Good Parts highly recommends the STE Synchrometer for synchronizing all multiple carburetor systems. These precision instruments are designed to measure the flow directly on the air intake of the carburetor with less air restriction than an air filter. The sensitivity of indication is very high on the lower end of the scale to ensure precise adjustment at idle RPM. The internal vane provides an easy-to-read indication from 1 to 30 kg/h.
While a single instrument is sufficient, the use of one per carburetor is helpful. The airflow of each carburetor can constantly be observed until the tune-up is completed.