I think I've mentioned it previously, but I have converted my car to EFI. Part of that was using a mass airflow meter to meter the incoming air. I used the air filter box from an XJ40 (or an X300), either will work. I made a small bracket to mount it in the left front wheelarch, ahead of tire. Rubber ducting that I obtained at the junkyard then then runs high, so the ducting clears the tire. Then I used the cast elbow from a Series III XJ6 to make the bend through a hole I cut in the inner fender and then piping goes across the engine and into the cast plenum of the original carbs, which I am using as throttle bodies. Definitely not concours, but it works.

The main reason I did this was to reduce the intake air temperature. The engine bay gets very hot in these cars, I was routinely recording air temperatures of 100°C when I used the original air cleaner. Hot air is bad for both loss of power and it leads to detonation. The engines are already prone to detonation due to the combustion chamber design, so I didn't want to add to the troubles.After I changed to the under fender style air filter I was recording maximum temperatures about 10° above ambient, and at highway cruise only 2-3° above ambient.

I had a look and I don't have any photos of the filter, but it did fit with little effort in front of the tire. There are various lids with different length and sizes of trumpets, I took a shorter one, I think it was from a late XJ40 or early X300, so somewhere in the 1993-97 range.

To make it neater, I probably would have put the filter in the right wheelarch again, and moved the vacuum reservoir. However, that would require doing something different to join to the carbs.

 

One thing you might wish to consider is getting those vapor blasted. It's a misnomer, but its really using a slurry of water and baking soda under pressure. It will clean off all the rust and corrosion and leaves a like new sheen on the aluminum. It's not polished, but makes it look like new.

Some before and after examples are here: http://www.universalcycle.ca/content...apor-Blasting/

 

I did that with my inlet manifolds etc. & then polished the top as Jag did. It leaves a lovely finish.

 

If you can't find anyone to do vapour blasting another option is glass bead blasting.
We used it all the time in aviation maintenance and repair.

 

Inlet manifold "vapour" blasted on my car. Leaves a great finish. Damper threads cleaned after this. Everything was loose at this stage. Pilot build to ensure nothing missing.

 

The rear carb from the setup I got for practice cleaned up amazingly well. It took about three trips of forty minutes through my ultrasound cleaner. Today with all of the parts in hand and some time spent reviewing the various instructions for the "routine service" from the SU shop manual, the front carb service is going well. The prongs on the forked lever were about 3/8 inches instead of the recommended 7/16. Because I am a rookie, I don't know if I should be concerned about how much hard black stuff was in the intake body and in the piston/suction chamber. The ultrasound will clean the float chamber lid and the piston/suction chamber eventually. After the lid was off of the float chamber, blowing through the inlet, increasing incrementally from 3/8ths to 15/32nds, got a seal. I don't know how much upward force the float puts onto the lever, but my lungs will go to about six ounces of pressure per square inch. In any case, the consensus of the posts in this thread is that the overflow problem is the float needle and seat, and that is surely correct due to a lack of seal and the fuel level set too high.
The rear carb intake is very black also. I'll take it apart after I get the front one back together.