Mag RPM drop with electronic ign

[mcattell]

I have the Light Speed Plasma II on the right mag and a standard Slick mag on the left. During run-up I'm getting a higher than usual RPM drop on the Slick mag. In reading the Light Speed manual I see this is to be expected because with both selected on the key switch the RPM would be higher than with two standard mags. Therefore the RPM drop with the Slick would appear to be higher than if you had two standard mags. So my questions is, what kind of RPM drop are others getting with their Slick mag with the same setup?

With only the electronic ignition selected at run-up the RPM drop is barely noticeable. Very impressive.

[db1yg]

Eci 0360 with PIII on right--Slick on left.

1600 rpm/full rich

Mag off line -- 10-20 rpm (or less) drop

EI off line 60-70- rpm drop.

Cheers,

db

[Radomir]

I had the same setup as Dave and had exact same behavior.. 10-20rpm on EI and typically 70rpm drop on mag.

[scsmith]

I have a light speed plasma II on the left, slick mag on the right.
Mag off, I get no drop at all at 1900, full rich.
EI off, I get 40-60 drop.

The timing of the light speed at run-up conditions is almost 40 degrees btdc, and that flame front has burned a long way before the mag even fires at 25 degrees, so you would not expect to get much drop at all by turning off the mag.

If you are getting much of any drop with the mag off, verify the timing on your light speed.

[Chino Tom]

Run-up at 1800 rpm,

Mag off, 10 -20 rpm drop

EI off, 100-120 rpm drop

Key switch, YO-360-A1A

[N208ET]

Prop-stop

what was your mag drop tonight

[elippse]

This brings up an interesting modification. What if you were to make a clutch that could go between the mag and the drive so that after checking it you could "put it in neutral" to save wear and tear on it until it was needed.
I have dual Plasma 1s with the interconnect so that if you switch one off the other advances about 5 degrees to restore power. It's interesting when you do a check that when you turn one off, the rpm drops about 70, then after a short delay for an internal time-constant, comes back almost to the same rpm!

[Gsuit]

Superior XP-360 (IO360)
Plasma II on top plugs
Slick Mag (Impulse) on the left and bottom plugs

Run-up 1800 RPM:
Mag OFF - 20-30 drop
Elec Ignition OFF - 100-120 drop

[jimbo]

I have a TMXO-320 17 hours on engine
160 HP. Carbureted
Slick mag on L
EMag on R. (P model 114 running A curve) With NGK Iridium auto plugs suggested by EMag and gapped at 0.030

Run up 1700 RPM. Full Rich. Elev 960
Mag offline EMag online. drop 90
EMag offline Mag online. drop 40

I would think I should have a lesser drop with the EMag online (after all isn't the EMag spark is supposed to be a higher intensity and offer some advance spark at that speed). Checked my switch wiring and the P leads are routed and labeled correctly.

Can someone explain why the RPM drop is more when EMag is online?

Jim

[Bevan]

Jim,

Next time do your run up as lean as it will run smooth, then check the mags.

Bevan