After countless hours trying to get satisfactory performance from the AED on my RHD XJ6 series 2 with HIF 7 carbs I've finally given up and installed the Lucas manual conversion. When I first bought the car the AED was running far too rich, would not turn off, fouled the plugs and caused bad misfire and backfire. After dismantling and adjusting the unit no end of times I concluded the only way to have the engine running well (when warmed up) was to wind the mixture needle more or less right down. This was sort of ok but made the engine quite hard to start from cold. Despite ambient temperatures rising in the UK recently, for whatever reason it became harder to start, putting a strain on the starter motor and electrics.
Therefore I decided to fit the conversion I'd bought a few months back. It came with limited installation instructions and nothing about cable routing etc. I couldn't find a single installation video online so this is what I did if it helps anyone:

Not necessary, but bought a used AED online (complete but similar issues) so I'd keep the original intact.
Remove the AED top section and gasket which is no longer needed.
Remove the original air spring and fit new spring supplied with the kit together with the original top spring collet only.
Remove the bottom diaphragm and spring and replace with new parts in kit.
Check float bowl float and adjust if flooding or too little fuel in bowl
Check square headed fuel mixture needle and adjust to around 8mm above body of AED
Fit unit to AED without gasket
Pull out rubber grommet from bulkhead on drivers side which bonnet (hood) cables run through. It has potential for four cables. Behind this is an awkward angled inset steel plate to the facing right hand side of the bonnet cable route as looking through the grommet hole from the engine bay. There is nowhere to thread the choke cable without drilling a new hole. Direct drilling is almost impossible as the bit will slip, so:
Mark a drilling point with a sharp centre punch and heavy hammer.
Pierce the steel with a thin sharp instrument. The steel plate is strong and will not distort.
Drill out to slightly larger diameter than the cable using a long drill bit
Push a thin arc welding rod or similar through the hole from the engine bay in to the cabin.
Remove locking nut from the rear of the new choke cable knob, install mounting bracket provided and replace nut.
Using good electrical tape attach the choke cable inner wire and welding rod together.
Gently feed through and pull rod and cable into the engine bay.
Route the cable through the grommet, bonnet catch bracket, under the stay bar and on to the choke unit cable clamp leaving some slack for carrying out other works . Carefully measure required cable length and cut outer cable sheath to length and then inner cable. For my RHD car I had to remove 32 inches but LHD would be much less.
Mark position of choke knob clamp in cabin to the lower side section of the dashboard close to the bonnet pull lever. The dashboard side is padded vinyl but has a strong steel plate behind for self rapping screws provided.
Adjust and clamp cable to choke unit as appropriate.
Having used the choke from cold it starts the car well but out of the box I have needed to nurse the throttle for a few minutes before it will tick over well. Once warm it runs fine. If anyone has any fine tuning advice of the unit I'd be glad to hear.
** The provided instructions say you have to tune the main carbs with the choke inlet blanked off before fitting the unit. I did not find this at all necessary.




.

 

Rob,
very good pictures you have there, you won't get many responses as the "die hards" won't like the setup...i'm a bit different i have the same model and had the same flooding problem from when i bought the car, i did something similar but different, i removed the AED and created butterfly flaps the same as down draft carbs, i have HS8 Su's, fitted the flaps at the front intake, choke cable i fitted where the dash light dimmer switch is, didn't need it as i replaced all dash lights wit led's, so now the choke system works on restricting air flow the same effect as a down draft carb, fitted an adjustable fast idle solenoid on the manifold to control the throttle shaft.........in saying all that, as for your Q? about tuning do you have a link to download instructions, pictures are good but don't show how to.....instructions say to tune the main carbs with choke off is just an assurance they are tuned correctly as in making sure the deck height of the main jets are set correctly & throttle arms in sync......

 

my first car was a 1969 MG-B and I got used to the pull cable choke. It was very effective and never gave me any trouble.

In 2004 I purchased a 1965 Jaguar S type and it has the AED. I hated the automatic choke inmediately.

Since then, I have been dreaming of a cable choke retrofit. Makes a lot of sense and always wondered if an MG-B choke could be adapted tp eliminate that AED. I am not ready to do it but in the future I sure would like to.

 

Jose, my mechanic fitted a choke from a triumph……works great.

 

Unfortunately I have HIF 7 carbs so options are limited. The conversion I fitted does start the car well from cold but it's certainly not a start and drive off solution as I've found it won't run with the choke even slightly pulled out (other than initial firing up) so you need patience. Maybe there's a reason for this within remains of the AED ? Adjusting the choke cams doesn't seem to help either. When the car is running manifold depression keeps the jet needle down and only the air valve moves up and down. Not sure if that's right ? When the choke is pulled out with the engine running (cold or hot) I can hear a rush of air and the engine stalls, however all of this is better than a flooded engine, fouled plugs, bore wash etc. Here's a link to instructions: https://www.scparts.co.uk/pdf/362960.pdf

 

Probably similar hardware as the MG ?
​​​​​​​

 

Rob,
does the unit have a fast idle system or just choke?

 

Tom,
The unit relies on remains of the AED for enrichment and fast idle, which is basically everything except the AED bi metal strips and bakelite cover. This means the AED jet needle, float level etc. need to be set up properly and in good order, but I'm not sure the choke would work immediately as it should do if attached to an AED with factory settings. The only adjustments you can make are the AED jet needle for fuel enrichment and two cams on the choke unit. The air valve on the AED is not adjustable, but a stronger return spring is fitted from the choke unit kit, together with a new diaphragm for the bottom of the AED. My AED has been adjusted previously and in this instance I have had to (by trial and error) adjust the jet needle to what I'd say is a richer setting than standard because too much air comes in from the non-adjustable valve, stalls the engine and doesn't allow for fast idle. I also ground approx. 2mm from the bottom of the fuel enrichment tappet as advised in the instructions, although I'm not sure why this isn't shorter in the first instance. Very much a tuning exercise and you are still at the mercy of the AED which plays a significant part in how the engine runs generally. If you can get the AED jet needle where it needs to be and adjust the cams by trial and error it is actually quite controllable. I've now managed to adjust things so that the engine starts straight away from cold and idles around 900 rpm with the choke around quarter out. It behaves more or less what I would expect from a manual choke on a seventies car however the general running of the engine (warm) isn't quite as good as it could be and I suspect this is still down to the AED. I'm surprised there isn't more info available on the AED choke conversion but will persevere with fine tuning !

 

Rob,
easy way to control the fuel and fast idle would be to fit a fast idle solenoid & fuel shut off valve that where synced together as in the fast idle would activate & the fuel shut off would open together & visa versa, i eliminated my AED completely but fitted a fast idle solenoid, if interested i can supply pics on how it's done

 

Hello XJTOM, I am very interested in your solution bec I tried several possibilities to solve the problems with the AED. All without success. So can you please provide me with details of your solution.

 

Hi, would be best if you emailed me via my website, email on top left of home page, in your email can you give a brief description of what you tried, my solution requires a bit of metal work & soldering or retro fitting.
https://www.jaguar-wiring-schematics.info/index.htm

 

Folks
Stop stuffing around with attempts to make the AED work.
There are manual choke kits available all of which entail putting a choke plate leading into the carburettor.
The majority of carby manufacturers used this system and it worked.
I had a S2 SWB 4.2 and I battled with the AED until I got smart and fitted a proper manual choke kit.
That tamed the beast, and I had no further starting issues in the twenty years I owned it.
It's still working OK according to the current owner.

 

back in the late 1960's I had a twin carb MG-B with a very simple choke cable that started the engine right away.

I wonder if it could be adapted to my 1965 Jaguar S type to eliminate the AED.

 

Easily, it just needs some sort of hinged flat plate to semi-cover the manifold inlet, as here:
https://www.mecholic.com/2018/09/wha...oke-valve.html

A look at the choke arrangement on your petrol strimmer or mower shows the idea. Or swap out the SU carbs for ones with a manually operated needle enrichment device!

 

Bill, that's exactly what i did on my HS8's (home made) choke the air not flood the fuel, still works after 10 years........tom.in Sydney

 

 

That looks like it is the same kit I put on my S2 XJ6.

 

Works great Bill….haven’t had an issue starting cold for last 10 years.