More Old Photos

I think Lowell might be including non-Jaguars and there are many that use SU's.
Pete

 

I don't think SU ever built a twin choke unit.This was one of the limitations to its further development and use in race cars.I don't know the details but the Webers were a far better design and had a considerable wider selection of jets and throttle sizes .They were also considerably more expensive.The SUs were OK for road use. But even the Solex carbs, similar to the Webbers, never could compete in performance. Ferrari tried them on a few occasions but always went back and stayed with the Webers. To make the SU more competitive there were a selection a modifications that even a novice could do at home. I am sure any British mechanic worth his salt could preform wonders not only on the SUs but also on the stock manifolds. tonga's crew.

 

Hi,

But they did, like this:

https://www.google.fi/imgres?imgurl=http://i304.photobucket.com/albums/nn181/spitnl/sideways/doublesu1.jpg&imgrefurl=http://sideways-technologies.co.uk/forums/index.php/topic/722-double-choke-sus/&h=547&w=757&tbnid=85HWFFynBvp-2M:&docid=PB9wqVtyW1hNnM&ei=YdDpVvaTHKrF6ASy2qDIDg&tbm=isch&ved=0ahUKEwi2yIy_k8bLAhWqIpoKHTItCOkQMwgcKAMwAw

Sorry if the URL is a bit complicated, I'm on an iPad and traveling without a laptop this time.

Not that those were very successful, you are right about Ferrari, and even Jaguar had three dual Webers on the D-types, as well as on some later race prepared E-types. FI was of course the future, but when not thoroughly developed, would not be reliabe enough.

I saw some time ago an XK120 for sale that had three of those strange twin-SU's.
AFAIK they were not from that period, but for late 60's F3, Formula Junior or some other in-line engines.

I agree, the Webers are better, especially for flat out racing.

Cheers,

Pekka T.
Fin.

 

How about this one with SU carbs:
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I know this Cooper! Trips drove it! Yes, it has SUs!!

 

The Jaguar C-type had two SU carbs. Jaguar switched to Webers on the last three cars, the light weight C-types.

Cheers Jim

 

Throttle response is the main advantage of Webers over SU's. Weber has the accelerator pump, so the second the foot goes on the pedal gas spits into the throats, the way water come out of a water pistol, and immediately the mixture enriches, lunging the car forward. With the SU's exactly the opposite happens. This is why Jag and other Brits switched for racing.

john

 

Why does a richer mixture make the car lung forward?

Stoichiometric and all that?

 

Lowell, when the butterflies suddenly open wide, naturally air flow thru the carbs suddenly increases. The Weber's accelerator pump immediately compensates for that sudden increase in air by squirting gas in the venturis. Maybe I used the wrong words, but the car "lunges forward" in the sense that it doesn't hesitate. With the constant vac carbs, like the SU's, when the butterflies suddenly open, air flow increases but because fuel delivery is only passive in the SU, it takes time for that faster air flow to raise the carb pistons and draw more gas out of the jets. So, the response is delayed as you would expect. Sorry for the confusion. Anyway, let's get back to more old pictures.

john

 

I'm more confused. Let's do one thing at a time.

Does this make the mixture richer?

 

The sudden increase in air due to the opening of the throttle butterflies leans the mixture, so additional fuel from the pump jets compensates and returns the mixture (richens) to a usable value. Without accelerator pumps, most engines will have a "lean flat spot" when the throttle is opened quickly.

 

Previously I was trying to slowly explain that SU carbs work
just as well as Webers. They do not need an accelerator pump
because of the damper in the bell which acts effectively as an accelerator pump.
Their actual action is a little difficult to explain.
I just came from a ride in a 120 Jag with two SUs and the
car accelerated like crazy with no hesitation.

Webers are used because they are easier to adjust if the engine
is modified --- SUs need their needle profiles altered, and the
correct profile is harder to attain than just changing the different
jets in Webers which work in different RPM ranges.

 

Lowell: Personally, I agree with you that SU's are VERY responsive. The variable venturi principle does not require an accelerator pump. Where the SU really falls down against the Weber unit is in interior streamlining. The SU will simply not flow as much air for the same bore size (especially at medium throttle openings), thus less power. Also the construction of the SU carb does not fit well with one venturi per cylinder installations. English cars normally used SU's because they were an "English" carburetor, just like Italian cars normally used a Weber carburetor as it was locally manufactured. The SU is a very good carburetor, but it has limits in all-out performance applications.

 

My knowledge of how well SUs work in race cars comes from a friend who vintage races, which he has been doing in many cars for
many years, some cars with Webers, some with SU, some with others. He tells me that he often prefers SU.
Having never raced, I have no first-hand knowledge about this.

 

Yes, confirmed by the mirror installation and a chrome button in front of passenger A-pillar covering the hole for antenna installation.

 

Ok so when did Farrow own this car? Also I have a copy of the pages from the Christie's catelogue and on page 101 is a close up picture of the passenger A pillar and I see no chrome button.The first 20 years of this car are a vertual blank. Was Bruno Ferrari(Italy) or Mr. Slot (USA) the first owner?Anything else you would care to give us.....? Thanks tonga's crew

 

When did Christies sell the car? The hole was welded shut later on, the mirror was likely removed at the same time.

 

If you enter 'Pininfarina' in the search bar, you will find many nice old period photos......


https://revslib.stanford.edu

 

The estimate was $115K to $135K.Sold for $63,130.00 though I am not sure this is correct.See FML. Jan6-March 16, 1996 for sale by Cambia Motor Cars. tonga's crew

 

0279 EU:
Original owner was not Bruno Ferrari in Italy.
Original owner was Bruno Ferrari of Latrobe, Pennsylvania, USA (NOT Italy).
Second owner was a Mr. Stout in USA (not Slot).
Third owner was James W. Farrow of Saratoga, CA/USA.
Later with James Boulware, Ronald Laurie, Brad Hallock (the man behind Ketcham), etc..

Marcel Massini

 

4335 GT. Does anyone know the current whereabouts of this car?
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Thanks Marcel. Latrobe,Italy never smelled right right. I know your rarely tell the whole story but if you have dates of ownership for these owners, that would be nice and any other info you would like to part with. tongas's crew