Modification Suggestions Please!

Hi All!

For the longest time, I was planning on keeping my 1977 XJ-S as original as possible, because it just seemed like the right thing to do with only 50K on the clock, it seemed a good candidate.

Then came the flood. The flood ruined the interior of the car (along with almost every other car in my driveway) as the water came up above the center console.
Well, the car runs again; (largely) Fine with a new battery and a couple taps on the starting relay.

So now it’s time to do something interesting. I’d like to make this car VERY fun to drive, aesthetically pleasing and possibly even suitable tor a longer trip.

This brings me to my question-

What are your suggestions to make this car more comfortable, reliable and fun to use?
I’m not quite at the point of tearing the engine down and re-boring the cylinders and such, I like to keep myself to smaller, weekend projects.
Additionally, I live near NYC and traffic can be… Heavy at times, one is concerned with overheating

Before the flood, in the past two years I have:
Rebuilt all brake calipers and master cylinder.
Replaced all 4 Shocks
Replaced the Ignition with a better system (see my write-up)
Replaced fuel pump
Replaced Fuel Pressure regulators
Cleaned all injectors
Rebuilt cooling system
Replaced alternator (With a Bosch AL9345X) and pulley to allow it to work at speed due to RPM difference)
Rebuilt wiper motor
Replaced Auxiliary air valve
Many other things, hoses, etc
replaced headlights with Better, brighter bulbs (and appropriate wiring and relay for such)
New tires
New Fuel tank
All of these things seemed to have survived.

On my current to do list:
Rebuild power steering pump and rack (something is leaking), Parts on order, rebuild to original-ish (better bushings and such)
Eliminate the air injection system.
Add an oil catch can to reduce the intake sludge issue
Build a new intake to pull cooler air from outside
Replace all relays with modern, not Lucas relays
Replace engine mounts
Remove EGR system

On my prospect list:

Replace transmission with a manual T-5 transmissions look interesting, though I already know and like the Getrag shift patterns)

Replace power steering pump with an electric power steering pump (used Volvo seem to be popular)

** When replacing power steering pump, I will need to do something about the water pump, as they’re on the same belt

Replace both fans with an electric setup

Add a second alternator in place of the air pump or the steering pump to support all of these things.

Rebuild the air conditioning system to R134A (then maybe the girlfriend will be willing to get in the car, one day)

Electric, redundant water pumps with a time out feature after turning off the engine or at a certain temperature.

Replace interior- not sure where I want to go with this one, though eliminating the rear seat is VERY tempting. There’s a part of me that wants a parquet floor (I would build thin panels that get placed on the floor, of course)
I’m also thinking of using termoform plastic to make new door panels and cover them in a pleasant material, such as cork.

Repaint the car (not sure what I want to do here either, but it desperately needs it.

New stereo, speakers.

What other suggestions do you have? Do you have any comments on my ideas? Have you done it?

I don’t need or want the car to stand out (more than it already does) from the outside.

Looking forward to some suggestions!


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Very ambitious Zack…!
Would be fun to see what you end up doing.

All worthwhile.

Just keep in mind that if you change the square metal relays (Bosch), the have protective diodes inside and each in a different configuration.

Wouldn’t 120A suffice?

Personal choice… but I think the easiest and probably nicest would be to find the original ones, or recover the ones you have.

Why not? will give you plenty of extra space for stuff and the audio installation.

Now that would be interesting!

Would cork stand the test of time and dirt?
I would go leather.

Do the Napoli and Bernett mods on the climate control, details in the Book.
Invest in sound proofing, makes a big difference for road noise, feel and of course for the sound system.
I would also invest in a set of nice wheels, they really have a big impact on the look of the XJS.


It sounds like very challenging project. Prior to improvements and mods being done, I suggest to find suitable equipment and allow the entire car to drain few garden butts of water that’s still trapped in between fabricated/welded components. All you need to is three things - made in exact sequence below:

  1. Position the car vertically, with rear facing the sky for a couple of days
  2. Position the car vertically, with front facing the sky for a couple of days
  3. Position the car horizontally, with wheels facing the sky for a couple of days

Obviously, sunny weather without single rain is a must…

There is an alternative method o placing the car in the oven with forced circulation for a couple of days but I tried this one with poor effect on trapped water.

I was thinking that dipping the XJS in the pit with silica gel could make the perfect scenario, but all the silica beads from inside mus be removed later on with vacuum cleaner…

If you don’t have a time or equipment to perform what’s above - I strongly recommend to assemble what’s left and sell it to the next happy XJS owner, which will fight the outbreak of ginger goo - inside out.

Power Steering: You could consider a full electric unit as was welded into the column of this XJS:

Maybe make the undertray too.

I’ve used cork as an interior material - in my case as a glued in replacement for the failed and - at the time - unavailable headliner board. It did quiet the car. It’s a good material but on the floor surfaces and inside the doors you might want to consider using some traditional sound deadening materials like dynamat.

The interior looks nice with synthetic suede surfaces such as Alcantara/Novasuede. Maybe take a look at the Japanese inspired Blue/Copper one-off Ferrari Roma.

Re the water pump, it would be interesting to use a CWA400 & a Techomotive controller for that, maybe in place of where the PS pump was (but packaging will be… difficult.)

Using an X300 or X308 electric heat water pump would be interesting, although packaging again would be a challenge.

Since it’s a cruiser, instead of a 5 speed (which has nice defined packaged paths to get to) a 6speed auto could be considered, and there are controllers for those - but that would take some engineering. There is a supplier for those, but it’s very expensive.

The Ole Mobeck EFI system, while expensive, makes for a nice full EFI management system replacement.

~Paul K.

If you’re looking for more sportiness, this is what i did which awakened my car dramatically (I have V12 w/ TH400)

  1. Adjustable vacuum modulator for transmission which gave me better upshifting and downshifting.
  2. B&M shift kit, gave me firmer shifts.
  3. Opened up air intakes to 3". Gave me nice loud roar at full throttle
  4. Full new stainless steel exhaust system from downpipes to tips. Deleting mid-mufflers gave me more sound and power. Rear mufflers gave me low end roar without sounding too loud. And it looks sweet.
  5. Poly bushings on steering rack
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I just hate to see someone in pain. I have a 1992 model in my building that starts and runs, but the Teeves braking system does not work. It is red, has some clear-coat fading, the interior is decent in bisquit and it has good tires. You would be miles ahead with another car, and decent ones can be had for next to nothing. Think this through before doing anything else.

Thank you for the notes!

Good to remember on the relays.

Cork fabrics and material should actually hold up as well as leather under most circumstances. Part of the draw is aesthetics and part is price and consistency across fabrics.

I also want to play with the seat bolsters a little, which could result in a re-do or two. Perhaps patterning in fabric before leather is my way.


Actually, I did briefly consider the “external combustion” method.

It works by covering the whole car in it’s own juices (gasoline) then starting a brief (yet very exciting) chemical reaction with the aid of a single, long cigar match. My research says that this method is highly effective for removing the ruined carpet and any water.

Now, that article is VERY interesting. I’m already adding aluminum sheets to my shopping list to make some aerodynamic underpans.

The cork isn’t all surfaces and certainly not the floor…though cork flooring is a thing.

It’s an aesthetic choice. I really like the interior (seat shape and refinement) offered here: GUCCI

Though the color is lost on me.

Noted on transmissions, the manual is about fun more than anything, I know it’s a cruiser, but the occasional spirited jaunt to the grocery is what makes life worth living.

Much appreciated with the water pump notes and all else.

I’ll be re-reading that fuel efficiency article a few times.


Thank you Greg, noted.
I’ve played with the trans shifting before, I did replace the modulator, but I haven’t played with any of the kits.
The air box modification looks very interesting and a good way to go.

I found your post on it and it looks like you used the original air box, am I correct?
Do you think more could have been gained with a different airbox? I ask as I’m thinking about removing the factory altogether and creating an intake with better linear flow across the throttle.

Noted on the exhaust. I’ll probably have to do something about these factory down pipes as they have CAT’s built in.

Rack bushings and rebuild kits on the way!


Ahh, I considered something like this, but then I wouldn’t have a highly tunable pre-HE engine to play with, would I?

Plus, I’d feel bad ripping apart a car that isn’t at least kind of broken anyway.

Let’s see what it’s like once I really dig in, but I do love to polish a turd.


So I believe the air boxes work fine as is. My mod was a bit backwoods, but people see it and think it looks pro enough. I cut out the original horns so there was just a hole, made the hole bigger, and bought some plastic electrical ABS I ‘think’ 2 1/2" or 3", can’t remember. I used a bunch of JB Weld to join it. I then tried my best to sand down the JB weld at least on the outside. I also bought an air trumpet and JB-welded that to the end. I then painted it all black.

One gain that can definitely be had is putting on bigger throttle bodies, AJ6 Engineering in the UK sells them. But you’ll have to have your ECU adjusted for them. I didn’t do that.

Yes, I had the CATS built into the downpipes too. But being in WA state, they got rid of smog checks a few years ago. And even if they were still here, the car is over 25 years old. So I just chose to go with no CATS. Mine were destroyed anyways, so they needed replacing, an expensive choice. Yes, my car will be illegal in places like California, oh well. If you need to keep the CATS, you can still remove the mid mufflers and somehow pipe the back of CATs to the OverAxle pipes.

Poly rack bushings make a world of difference, the car handles much twitchier. But you also feel a bit more vibration through the steering wheel over bumps and such. Worth it IMO.

Thank you. That’s very helpful.

I’m curious about the throttle bodies, though I see where you’re at with not wanting to re-map the engine. It sounds like a serious pain.

I’m in the same boat with the smog thing, New Jersey got rid of the checks a few years back for 25+ vehicles when their own plow trucks stopped passing the inspections. Luckily, I have no intention on going to California. I’ll look at rebuilding the exhaust.



Not so much as moving to California, but if you ever want to sell, no Californians (nor a few other states?) could buy without changing the exhaust system. Personally, I’m not bothered.

Here is a link, definitely worth reading. He even talks about simple and expensive modifications.
Roger Bywater runs it, amazing guy who used to work on the V12s for Jaguar. But he’s quite close to retirement.

Let’s hope @JamesLove chimes in!

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I’ve seen that car. I’m also dubious on the colors. I can tell you that suede works extremely well as an accent on the A, B, and C pillars as well as the headliner (because I did that to my car) … and as a replacment for the felt below the instrument cluster.

I do like the 2 tone contrasting leather/suede transition in the center console covering. I’ll keep note of that. I’m not so sure about the fully alcantara/suede covered dash now that I’ve seen it done (poorly I think) on the Gucci car.

A period-correct restomod in the Cyan Racing P1800 Volvo Volvo P1800 Cyan wins Restomod Of The Year by GQ Magazine | Cyan Racing or the Vilner 250CE Vilner - Mercedes-Benz 250 CE would be a really fun challenge.

~Paul K.

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Pull the 6 banger. repace wit an LT1 or an LS. electric fan and pump works well in my lump.

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Thanks for pointing those out. I like the aesthetics on the Volvo project. particularly the seats, though I’m not sure how comfortable those are. Additionally, the fabric use is really nice looking.

Funny enough, those P1800’s are shockingly similar to the early XJ-S as it’s also a D-Jectronic car. As I recall, they even have the same injectors.


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Aha: it’s a “Volvo.”


Only the roof pillars, handbrake and wipers survive from the donor car, whose new chassis is enveloped in carbon-fibre body panels.

knock knock Mr. Love

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