Weber 48 ida synchrometer adjustment

[hendrix427]

Originally Posted by Eljaro

there is no specific setting. The vacuum generated depends on the engine size, camshaft profile, valve size and choke size. The important thing is to have all 8 throats tha same. Sometimes you may find that one carb gives different vacuum reading on the two throats. I have had to do some throttle shaft twisting to correct that.

I agree, that has always been my experience. I used to tune many cars with webers and when someone brought a car into my shop with tuning problems, I would always start at ground zero. Plugs, wires, points, coil, timing, etc. But even before those, I would start with compression and even better, a leak down test. When you have a engine with each cylinder having their own carb, any cylinder that has different compression characteristics can effect the performance. A leak down test combined with the compression test will prove to be informative. The leak down test can pin point problems with rings and even specific valves. As any weber specialist can attest, they are (especially IDA's) are very sensitive to tune. I would then pull them off the engine and very carefully inspect the throttle plates, bores, and shafts. Leaks around the throttle shaft bushings can be very difficult to fine tune and sync the carbs. When they are off the engine is also the best time to align and equalize all the throttle plates. Large bore engines are more forgiving than the smaller bores as far as tuning, at least that has been my experience.