I thought I'd try to contribute a little to the forums by giving an update on my 83 XJS. I'll try to keep this short while providing what I think may be valuable insights to others.

Short version: I bought this car in October 2021 off a guy on Craigslist for $2k cash. In the late 90's a prior owner had swapped in an old Chevy 350 (unfortunately one of the low-powered ones of the early 80s) and a TH350 automatic transmission. The car drove okay but needed several misc things that took months to address (front springs were still original, heater core leaked, and several electrical things).

Then in June or July of 2022 I began paint prep in my garage. Took the car down to bare metal, performed some rust repair, sealed the car with 2k epoxy primer, and did some prep sanding. That part took a year. Never doing that again.

Next, I tackled the engine and transmission. I hate wiring so I didn't want to go the LS route (hate is a weak word). I also hate automatic transmissions. I decided to purchase a 350 crate engine from Blueprint and located a used rebuilt LT1 T56 manual transmission locally. Naturally, Andrew at Jaguar Specialties supplied the engine/trans mounts and a great deal of technical support. One other thing to mention: I'm 34 so I've never had the pleasure of a carbureted car. Couldn't resist. I just think they're so cool. (Plus, I have an MR2 Turbo making a de-tuned 340 rwhp, so trying to make the XJS truly fast didn't make any sense.)

I've put about 370 miles on the fresh engine and so far, so good. No full throttle pulls yet as I'm still breaking in the new clutch, but the car responds well. Much more fun to drive than it used to be.

I also just rebuilt the IRS (one of the halfshaft u-joints was failing, the outer fulcrums had some play, and the rear rotors didn't look so great). I installed a 3.54 XJS diff while I was at it. The LT1's gearing combined with the 2.88 diff was just ridiculous. Even now I'm at 1500 rpms @ 70 mph in 6th gear.

Here are the main regrets I have in the hopes they may help someone. Below that are some misc pictures of the project.

Regrets

• Regarding the paint & body, I should have just sanded down areas of the car that had chipping paint, laid down some epoxy primer, and had the car vinyl wrapped (wraps have come a long way and look as good as paint unless it's a show car job). Yes, that means I wouldn't have discovered some of the small rusty areas, but none of them were structural, and I doubt they would've gotten much worse (I never drive in the rain and I only use waterless car wash sprays). The downside of my approach wasn't just time and effort, but the results. When you remove paint, you remove metal. I did not consider this carefully enough, and the unfortunate result is that there are some waves in then car. The good news is you can only spot them if you're looking from the correct angle and you're conscious of them.
  
• Regarding the engine: I should've gone LS, but not for the reasons you may expect. The BP 350 crate engine has been great, no complaints there. Dyno'd at the BP factory @ 353 hp/404 tq. An LS1 makes 345 hp (or 375 starting around 2001) and about 350 tq by comparison. The reason I should've gone LS is two-fold: 1) The oil pain that came on the BP 350 is deeper than the OEM pan, so it wouldn't clear the steering rack. Out came the engine, replaced the pan, and put it back in. Only cost me 2-3 days, but not fun. 2) Because the BP 350 is a performance engine, it has a performance intake. Taller intake + Carburetor = no hood clearance. It wasn't an issue with the old 350 that was in there because that silly thing came out of a truck so it had a very low profile intake not designed for performance. I tried everything I could to get the hood to clear but it was a no-go. This is the part that will make the purists cringe the most, and I wasn't a fan of doing this either. Cut a hole in the hood and attached a GT350 steel hood scoop (hey, at least it's somewhat period-correct). I'll likely color-match the scoop to the car in the near future (it came black).

Future plans include wheels and reupholstering (or replacing) the two front seats and the driver interior door panel.

I make one last appeal to the purists: this car had a poor future when I bought it. Had this been a very nice original example, I probably would've retained the V12. The odometer reads 138,500 but hasn't worked since I bought it, so there's no telling how many miles it actually has. Interestingly though - according to Carfax, this car has been here in Houston since it was sold brand new. For how many miles it has, that's pretty cool in my book.

Old engine:




New engine:



Cringe if you want, but it's functional.


Trying to cope.


At least it's pretty low profile. DB5's had a scoop too, so there's that...







Cut up some aluminum and attached an old emblem to fill in the gap fore of the shifter.

 

Sorry you had to cut the hood. Edelbrock sells a very low profile intake manifold and a low profile top hat for the air intake to fit the Chevy 350.
I installed one in my XJS a few years ago. No problems with clearance for the hood.

350 with low profile intake and tophat in my XJS

 

Good to know. I tried some drop base filter setups and those weren’t enough. At least it’s just a hood!

 

I think the bonnet (hood) looks fine, good for you. The entire point of having a fun car is to have fun doing it up as well as driving it. In fact, this is the first body mod I have ever seen on an XJS that does not make the car look worse than stock. I bet the car goes like a rocket too. And everyone knows that God intended us to use carburettors and we have sinfully and erroneously strayed into electronics! Look where it has got us, fridges that last 4 years, diagnostic readers to find out why a car is not working, 1000 dollar headlights, hunchbacked teenagers with vision unadjusted beyond two feet...
Once it is painted, then I honestly think it will look like something the factory did.

 

I suppose I’m a purist, but in my view you’ve found the perfect project car. I can’t see anyone objecting to improving a poorly executed (and likely on the cheap) prior “lump”.

I also believe over time you will be glad you did the paint and bodywork over a wrap. Enjoy it.

 

Thanks for the kind comments. I will say the scoop has grown on me a little, partially because of the view from the driver’s seat:


I love seeing the top of the air filter.

 

The scoop is cool. Not as cool as the manual trans, but plenty cool.



How did you handle the clutch pedal?

 

Andrew (Jaguar Specialties) sells the manual pedal box. My only advice would be to use a banjo bolt fitting instead of your typical AN fitting. I had to go through several different fittings until I found the perfect one.