Today I pulled apart my carburetors. I plan to clean them up and replace a lot of the parts, essentially do a full re-build. I need to pull them both totally apart in order to send the bodies off to Keith Williams, who has agreed to rebuild the throttle shaft bushings which tend to wear out over time preventing the butterflies from closing completely.
If I weren’t sending off the carb bodies I would only disassemble one at a time so I’d have a working model in front of me making it easier to put them back together. I think I have enough guidance from my manual and the ZTherapy videos to get them back together, though. I will also probably send out some of the parts to be replated in yellow zinc to make the carbs look brand new.
Here is my box of supplies. It includes my hand tools, a couple of cans of Berryman’s B-12 carb cleaner (very good stuff, less than $6 a can at Walmart), lots of paper towels, and a pair of safety glasses and rubber gloves to keep the carb cleaner out of my eyes and off my skin. I set up a work table on two sawhorses using a sheet of plywood that I placed inside a garbage bag so the wood wouldn’t end up soaked in carb cleaner. Also here’ s a shot of one of the carburetors before I started.
First I removed the throttle return spring, which I will replace with new ones from Keith Williams.
I began disassembling the carbs by unscrewing the dome plunger from the top of the dome, making sure I got the plunger gasket that fits around it.
Next I unbolted the four bolts that hold the dome to the body using a #2 Phillips head screwdriver. I pulled off the dome and set it, along with the large suction spring, aside.
Then I slid out the piston and began unbolting the cover from the float chamber.
I pulled off the float assembly and removed the float chamber lid gasket, which I will replace with a new one from Nissan along with all of the other gaskets. Then I set aside the float chamber and went to work on the carb body.
The way the choke works on the carburetor is this: pulling the choke knob inside the car pulls the choke cable that pulls back on an arm that causes the nozzle on the bottom of the carburetor to move up and down. As the nozzle moves up and down on the tapered needle, more or less fuel is allowed into the fuel/air mixture. I next removed the bolt that connected the spring-loaded actuating arm to the nozzle.
The nozzle is connected to the float chamber, which holds the fuel, by a fuel pipe that I had to remove in order to release the nozzle.
The nozzle rides only as high as the idle adjustment mechanism allows it. This is a spring-loaded bolt that goes up and down when you turn it. The bolt is mounted to a sleeve that threads into the carb body; it is through this sleeve that the nozzle rides up and down. I removed the idle adjust bolt by hand and the sleeve using a 19 mm wrench.
Next I began removing the throttle adjustment arm from the body. First I released the spring that returns it to position and then I used a 12 mm socket to remove the mounting bolt.
Then I pulled the assembly off the body. It is composed of many pieces.
I then removed the float chamber from the carb body. I removed the nut from the end of the mounting bolt that feeds through the carb body using a 10 mm socket. Then I pulled the float chamber off the body with the mounting bolt, which threads into the float bowl, intact.
At the bottom of the float chamber is the fuel pipe connection. I removed this using a 12 mm wrench.
Opposite the fuel pipe fitting is a drain bolt. I also used a 12 mm socket to remove it.
Then I removed the bolt that mounts the float chamber to the carb body. I used a 14 mm wrench and a lot of force to get it off.
Next I focused on the float chamber lid assembly, that holds the actual float. The float moves up and down with the fuel level and operations a float nozzle above it that allows more fuel to enter the chamber when necessary and shuts off the fuel supply when the chamber is full. The fuel inlet had two halves which I separated by removing two Phillips head bolts.
With the inlet separated into two pieces, I then removed the banjo bolt (using a 17 mm socket) and the small screen filter inside it.
I then removed the float by sliding out the mounting pin. I removed the float nozzle using a 10 mm socket.
Then on the float side of the body I removed the throttle plate and the nut on the end of the throttle shaft using a 12 mm socket.
From the piston I removed the needle by loosening the set screw on the side and then I made sure to pull out the plastic washer that sits at the bottom of the piston shaft.
Essentially that completed the disassembly of the carburetors into seven pieces (six for the carb not shown). I spent some time cleaning up the aluminum pieces inside and out using the carb cleaner. I used two full cans, but the pieces got fairly clean.