So what is the answer?
Really,
I think the answer is you do nothing different.
There is no difference between EI and magnetos as far as start procedures, IMHO, with some caveats, in general. To the pilot of a factory plane you turn the key. Many experimentals have separate ignition and start switches, so there is some switch selection choices depending on your set-up.
The stuff about priming, pulling props and throttle stuff is extraneous to the bottom line.
EI should make starting easier. The down side is the electrical power requirement. Magneto's use no outside power (usually). That is the big diff.
All the EI systems I know of: Light Speed, Emag and Electroair, all go to zero degree timing advance during start, which is the advance you must/should have to safely start. You just have to turn the EI on and crank. Once started turn the standard mechanical magneto on. Done!
The EI's I know of, need battery power to get started and continue to run. The exception is the "P-mag" EI, which will continue to run after starting, with out battery power, but it needs juice to get going like all EI's, as far as I know. (Some magnetos use a "vibrator" or "Shower Of Sparks" to get started, which does require battery power. Typical magnetos used on the Lycs we install in RV's don't use shower of spark starting. We have an impulse couple magneto, which is a mechanical method to get a hotter retarded spark for start.)
(Technical content warning! Impulse magnetos have extra features for starting, retarding advance and giving more spark during start only. Most engines have one impulse magneto, the one that goes CLACK! when you pull the engine though. Once started the impulse magneto goes back to being like a regular magneto. With a key ignition switch, the non-impulse magneto is automatically cut out during start. If you tried to start with the non-impulse magneto, you could get big kick-backs because the timing is still at 25 BTDC, or it just won't start. Impulse magnetos do all their start magic mechanically with springs and flyweights. EI do their magic with timing with electronics and sensing RPM and/or MAP.)
If you have
one EI and one impulse magneto, you can start with either. However most use the EI to start and using both during start is probably not a good idea, IMHO. Most EI manufacturer's suggest you start on the EI and leave the magneto off. The EI has more spark power and should make starting easier. If you have a dead battery, no electrical power of any kind you could use the impulse magneto to get started. This means a hand prop start, no thanks. I'll hand prop a C65 or C85 on a Cub, but not a high compression bigger displacement Lyc. Just call me chicken. I'm personally afraid of hand prop larger engines. I just avoid it. Some times EI can miss fire during start with low voltage. If that is the case you could use the magneto to get going.
A single EI is usually paired with the impulse magneto. It's an
odd ball combo to keep the non-impulse magneto with an EI, but there is nothing stopping you from doing it. If you do this, definitely leave the magneto off for start. Use the EI. Starting with a non impulse magneto can/will cause bad kick-backs, which break things. On the plus side, a non-impulse magnetos are simpler, probably more reliable and lighter than their impulse magneto cousins. The mechanical parts of the "impulse" can bugger up sometimes. The draw back is at times, starting with an EI is NOT desirable, so keep the impulse magneto. (see next par)
There are
starting issues with some EI's. EI can miss fire when the voltage gets too low during start. The starter draws the voltage down and the EI fires erratically, which can cause kick backs or difficult starts. This might be a good reason to use the regular impulse magneto if you have one, verse the EI, if you are having this issue. The voltage problem is less likely to happen with a good strong battery and a starter that uses less power. Permanent magnet starters tend be the lower cost units and work OK, but they are also power hogs, which can aggravate the EI starting voltage issue. The new top of the line Skytec starter has much much lower power needs than their original PM unit, which they still sell. The more efficient lower draw starters keeps the voltage up and avoids or minimizes low voltage issues with EI.
If you have
two EI, than I guess starting with both ON is the way to go. Or I suppose leaving one off saves some power for cranking the starter. Which one? Top/bottom, left right? It does not matter, but try it, see if there is a difference.
If you have
two EI's with a dead battery, you're out of luck. Besides you should NEVER fly with a dead battery you jump or hand prop. It's best to spend 45 minutes and give the battery at least a good 75% partial charge with a 10 amp charger before flying. Using you alternator alone to charge a totally dead battery is a good way to fry the alternator, in my opinion. One observation. a dead battery demands much more power to charge over a longer period after starting. With extra drain charging the battery, added to the normal load, the alternator can overheat. Usually a strong battery recovers fully within minutes after starting and never demands as much as a dead battery.
