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The Place for Model-A Ford Carburetors

Casting Threads

  • Fuel Line input port, in upper casting, has 1/2-20 UNF (SAE) threads
  • Fuel Screen Assembly, in upper casting, has 1/2-20 UNF (SAE) threads
  • Float Valve, in upper casting, has 1/2-20 UNF (SAE) threads
  • Main Hex bolt hole, in upper casting, has 3/8-24 UNF (SAE) threads
  • Drain Plug hole, in lower casting, has 3/8-24 UNF (SAE) threads
  • Secondary Well hole, in lower casting, has 3/8-24 UNF (SAE) threads
  • Carburetor Mounting holes (2 places), in upper casting, has 5/16-18 UNF (SAE) threads
  • Gas Adjusting Valve (GAV) hole, in lower casting, has 1/8-27 NPT (Pipe) threads. Use caution not to cut threads deeper, as it is a pipe thread.
  • Air Adjust Screw hole, in upper casting, has M5x.75 (Metric) threads
  • Main Jet hole, in lower casting, has M5x.75 (Metric) threads
  • Cap Jet hole, in lower casting, has M5x.75 (Metric) threads
  • Compensator Jet hole, in lower casting, has M5x.75 (Metric) threads
  • Idle Jet hole, in upper casting, has M5x.75 (Metric) threads
  • 5/16-18 and 3/8-24 threads which are stripped can be repaired. See Heli-Coil Thread Repair Kits and Installing Heli-Coils
  • Idle Jet, tapped hole, must provide for taper fit.

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