SU carbs

[David Kemp]

Over the years I have heard of people putting SU'S or Webers onto Jupiters, has any one real knowledge of this? I ask as the Zenith used by Jowett was fine for Bradfords , but seems primitive for Jupiters.
Also how common are down draft SU's ? Or are they put onto a elbow manifold?

[Jack]

Hi David,

Worth talking to Keith C on this, who I am sure will post. His car had Webbers from memory (but I can't be sure) which seem to work.

Peter Tribble has also got different carbs fitted, which I think are SU, however to fit them they have a special adaptor block which looked to be quite a bit of engineering - it certainly wasn't a straight bolt on job. I have a picture that Peter sent to me by e-mail, I would need to confirm with him that he is ok for me to share.

Both are downdraft and do not have an elbow manifold.

Edit - also worth getting Keith's input as he has just gone through about 50 carbs we had to work out which are Javelin, Jupiter, Bradford or something else entirely, and there are differences between them, including the width of the throat. Keith should be able to confirm.

Jack.

[Jack]

Pictures from Peter show the adaptor blocks and the carbs fitted to his car:



They do work, having seen Peter's car in action, whether they are better or worse than the Zenith I don't know.

Jack.

[Forumadmin]

Hi David,
I am busy at the moment, but try searching for Carb, carburettor, Zenith, DeLorto, Dellorto, Weber etc on JowettTalk and on jowett.net and jowett.org there is tons of info on there even in the pre 2006 JowettTalk. You can also do the same on JowettGallery which will reveal info on the Dellorto.

[Jack]

Topically, the Jupiter at the NEC show this weekend had Webber carbs fitted, so I took a picture. The carb looked the same as the ones I have seen on Bedford CF and Land Rovers in the past, so should be readily available and parts easy to source. Given that one of these quite happily (when it actually worked) ran my 2.3 litre Bedford engine, dragging a motorhome behind it, I am quite confident that two of them on the Jupiter engine will be more than good enough for the job.



The carb used did not have a choke, instead the choke was fitted to the accelerator to provide a few revs while the engine warms up. It does however have a diaphragm on the side which allows the driver to pump the accelerator to squirt fuel into the engine for easy starting.

I was told in discussion that Ed Nankivell had also fitted Webbers to one of his Jupiters, so might also be worth asking to confirm which model he used and any problems he encountered.

Interesting alternative idea, has anyone tried boring out the centre of a Zenith carb, perhaps those in competition who are looking for anywhere they can gain more fuel/air without falling foul of scrutineers? Even with the air filter removed it would be a seriously committed judge to pick up on the throat of the carb being a couple of mm larger than standard, and tiny increases in diameter should theoretically increase the amount of air that can get down there quite significantly.

Jack.

[Greg Jackson]

I have Derlorto brother has webers ,both Jupiters run a lot better with them

[Andrew Henshall]

Off the top of my head, we also have Jupiters running in Australia fitted with the following alternative carbies:

Solex - downdraft (Mike Allfrey)
(Can't find a photo of Mike's installation at the moment)

Weber - downdraft (Neil Hood)

JCCA Rally 2006 016_s.jpg

SU - downdraft (Maurie Stone)

DSC00948_s.jpg

All reported to run better than they did with the original Zeniths!

[David Kemp]

Off carbs a bit, is the blue on Maurie Stones A Jowett colour? If so what colour I want to paint mine this blue. Saw one 35 years ago like that, it has left an impression deep in my mind.

[Andrew Henshall]

Hi David, indeed significantly off topic, but Maurie Stone's Jupiter is currently painted a light blue metallic colour. It does actually look quite striking, although not particularly traditional. Don't know if it is the same as the original Jowett colour called "turquoise blue (metallic)" refer to Tim Kelly's thread "Jowett Colours".

Maurie's Jupiter was originally BRG, and has been repainted several times over the years. Why don't you give Maurie a call and ask him if he has the colour code? His phone number is in the JCCA Register (2008).

Cheers,
Andrew

[Chris Spencer]

Its not Jowett Turquoise blue metallic, from eye I would say it is very close to a period Jaguar colour 'Opalescent silver blue metallic' - link below details various models in the colour
https://www.google.co.uk/search?q=jagua ... d=0CCAQsAQ

[David Kemp]

I have always described the colour to people as early Jaguar metallic blue. Back on carbs

anyone tried Nikki progressive carbs? these were once common. I know manifold would be a bit of work , but possibly worth it.

[Andrew Henshall]

I had a Nikki progressive downdraft carby on a Japanese engine years ago (Isuzu Bellett sedan). They are a relatively simple carb that works well, and has twin barrels, fixed diameter venturis, no solenoids, no diaphrams, manual choke, and drives pretty well, as long as you are happy to drive on one barrel at part throttle, and have the second (larger) barrel open only at large throttle openings. I seem to recall the primary was a 21 mm choke and the secondary had a 27 mm bore.

Interestingly, the Isuzu Bellett GT coupe that replaced my sedan had twin sidedraft carbies; Japanese carbies manufactured by Hitachi that were a copy of an SU. In fact the only common parts between the Hitachi and an SU were the needles. The Hitachis worked well although they needed regular balancing like SUs - I guess they copied that feature too!

Andrew

[Edmund Nankivell]

I have 32IMPE Webers on one of my Jupiters, and 32 ICH on the other Jupiter. They work excellently well. It was in New Zealand that the 32IMPE Webers were first used on Jupiters. You can either make 30mm to 32mm conical adaptors or open the inlet port up to 32mm which is what I have on my Jupiters.

[David Kemp]

Thanks this is all very positive. Has any one anything negative to say regards recording a Jupiter? I am not worried about originality, more about drive ability. I am also thinking of fuel injection, there are kits now that use your original carbs as throttle bodies. But some how I think carbs are easier to work on.

[Edmund Nankivell]

I find these Weber carbs, available from Carburettor Hospital I think they call themselves, work brilliantly. Instant starting, no need for choke. Absolutely no flat spot. Much much lower fuel consumption. Better flexibility at high and low revs, can pull away in 2nd gear on the flat and on slight uphill gradients. Jowett would have been amazed. So sad they were in Zenith's pocket. I think Becquart had Webers fitted to his competition Farina Jupiter. Dellorto's work the same.