Can you set timing with a vacuum gauge? Use a vacuum gauge to adjust idle mixture and use a timing light to adjust timing.
How do you adjust ignition timing?
Does vacuum advance add to total timing?
This improves throttle response and makes the engine more efficient. It also helps the engine run cooler. The vacuum advance provides this benefit BEFORE the Mechanical Advance provides Total Timing. A vacuum advance unit can add up to 15 degrees of advance.
Does advancing timing raise idle?
Our experience shows that connecting the vacuum advance to a manifold vacuum source will add timing at idle and improve idle quality in gear with an automatic transmission.
What should timing be at idle with vacuum advance?
This can be checked with the engine running at idle with a timing light. Make sure the vacuum advance connection is removed, and now rev the engine up to around 2,500 to 2,800 rpm. Ideally, the timing now should be somewhere around 34 to 36 degrees to total advance.