A couple of weeks back I started my 66 GT Fastback and backed it out of my garage. It stalled about half way out and would not start, just coughed and sputtered. I turned the ignition off and got out. To my dismay, there was a trail of gas from the front of the garage back to where the car was stopped.
I popped the hood and removed the air cleaner. The intake manifold was covered with gas. I ?sopped? the spilled gas up with a couple of old bath towels, hung them out back to ?air out?. (There is a Fire extinguisher in the car and a second one strapped to a leg of my work bench.)
A quick check of the fuel lines and connecting hoses showed no leaks, so it had to be a stuck float. The carburetor is an Autolite 4100.
I removed the air cleaner stud, the 8 screws that hold the top to the body and swung the top to the right side keeping the choke connecting rod in place. It was not a stuck float. It was the secondary float sitting on the bottom of the float bowl because it leaked and was about 3/4 full of gas. This was confirmed by the sloshing sound it made after I removed it. I removed the secondary float from another 4100 I had and did a swap. In 20 minutes I was doing a successful slow speed test run up the street.
Now to the problems.
The original Ford part number for the secondary float is C1AE-9550-B, and the Ford service number is C1AZ-9550-B. This is per the 60-68 Ford Car Parts (aka MPC), Text Section 95.12 page 6.
(The original Ford part number for the primary float is C1AE-9550-A, and the Ford service number is C1AZ-9550-A. This is also per the 60-68 Ford Car Parts (aka MPC), Text Section 95.12 page 6. The primary float for the 4100 carburetor is the same as the 2100 float. It applies to all years Mustangs that used a 2100 carburetor.)
That was documented some 55 odd years ago, and it does not universally apply.
Now it gets messy.
Both the primary (2100 and 4100) and secondary (4100 only) floats are now replaced by C6AZ-9550-C.
If you look the attached drawing, ILL75-095P04-1, an exploded view of the 4100 carburetor, you can see the Ford base number of the floats is 9550 for both primary and secondary. (The drawings are the same for the 60-68 MPC and 75 edition.)
The second picture (as seen from the left side of the carburetor) shows the primary float (labeled FRONT), the secondary float (labeled REAR) and the replacement (labeled REPLACEMENT). Note the offset of the lever arm of the primary to the left (the red line), the offset of the lever arm of the secondary to the right (the red line) and lack of offset in the replacement float (another red line). This confused me at first but remember, Ford had a policy of reducing the inventory of its dealers. If it works, they did it. Ford was not building or servicing Concourse Grade cars.
At a nearby carburetor rebuilding company I got a replacement for the leaky float. It was packaged by and sold under the Walker label, 100-41 (CF299B). It is identical to the Ford rear float right on down to the stamped ridges on the side. The only difference is it has ?AB? stamped on the lever arm.
Jim
