Mikuni PHH

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Mikuni PHH 40 and PHH 44 sidedraft carburetors are a licensed version of the famous Solex sidedraft carburetor. They may be marked Mikuni, Solex or both. They use the same base flange pattern as Weber DCOE and Dellorto DHLA carburetors. Mikuni was the brand Nissan Competition sold for A-series engines. Mikuni made the PHH series from around 1970 until 1995. A PHH 50 was also made but are too big for regular A-series engines. Mikuni "Solex" is far more popular than Webers in Japan.

• Mikuni recommended fuel pressure is 2.84 - 4.98 psi

• Mikuni calls the idle-mixture screw the "Pilot" screw.

• Carb flange same as DCOE. The air cleaner side bolts are spaced slightly different. Elongating DCOE air cleaner holes lets them fit on the PHH.

• Choke: A most interesting feature of the PHH is that instead of a choke butterfly valve for cold-start enrichment, it using an enriching circuit called a "starter" which rotates to open the starter jet.

• Starter: Yellow circles. Connect choke cable to these.
• Pilot Screws: yellow arrows
• Idle speed screws: Green arrows

• Mikuni PHH Carburetor Service Manual (PDF)

• Size is stamped on the throttle blade

  165 = 1.65 inch (40 mm)

Fuel Pump

Mikuni recommended fuel pressure is 2.84 - 4.98 psi. A stock A14 pump should work fine. They are rated 2.8-3.8 pounds (early A12 was lower pressure).

You can easily test the fuel pump with a vacuum/pressure gauge with engine idling. Then remove hose and see how many CCs come out in 60 seconds. A14 pump at 1000rpm should pump minimum of 1.3 liter.

That A14 rating of 1.3/minute is good for 125 HP engine. That's a pretty hot street motor, not many A14s can do that naturally aspirated. For a racing A14 you'll want a higher volume pump.

So test your pump. It may put out 1.5 liter/minute. Then no worries even on a very hot street A14.

Parts