Lemans float bowls on Cobra's

[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.