Hi .1972 240z. Standard SU type carbs. I noticed I can turn the mixture right in on the front carb and it starts to faulter. I do the same on the rear carb and very little change. Took the air cleaner off and placed my hand over the front carb inlet and heaps of suction. On the rear carb very little suction. Placed a vacuum tester, or balancer at each carb throat and the rear carb is very low on vacuum even at a very fast idle. The engine runs well and pulls well. Any ideas.:stupid:

Are you changing the carb sync haphazardly or is this during the sync process? If the carbs are out of sync they will display a difference in vacuum (that is what the sync tool checks).

Assuming that the carbs are well balanced and there are no vacuum leaks, I'd check the valve clearance. A compression check could be in order as well.

Thanks for the reply Gary.

The carbs were out of sync. Its been 10 years since I fiddled

with them and had forgotten what I was doing:stupid: Old age

you know!!!!All solved now, cheers.