This is typically performed on a dynamometer – creep up on timing until performance stops increasing – for a starting point, use expert opinions – more is not better with timing. Cranking at “Distr Base Timing” is often OK at about 10 degrees and cannot be changed unless the distributor is also moved to re-sychronize. Idle can often be pretty good at 15-25 degrees (depends on the cam). 1100 and 45kPa can often be similar to the idle timing. Most engines need only ~15 at 1100 RPM WOT, and 29-36 degrees at WOT 3000 RPM. Cruising 45kPa will easily like more than that – 40+ degrees at 3000 RPM is common – but watch out that you’re not too far from the “Distr Base Timing” or there will be arcing under the distributor cap, which can sometimes cause surging if it misfires. The 6000 RPM settings can often just be the same or a little more than the 3000 RPM settings.
You first should have a good idea of what your engine needs for cranking spark advance without kicking back – and set the handheld’s “Distr Base Timing” to that value. Keep in mind that this value is then your minimum spark advance allowed, and that the system cannot advance much more than 30 degrees from this value without causing some arcing under the distributor cap (depending on the rotor and cap dimensions). Start the engine (if it won’t start – be sure you’re getting spark and then move the distributor around to at least get it to start). Hold the RPMs above idle (e.g. 2500 RPMs). Watch the “Spark Advance” in the handheld and use your timing light to see timing move the distributor until they match each other. Lock down the distributor – you’re synched!
There is interpolation – for example, if your settings say 25 deg @ 1100 RPM & 45kPa, 15 deg @ 1100 95kPa, 40 @ 3000 & 45kPa, 31 @ 3000 & 95kPa, but you’re driving at 1800 & 65kPa, the timing will be between all of those values – at about 26.7 degrees.
No! There is no learning for timing control. If your engine experiences knocking, it won’t make any adjustment by itself – you have to do the adjustment with the tables provided. The distributor must also be properly set with a timing light – to synchronize the distributor with the engine and handheld.
Ignition timing control allows the timing to be set to what the user desires with RPM and vacuum, without having to change springs, weights, or vacuum advance settings. It allows the timing with boost to be adjusted to be less than non-boost conditions. If a Power Adder system is used with timing control, the spark advance can be retarded when nitrous is used. There is an idle stability function to improve idle speed control by quickly advancing when the RPMs drop, and retarding when it jumps too high at idle. It allows the cranking spark advance to be lower than the idle spark advance, to keep the engine from kicking back on the starter.