The 'E' Type Forum

Hello, I am new to the forum and relatively new to my XKE rebuild. I have a S2 2+2 and am in the process of switching to a triple HD8 setup.

I recently acquired a S1 manifold and triple HD8 set, however the carbs do not have chokes, and the bodies above the float chamber are not equipped for them.

Has anybody ever seen a setup without chokes?

Thanks so much.
Adam

There are all sorts if iterations of the SU.
Yours probably came from a Mk2 or Mk10/420S whick use a thermostatic starting carburetor. I have 2 sets of carbs like yours in my shed somewhere.
If you can get whoever sold them to take them back it would probably be easier for you.

That is a probably a Mark X or 420G setup, or just conceivably an XK150S setup, but these are so rare that it can be discounted . These were the only cars to use 3 HD8 carburetters apart from the E type . They are unsuitable in most cases because a. the dashpots are too tall, and b. if the manifold also was Mark X type , it stands up too high at the outer end. The result of this is that the bonnet cannot be closed and will be dented

Hi Adam,

You say you have no chokes; can you elaberate?

The chokes are made up of several parts, leavers etc. and some of these may be missing.
On the bottom of the carbs are there any leavers? is there a cam on the end of the brass spindle that goes through the housing that is screwed onto the bottom of the main body containing the jet?

Not quite sure what you mean by the "bodies above the float chamber"?

The choke mechanism is mainly in the area of the jet housing, apart from the shoe and rod that increases the idle and the leavers themselves.

Paul

If you are looking for chokes in the traditional design, you won't find them on SU's. They don't have a constrictor to the airflow like other chokes, but use an "enrichment" mechanism to increase starting fuel by lowering the jet and allowing more fuel past the jet. If you don't see a choke in the chamber it's because it ain't there.

Hello all. Thanks for the input.

I agree. I think that the triple setup I have is from a 420. The jet housing assembly on the carbs is not equipped with the enrichment device, and so there is no lever mechanism. I believe they were originally set for thermo starting assistance.

I have enough spares to make them XKE comparable, and I have the correct S1 triple manifold.

Now, the dashpots are a little taller on this version, does anybody know if that is a problem for the XKE?

Thanks again for all the help
Adam

As Christopher wrote, you'll find it difficult to close the bonnet without damaging it (or the carbs).

You can buy the dashpots (suction chambers) here if you have deep pockets:

http://sucarb.co.uk/catalogsearch/result/?q=auc+8063

according to the parts manual AUC 8063 suction chamber is complete with piston assembly, but if you are interested it would be best to check.

Paul

With shorter dashpots you'd need shorter dampers and springs and possibly pistons if the steel center is taller. Basically it costs a fortune to convert HD8s to E-soec and I bet you don't have the full spares hardware needed, sorry.

Last time I checked just the jet housing assembly (the bit you need to convert the carbs to manual choke) was over 100 GBP per piece. You need 3 of them, then the cranks and levers which connect the jet and butterfly (3 sets) then the shorter bells, pistons, springs and dampers (x3), then the throttle and choke control linkages and fittings. That would put you north of 1200GBP or so with rebuild kits.

I was looking to convert my Saloon to HD8 with manual choke - this alone was about 350GBP.

All in all, it sounds like the best way forward would be to get rid of the carbs you have, and buy a correct set. Not much more cost, and far better certainty of a good outcome.

For what its worth, I have a pair of 420 HD8 carbs on my 340 which I converted to manual choke a la E-Type, using a mixture of home made parts and Daimler 240 saloon HD6 jet hosing parts;the internals can be used but not the housing (smaller diameter).

I have measured the height of the 420 dash pots as best I could and they were 3 7/8" to the top of the damper cap.

My E-type dash pots are 3 5/8" to the top of the damper and from the top of the damper to the underside of the bonnet is a further 1 1/8". In this instance if I used 420 dash pots I would still have a clearance of around 3/4".

I have no idea whether engine movement would make them hit the bonnet though.

Paul