Hitachi (Type HJG46W Round top SU) Adjustments

1. Unscrew and remove each of the damper rods from the carb depression chamber covers.
2. Remove air cleaner cover.
3. With the finger, raise each of the carb pistons in turn and let it fall under it's 
   own weight. It should rop freely with a "clunk" sound. If it shows any signs of 
   sticking, the depression chamber cover must be removed and the piston extracted 
   and cleaned.
4. Top-off the oil in the dampers to their correct levels using SAE 20 engine oil. 
   Refit the damper rods but do not over tighten them down. They should be hand tight.
5. Make sure that the valve clearances are correct, the ignition timing set propery
   and the engine is tuned properly.
6. Run the car until engine obtains normal operating temperature.
7. Slacken completely the balance screw. Located at top between both carbs on the linkage.
8. Slacken completely the fast idle screws. Located at the top of the intake system near 
   fuel rail. Follow the linkage from the firewall back towards the carbs.
9. Screw up (clockwise) each of the carbs mixture adjustment nuts until they seat,
   then screw the equally between 1/2 and 1 turn.
10. Start engine and turn each of the two throttle speed screws equally until the 
    engine runs evenly at between 600 and 700 rev/min. 
11. A flowmeter is needed. Place it against the front carb intake. Turn the flowmeter 
    setting screw until the upper end of the float is in alignment with the index.
12. Transfer the flowmeter to the rear carb intake without altering the settings.
13. Adjust the throttle speed screw on the rear carb until the flowmeter registers 
    the same as the front carb. Only hold flowmeter in a position for a short period of 
    time, just long enough to take a reading.
14. Remove the flowmeter and tighten down each of the mixture nuts by 1/8 turn at a time
    until the smoothest, fastest idling is obtained.
15. Unscrew each of the throttle speed screws to redure the idling to 600 rev/min.
    Finally make fractional adjustments to throttle screws, using the flowmeter again, 
    adjust until both carbs are in prefect balance.
16. Turn the balance screw so that on visual inspection of the two carbs
    pistons they can be seen to lift at the same time as the trottle is opened.
17. Turn the fast idle screw until the engine is running at a fast idle of 1000 to
    1500 rev/min. Using the flowmeter and if the front and rear carbs differ, correct them
    by turning the balance screw in or out until they are equalized.
18. Release the fast idle screw, rev the engine 2 or 3 times, allow the engine to return 
    to idling and then check the balance of both carbs again with the flowmeter. Any 
    difference in readings must be corrected by repeating the adjustment procedures.
19. Finally, set the fast idle screw so that there is a clearence at its tip of between 
    0.039 to 0.079 in when the balance screw id lightly depressed with a finger.
20. Switch off engine and reinstall air cleaner cover.



Hitachi (Type HMB 46W Flat Top SU) Adjustments

1. Make sure that the valve clearances are correct, the ignition timing set propery
   and the engine is tuned properly.
2. Top-off the oil in the dampers to their correct levels using SAE 20 engine oil. 
3. Run the the car until the engine is at normal temperature. 
4. Unscrew the balance adjusting screw and the fast idle screw until they both are
   well clear of their stops.
5. Turn the slow-running adjustment screw until the engine is running at 650 rev/min 
   (700 of automatic trans) 
6. Turn the mixture adjusting screw in both directions but with in the limitations of the 
   limiter cap, until the engine speed reaches its highest point. If the adjustment 
   procedure exceeds 1 to 2 minutes, the engine should be revved to clear the inlet manifold.
7. Reduce the idling speed by unscrewing the slow-running adjustment screw.
8. Screw in the fast idle adjustment screw until the engine is running at 1400 RPM.
   Use a flowmeter against the air intake of the front carb and turn the meter setting 
   screw until the upper end of the float is in alignment with the meter index.
9. Now place the flowmeter next to the intake of the rear carb and by turning the 
   balance adjustment screw, set the rear carb air intake volume to match the front carb.
10. Unscrew the fast idle screw until the engine resumes is normal idling speed
    and check is return to satisfactory idling by revving the engine 2 to 3 times. 
    The fast idle screw should be set finally so the gap is 0.78 in between its tip 
    and actuating lever. Should any difficulty while making adjustments, check the linkage. 
    I slight amount of free movement in the auxiliary and main throttle shafts which 
    corresponds with the clearence between the throttle shaft end stops.
11. With engine at operating temperature, and the mixture and slow-running speed 
    correctly set, check adjustment of the throttle closure dashpot (Automatic trans)
12. Set engine to 2300 and 2500 rpm. The button on the dashpot should just be in contact 
    with the lever attached to the throttle linkage. Adjust the postion of the dashpot 
    if necessary to provide this setting.
13. Now set the engine to 3000 rpm and realease the accelerator quickly. The time it 
    takes for the engine speed to reduce to 1000 rpm should not be more that 5 seconds. 
    Any wide variation form this indicates a worn out dashpot and must be replaced 
    or repaired.