Original 289/Weber Carb Question

[Dan Case]

Originally Posted by 1795

Dan,
Those look like DCOE's to me. Same orientation, body and air horns.
Do you know if they made any modifications to the cold air intake to redirect the air for a side draft carb? On my MGB I fabricated a cold air box that would take air from the side of the radiator and block any air coming through the radiator from the air horns. A hood scoop would not feed side draft carbs very well.
Jim

I have no idea as no pictures of such an installation in a Cobra have turned up in public that I have come across. There are pictures of what look like a painted sheet metal or wooden mock up side draft intake stored in the Petersen archive online.

https://archive.petersen.org/pages/v...it=&ref=860918


(The first down draft “Weber” intake for a Cobra was a mock up made of wood and painted to sort of look like it was an aluminum casting. A picture of the mock up was included in an early Cobra / FIA registration form set. Early on Shelby American created a collection of ‘cold air boxes’ for down draft systems. For whatever reason cold air boxes were rare after mid summer 1963. Most works prepared racers did not use cold air boxes. It also didn’t take long for Shelby American to determine that baffling or completely blocking hood scoop nacelles was real important. )

(LOL, any complete collection set of intakes would require those two wooden mock ups.)

[CompClassics]

It is my understanding that the largest side draft available for the side draft application at the time was a 45 mm, unfortunately this size would not provide the needed performance that was needed for the 260 application, nor was it easily enlarged. Instead of reinventing the wheel SAI changed their manifold configuration to utilize the readily available 45 IDM that Maserati was using on their V8 F1 engines that could easily be enlarged from 45mm to 48mm creating the 48 IDM model. Eventually Weber transitioned from sand cast manufacturing to die-cast manufacturing, supposedly with Fords help to increase production volume. The manufacturing change led to 48 IDM being made obsolete and the 48 IDA the new Weber performance carburetor and it has been for decades now.

It is very interesting to note that Jim Hall never transitioned from 48 IDM to 48 IDA Webers and used them all the way into his Can Am program in 1968.

[xb-60]

I have another picture of the DCOE setup on 260 XHP-260-2 .....




I also have this picture of interest of CSX2534 with DCOE carbs, but I am sure that the addition of the DCOE's is quite a late addition (there's no mention of them being added to 2534 in my edition of the Registry)....




Cheers,
Glen

[peterpjb]

Originally Posted by xb-60

I have another picture of the DCOE setup on 260 XHP-260-2 .....

Attachment 35692


Cheers,
Glen

this picture is part of the first FIA Cobra homologation 79 (8th Oct. 1962)

On page 8 of this homologation these carbs are described as

"Side Draft 58 MM Weber Carburetors"

[Gaz64]

I have yet to see a 58 DCOE carb, so since the photos show DCOE carbs, that list of options must be a misprint.
In the photos, the carb tops and the mounting flange are DCOE, (55,50,48,45,42,40,38mm), versus the upright parallel mounting of DCO 3 carbs that were available as 58mm.
Going by the airhorn (trumpet) size, I'd say 48mm, possibly even 45mm. This is only a 260.

[xb-60]

Gary,

What can be said....except that CS signed it so it must be true....surely?




Cheers
Glen

[Gaz64]

The photos are DCOEs, which at the time, the largest would have been 48mm, 50s and 55s came later.
DCO 3 carbs are completely different in many ways, the mounting flange is the first major difference, and hence the carbs don't interchange.

DCO 3 and DCO 4 are Ferrari 58mm carbs, and very rare.

If Carroll did run DCO 3 58mm carbs, the manifold would've had to have the different flange mounting.

Note on Page 9, where the statement of the carb rarity, and the consequent option of 48 IDA downdraft carbs.

https://historicdb.fia.com/sites/def...9_group_gt.pdf