Lemans float bowls on Cobra's

[otto]

just wondering where any of the small block car's sold with lemans style float bowls , thanks for any info

[Dan Case]

From my notes file:

Three, as currently known, custom ordered new Cobras finished near the end of production (during 1965) received COBRA high rise aluminum intakes and Holley carburetors originally designed for 1965 MUSTANG GT350s, they were CSX2497, CSX2553, and CSX2555. All three received 1965 MUSTANG GT350 high rise intakes and carburetors AFTER 1965 MUSTANG GT350 production had started. These cars received manual choke knobs and operating cables in the instrument panel to the left of the steering wheel... CSX2497 was to date the only known Stage I Competition Cobra sold new that way.

(Side note. CSX2513, one of the sixteen special competition Cobras with 'cut back' doors was “sold” as a used car to Shelby’s driving school 12/18/64 with a used “Mustang” engine with a high rise intake and 1964½ Ford 427 C4AF-9510-DA revision level A dated 4B4, R-2919 Holley carburetor but that race only car is not in the count above.)

There was another very rare COBRA “high rise” intake manifold not intended for street use that I have found zero evidence that Shelby American ever installed in any new car. I have only seen five of these intakes and have owned two of them. Three of them had been broken and welded up as a repair at some point in time. They are very light weight thin wall castings and they are fragile if any fasteners were over tightened. I have a new old stock one that the original owner of a CSX23xx range car bought over the dealer's counter for his new Cobra but he never installed it. The latest one to come to my attention was dealer installed in a CSX24xx range car and it appears to have never been messed with since that installation but the Holley carburetor was separated from the car just before the current owner bought the car.

All three cars described above 'lost' those factory installed induction systems over time. When the owner of CSX2555 had the engine modified during a restoration he had the 1-4V induction system replaced with a Ford / Holley 2-4V system of the type used on Trans Am Mustangs in 1967 installed and I got the R-3259 carburetor dated 4B5. (The sign off date on the original specifications for the R-3259A was December 2, 1964. Holley had two production runs of them in December 1964 in time for the start of GT350 production. In more modern times a subsequent owner of CSX2555 had car returned to a more day one like configuration. I offered to sell him the car's original carburetor at the cost I paid for it years before. He was not interested. Later I sold the carburetor to the owner of 1965 MUSTANG GT350 SFM5026 which was complete in the old Cobra works at Venice and not the new LAX shop like most 1965 GT350s. Early in 1965 a metering block change occurred and to Holley they became R-3259AAS models. The next change altered timing and rate of opening of the secondaries and became the R-3259-1A. The final model going to Ford was the R-3259-1AAS with a different main body casting as the easy to spot difference.)

The R-3259/R-3259-1 family of carburetors (under Holley revision levels R-3259A, R-3259AAS, R-3259-1A, and R3259-1AAS) can be tuned to work very well in an original Cobra but do poorly if tuned like designed for Mustang chassis. The angles at which engines are installed in chassis are significantly different between Mustangs and Cobras. The short wheel base and stiff suspension of Cobras also affects performance.

[otto]

Dan , thank you very much for the info have some 3259 carb parts from a 65 gt350 clone I was working on and was thinking of installing them on my ERA fia car . after reading your reply it might not be worth the effort to use them
thank you again Bob Peckham

[Dan Case]

Originally Posted by otto

Dan , thank you very much for the info have some 3259 carb parts from a 65 gt350 clone I was working on and was thinking of installing them on my ERA fia car . after reading your reply it might not be worth the effort to use them
thank you again Bob Peckham

You are welcome Bob. The main issue is that the angles engines sit in the chassis are different.

A Holley® R-3259/R-3259-1 carburetor in an original Cobra without tuning development often meant (no particular order):

- Difficult to start cold.


- Might under some highway conditions suffer surging in engine rpm (slight).

- Air Fuel Ratio (AFR) goes very rich (black wet sooty exhaust) on hard cornering, especially on bumpy roads or race tracks, complete with engine stumble.


- AFR goes very rich (black wet sooty exhaust) on hard braking complete with engine stumble or even flooding out.


- Driving up or down a steep slope, especially if the road or track is bumpy, may result in rich mixture stumble.


- Near impossible to restart hot.


- Fuel escaping a fuel bowl out through the auxiliary venturi onto throttle shafts and sometimes out the throttle shafts on the intake manifold after shut down depending on angle to horizon that the car is parked side to side and front to back.


- Objectionably high fuel vapors and their odors in garages after hot shut down, especially if fuel has escaped to the intake manifold during driving (flooding).

When we bought CSX2310 in 1983 I was somewhat disappointed with all the above problems. The second owner of the car had his local Ford-Shelby dealer install a 1-4V “COBRA” induction kit in the late 1960s. For a few years I ran it in the open track event at the Mid-America Shelby Meet in Oklahoma. It was a miserable open track car the first time out in 1984. I started off looking up what Ford specified as the angle of the engine in a 1965 Mustang and then I measured the angle of the engine in the Cobra. I made a 1:1 sketch of the carburetor and some simple X-Y dimensions. A little math and I came up with a starting point for new dry float settings front and rear. From there I did trial and error until I came up with dry float settings that worked and eliminated all the bad manners. It was tedious, one float level change at a time to see what happened. I did all the work on the R-3259-1AAS that the dealer installed for the second owner. Once I got it working very well under all street and road course conditions I did the original carburetor from CSX2555 which was an R-3259A revision level assembly; worked the same.

Over the years since I have set up this family carburetors for friends with original Cobras also. The point is that if you take an assembly specifically designed for one chassis you very well may have to develop new tuning characteristics for a different chassis and or state of engine tune to make pleasure in driving and all around performance high on the fun meter.

[t walgamuth]

"Cobras with 'cut back' doors" ...is this the top rear edge of the door leaned back over the last five inches or so I see in some pics?


On the FIA car there is a large opening in the front edge of the hood. Is that ducted to the radiator to create downforce?

[Dan Case]

Originally Posted by t walgamuth

"Cobras with 'cut back' doors" ...is this the top rear edge of the door leaned back over the last five inches or so I see in some pics?


On the FIA car there is a large opening in the front edge of the hood. Is that ducted to the radiator to create downforce?

There were 16 roadster chassis made with extra large rear wings (a.k.a. rear fenders in the U.S.A.) that were so large the leading side necessitated cutting the door frames back into an arc in the other direction. The door frame were cut, a new reverse curve tube put back, and a similar set of changes to fit the new door frames were made to the door B pillars. 5 of the chassis were completed to comply with "FIA" rules.

Day one they 16 chassis had bonnets (a.k.a. hoods in the U.S.A.) with welded in long forward facing scoops.

The Daytona Coupes got very angled radiators and air ducting up and out in front of the engine.

[t walgamuth]

Originally Posted by Dan Case

There were 16 roadster chassis made with extra large rear wings (a.k.a. rear fenders in the U.S.A.) that were so large the leading side necessitated cutting the door frames back into an arc in the other direction. The door frame were cut, a new reverse curve tube put back, and a similar set of changes to fit the new door frames were made to the door B pillars. 5 of the chassis were completed to comply with "FIA" rules.

Day one they 16 chassis had bonnets (a.k.a. hoods in the U.S.A.) with welded in long forward facing scoops.

The Daytona Coupes got very angled radiators and air ducting up and out in front of the engine.

Thanks Dan! I believe I understand now the reverse curve in the door edge.

I don't understand the answer to my question about the big horizontal opening in the front edge of the hood. Is that not a ducted very angled radiator discharge similar to what is in the Cobra coupe and the contemporary GT40s?

Thanks very much for your very informed posts!

[Dan Case]

Originally Posted by t walgamuth

Thanks Dan!

I don't understand the answer to my question about the big horizontal opening in the front edge of the hood.

Thanks very much for your very informed posts!

You are welcome.

Do you have a picture you can attached to a private message, email, or post here in a gallery on this site? If you have a picture of a car with the feature in question we can exit Bob's carburetor thread.

Dan

[t walgamuth]

I'll look. Actually thought it was in this thread.

[t walgamuth]

Try this pic:

[Ron Scarboro]

There is a picture of a racing cobra with three circular duct holes between the front hood and the nose of the car. Much like the Ferrari 250s of the time.

I have that photo somewhere, but can't find it. Is that what you're referring to?

[LMH]

The vents like in this thread?
Hood vents

Larry

[A-Snake]

Originally Posted by t walgamuth

Thanks Dan! I believe I understand now the reverse curve in the door edge.

I don't understand the answer to my question about the big horizontal opening in the front edge of the hood. Is that not a ducted very angled radiator discharge similar to what is in the Cobra coupe and the contemporary GT40s?

Thanks very much for your very informed posts!

I think you are referring to the bonnet of a Daytona Coupe. See photos in this link.

Most Wicked Shelby Cobra Ever - the Daytona Coupe | MyRideisMe.com

[t walgamuth]

Here is the car I am seeing:

[Dan Case]

Originally Posted by t walgamuth

Here is the car I am seeing:

Not a 1960s Shelby American feature for production street or race roadsters.

[Ron Scarboro]

Interesting pic. The three in the front are what I’m referring to. I’ve seen them on a vintage picture of a racing cobra in the pits, but can’t find it.

[Dan Case]

Originally Posted by Ron Scarboro

Interesting pic. The three in the front are what I’m referring to. I’ve seen them on a vintage picture of a racing cobra in the pits, but can’t find it.

CSX2196 had holes cut in the nose at some point in time. It was the chassis that morphed through cut and try development into the "Flip Top" Cobra powered at one time by an all aluminum 390 FE engine with 4 each 58 mm Weber carburetors. Over time it had all kinds of cut outs in the front of the car but it was an 'experimental' or development type car and not something Ford-Shelby sold new to customers.


https://www.flickr.com/photos/sundudecan/6947266287


Sorry Bob, this thread strayed a long way from GT350 carburetors and factory use in Cobras.

[LMH]

Originally Posted by t walgamuth

Here is the car I am seeing:

Neither of those is an original car. I know the owner of both.
Larry

[t walgamuth]

I understand.

I'd like to talk to the owner of the car on the right. I might want to do that with mine, providing I can find a hood for a reasonable price.