THE INTERNATIONAL JAGUAR 'S'-TYPE REGISTER FORUM

I was browsing on YouTube yesterday and I came across an S type that had been converted to a manual choke using Mk2 Jag sliding controls, I don't know what the carbs are as the engine bay was not opened, I assume that the HD6 carbs with the enrichment carbs fitted cant be converted.

John

1B1257BW

Don't know John is the simple answer but I do not understand why you would want to put a manual choke on. The system we have on the S Type the AED (Automatic Enrichment Device) works perfectly as long as the Otter switch works and the AED adn engine are tuned properly.
As you are aware from my previous posts I recently fitted a cool air pipe to my air filter housing. Since then I have had a problem starting the car especially when hot.
Yesterday I tackled the problem and went back to re-tuning the carbs. I set them as per the Blue book but it still smelt rich. My mate lent me a Colortune kit. If you have not come across one of these before I fully recommend you get one.
The kit has a spark plug with a glass top which you put in place of the first plug. You connect your HT lead to the new plug and start the engine. The glass top allows you to look into the combustion chamber and to see the colour of the spark. Even though I had set the car to factory settings my spark was very yellow which meant is was rich. I reset the mixture screws whilst watching the colour of the spark until it turned blue. Car starts first time every time now hot or cold.

the only reason why I keep wittering on about the choke is that my one is either on or off via an electric switch , she starts first time on the button when cold but it is that area when she is neither hot or cold is the issue whereas a manual choke can be adjusted to the temp cold /warm /hot. Yes I have a colour tune unit and have had it to great success for at least 30 years . From cold After a minute or two she starts to over choke but is too cold to turn the choke off.



John

John,
You need to set up the needle on the AED for your conditions.


I believe it is possible to change to a manual slider control. (You would have to source a slider & suitable Bowden cable)

You would need to change item 58 (Jet Housing Assembly) in this diagram in both carbs so you can manually pull down the jets on their diaphragms. Burlen can provide 58 in a number of configurations.


This arrangement as fitted to the E Type for cable activation.


Note I have never done this but it seems possible. I would talk to Burlen.

JOHN

It should be fairly straightforward to convert a HD6 thermo carburetter to a HD6 none thermo unit, that is straightforward but not necessarily easy.

A reference that might help you is the 1966 P6 Rover TC (Twin Carb) engine which amongst other cars has HD8 none thermo S.U carburetters. I believe the choke parts are identical on the HD6 and HD8 NONE THERMO units. A search on the web should show certainly a few HD8 none thermo units including the Rover TC. I have converted HD8 to none thermo in past years, but I would check with Burlen that choke parts are interchangeable between HD6 and HD8 carburetters, but I rather believe they are.

My notes indicate a HD8 thermo converted to a HD8 none thermo would require the following for each carb and Burlen would confirm if they would fit the HD6:-

AUC 8483 screw
AUC 2451 spring
AUC8655 jet housing
AUC 8962 cam shoe kit and rod

In addition you would need a carburetter rebuild kit, a carburetter choke interlink, a choke cable assembly and a method of blanking off the lower fuel feed from the front carburetter to the AED unit.

Glyn’s image of the S.U carburetter is a thermo version that does not illustrate the none thermo choke parts listed above. Look for a HD non thermo type, which will show the choke and no AED.

I believe SNG Barratt’s were advertising a conversion kit a short while ago, but I would think Burlen would also make up a kit.
Having stated the potential requirement for conversion, I think you should be able to obtain a fairly smooth transition from choke on to choke off, if necessary raising the idle speed as done on the full synchromesh cars. I would guess you are operating at 500 rpm idle speed and you might find it advantageous to raise it in the region of 650 rpm.

Not a conversion I would take lightly.

Choke operating slider mounted on a Mk2.




Replacement for item 58 on your existing carb diagram:

2 X AUC 8654


Then as Norman suggests you need the lever link rod (between the two levers), inner cable clamp for primary lever & carb bracket to clamp outer Bowden cable sheath. (see E Type pic above) Burlen can advise.

You could leave the AED in place for cosmetic reasons deactivated.

Now it just so happens that I have the complete lever, bracket, switch, cable, chrome and escutcheon in my new box of many parts. If you want it John PM me with an offer if not it is going on EBay next week.

They even use a handbrake switch for the light.! Straight out of the parts bin.

BTW this slider choke control was only fitted to 2.4 litre Mk2's with Solex carbs & obviously E Type.

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john