Hope someone may shed some light on how important this system is , got a 2 litre CU type4 engine , which appears to run fine but have noticed only one pipe from the distributor vacuum unit going to the LH carb is connected, but nothing off the other vacuum unit with the RH carb having a blocked up screw inserted into a hose connector? bit flummoxed should I remedy the problem or leave it , cheers
As said the vac advance only comes from one carb. The other pipe on the advance is the retard vacuum, which would be connected to the balance pipe, the at the back of the engine. They will run with it disconnected, but the timing if done at idle needs to be set at 8 deg before TDC not the published 5 deg after TDC.