Finally hooked up a vacuum gauge the other day. At tickover the vac is low and needle sits in the red, a slight increase in revs and it just about goes into the green. The red says late ignition timing. So can I advance the ignition timing on the cam belt? I did fit a new cambelt when I built the engine up, maybe I have not lined the marks up 100% though I thought I had. Could this produce this problem? Any help would be much appreciated.