Burtzy wrote:
The Japanese learned the hard way. I owned a Datsun 2000 roadster. And those twin SU carbs were almost impossible to tune. I had a British mechanic who could do it by feel only. When his hand was sufficiently sucked and stuck to the draft side of one, that was in tune. When he couldn't get either hand out from my engine, it was perfect...or so he said. I had to drive around town with him running alongside. He was pretty spry. Okay, that last part was imaginary.
There’s actually a very useful device to balance multiple carburetors (of any type) that measures airflow called a UniSyn. Mine is 50 years old, but they’re still made.