 90s that Jaguar began to specify sealed connections. Re-wiring the entire car simply isn't necessary, IMHO. Clean all the grounds and connections, and repair any that need repairing. This will certainly be easier than wholse replacement of wirng harnesses.

Lucas alternators, starters, relays are generally high grade in my experience. The manually operated switches---signals, windows, etc.---usunot so much. Quite often, though, they can be opened up are repaired and you're good to go for another 10-15-20 years. Actually, it's rather satisfying to do so......actually fix something rather than throw it away.

(I'll defend Lucas a bit here. I'll bet money that Lucas would have gladly provided any quality level that Jaguar specified...for a price. But, Jaguar often pinched pennies)

One alternative is to look for Ser III parts to replace Ser II. I think at least some of them are virutally identical but more readily available. Headlight switch, for example.

The some-less-reliable Smiths gauges on a Ser II could proably be directly replaced with the somewhat-more-reliable Veglia gauges from a later Ser III. These are "dime a dozen" pricing ...especially compared to the cost of a full set of brand new Stewart Warners.

Anyhow....

Do what you like but IMHO you're wayyyy "over-repairing". You can have a very reliable electrical system for much less effort and expense than you think.

Cheers
DD

 

Yes !!!

I learned the eccentricity of my XJ wuzza six early on. Headlamp was dark. Easy, replace the seal beam. Been ther, doine that. Nope, still dark!!! Went to connection checking and cleaning!!! Ha, rolled the fuses and cleaned the underside of the fuae box. all back and in order. Left new lamp in place. Old is now a spare.

Window issues. Removing them is a simple. Opening and cleaning not so much but very doable. Only caveat, work over pans both in the car and on the bench. Lots of little screws and switch parts to vanish!!

Starter overhaul is very similar to the Delco's used in GM cars for decades.

Only place I am stymied is in the driver courtesy lamp switch in the door post. it forms the ground leg of the circuit. But, clean, tighten and lube failed. It is worn out of spec. Tripping it horizontaly lights sup the interior. No biggie to me. i know where things are and get in in the dark just fine. Mebbe one day, I'll get a replacement from David Boger.

I am messing with the brake fluid level sensor. Slick little float thing. But, a brass tab is busted. I have another that doesn't sork for another reason. One day, I'll meld them.

Way back when, an early mentor hammered a lesson home. Battery cables have four ends. All four must be clean and tight and lubed to protect them from corrosion. No exceptions!!

Electrical theory: Using the frame or body as the ground leg is asking for trouble. It happens often. A far better way is for each component to be insulated and connected via a hot and a ground wire. Much more reliable. But, cars are not wired that way, so....

Carl