Carburetor Re-assembly

This afternoon I rebuilt the carbs using the cleaned-up parts, refurbished bodies from Keith Williams, new nozzles from Z-Therapy, and new floats, gaskets, fuel pipes, needles, banjo bolts, and float screens from Nissan.

I was surprised that the carbs went together fairly easily. Basically it was just a matter of reversing the process I had gone through to break them down. I began with the float bowls. The drain and fuel inlet bolts threaded into the bottom of the float bowls. I used a 12 mm socket with hand-pressure to tighten them. I didn’t want to use to much pressure because the bolts were brass and the bowls are aluminum.

I then tightened fuel-supply bolt up using a 10 mm wrench. Next I moved on to the bolt that attaches the float bowl to the carb body.

One end threads into the bowl, through the rubber grommet and the fitting washer. I tightened this down using a 14 mm wrench.

Then I moved on to the lid of the float bowl. I re-used the old float nozzles, because they appear to be in good shape and the new ones I ordered were the wrong size. I tightened the nozzles into the lid, gently using a 10 mm wrench.

Although the old floats were in good shape, I installed my new floats using the original pins. I made sure the floats on each lid sat in similar positions once installed.

Then I placed the new gasket in place and bolted the lids onto the float bowls using the original bolts. I had wanted to replace all of the bolts with shiny yellow zinc ones but they proved to be impossible to find.

I bolted the assembled float bowl to the carb body using the bolt already installed on the bowl. I used a 10 mm socket on the nut on the opposite end of the bolt. Then I attached the idle-adjustment bolts to the bottom of the carb bodies.

First I threaded in the shaft and tightened it using a 19 mm wrench and then I tightened the knob and spring into the shaft, all the way down to the tightest setting.

On the bottom of the idle-adjust knob I cleaned out the nozzle aperture using a couple of Q-Tips. Then I inserted the nozzle.

I attached the new J-shaped fuel pipe first to the nozzle and then to the fuel-outlet on the float bowl.

Then I installed the new jet needles. I used new N-17 needles from Nissan. In order to set the needles, I used the following procedure on each carb:

  1. Loosen the set-screw on the piston.
  2. Loosely install the needle into the piston.
  3. Drop the piston into the body and push it all the way down until the needle bottoms out in the nozzle (holding the nozzle up tight against the body), forcing the needle upwards into the piston.
  4. Remove the piston and tighten down the set-screw to secure the needle in place.

Then I placed the original plastic washers and piston springs back onto the pistons.

And placed the domes over the pistons and bolted them into the bodies using the original bolts.

Next I replaced the dome caps and fit new fuel screens on the banjo bolts.

And I bolted together the fuel inlet piece and bolted it onto the carbs using the banjo bolt, which I tightened using a 17 mm socket.

Lastly I added the bolt that acts as a stop for the throttle shaft. Here is a picture of the reassembled carburetors.

All that remains is to put the arms that mechanically operate the nozzles back together.

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