Nissan 100NX N14 silhouetteN14

Carburetor - Inspection and Adjustment (Fast Idle / Vacuum Break)

EF & EC-652prose procedure
Continued from EF & EC-651

Fast Idle

  1. 1
    Warm up engine. Remove automatic choke heater bimetal cover and set fast idle arm on 2nd cam step of fast idle cam.
    Top view of carburetor throttle linkage with an arrow pointing to the 2nd cam step of the fast idle cam. Label: '2nd cam step'.
    SEF615K
  2. 2
    Read engine speed.
    Fast idle speed (at 2nd cam step): 2,200 ± 200 rpm
  3. 3
    If out of specifications, remove carburetor and make fast idle adjustments as follows.
    1. 1)
      Place fast idle arm on 2nd step of fast idle cam.
    2. 2)
      Adjust clearance "A" between primary throttle valve and inner carburetor wall by turning fast idle adjusting screw. Clearance "A": 0.47 ± 0.07 mm (0.0185 ± 0.0028 in)
    Carburetor view showing the fast idle adjusting screw and primary throttle valve, used to adjust clearance 'A'. Labels: 'Primary throttle valve', 'Fast idle adjusting screw'.
    SEF616K
  4. 4
    After adjusting clearance "A", install carburetor on engine and check engine speed.
  5. 5
    Install automatic choke heater bimetal cover.

Vacuum Break

  1. 1
    With engine cold, visually check that choke valve is fully closed.
    Vacuum break diaphragm test setup with a vacuum pump applied. Shows piston rod, choke valve, clearance R1, and instructions to bend tongue to adjust. Labels: 'Vacuum pump', 'Vacuum break diaphragm', 'Apply vacuum 53.3 kPa (533 mbar, 400 mmHg, 15.75 inHg)', 'Bend tongue to adjust', 'Piston rod', 'Tightly contact', 'Push lightly', 'Choke valve', 'R1'.
    SEF009D
  2. 2
    Apply vacuum to vacuum break diaphragm.
  3. 3
    Lightly push piston rod in the direction that closes choke valve and check clearance "R1". If out of specification, adjust "R1" by bending tongue.
    Clearance "R1": 1.31 ± 0.14 mm (0.0516 ± 0.0055 in)
  4. 4
    Lightly push piston rod toward diaphragm and check clearance "R2". If out of specification, recheck and adjust clearance "R1".
    Clearance "R2": 1.84 ± 0.28 mm (0.0724 ± 0.0110 in)
    Vacuum break linkage showing clearance R2 check with vacuum applied. Labels: 'Apply vacuum 53.3 kPa (533 mbar, 400 mmHg, 15.75 inHg)', 'Bend tongue to adjust.', 'Tightly contact', 'Push lightly', 'Choke valve', 'R2'.
    SEF010D
Support our work!

Search Manual

Search pages, specs, and procedures