Spitfire Ignition Conversion

[Dennis Parker]

I have a 1990 5.7L King Cobra with the Cone Clutch and Spitfire Ignition , It has performed flawlessly, and I have a new ECM in a box as a spare but have never needed it, I know parts are scarce. I can run the boat all day and no problem till I shut it off and it won't start again until cool, crank sensor failing and can't find one. Want to convert to Electronic Distributor and have ordered a kit. I have seen wiring instructions that wire the interrupter switch to the distributor and I assume it will shift normally according to the "Distributor Kit Supplier" but someone else said I must wire in an overstroke shift assist module or else it's dangerous and can shift erratically and could do damage.

Can anyone shed light on this?

 

[Bondo]

Ayuh,.... Welcome Aboard,.... I don't do OMCs, much less the infamous King Cobras, But,....

With Merc's, the Bravo don't use a shift switch, Because it's a cone-clutch drive,....

Does yer current set-up use a shift switch,..??

 

[Lou C]

I didn't think these used an esa but for some reason they are included on these models...
You could use the Delco ESt and see if you can get an ESA module from CDI electronics that would work with it. Speak to one of their tech guys...

 

[Dennis Parker]

yes, my setup has a shift interrupt switch hooked to the mechanical shift I ordered a conversion kit. Delco EST distributor coil etc and it
appears that the shift interrupt gets wired right into the EST distributor. I should receive it this weekend. That's when the fun will begin

 

[Dennis Parker]

OMC Spitfire to Delco EST ignition Conversion

1991, 5,7 Litre, King Cobra, Cone Clutch. Purchased a Delco EST kit to replace Spitfire Ignition. Set my #1 cyl to 0 degrees at TDC and installed
Distributor which had no markings so started on the cap with #1 being the post the rotor was pointing to and continuing the firing order clockwise. My wiring diagram is identical to one posted in a forum here in 2011 and has been helpful in dealing with each wire from the module connector. I removed the crank sensor and disconnected the knock sensor. The shift interrupt has a white and black wire and I know the white will go to the distributor and I believe the black stays as it is. Can anyone confirm the black reins as is?

I removed the 12.5 volt circuit breaker and the two purple wires I know provide the power to the coil. I tested the purple wires for 12 volts and it appears to be good. Someone suggested that there may be a resistor wire in line to the ignition switch, and if not removed would damage the distributor. Anyone know if OMC Spitfire Ignition used a resistor wire?

Thanks Dennis

 

[HT32BSX115]

The entire purpose of resistor wire with a regular coil is the same as a any other regular ignition system using a coil + "ballast" resistor.

Regular running places a series resistor in the DC power connection. During cranking, when battery voltage can be fairly low but still sufficient to turn the engine quick enough to start it, the available battery voltage may not be sufficient to produce a hot enough spark to start the engine.

So, a lower voltage coil (6v) is used with a series (voltage dropping resistor) AKA "Ballast" resistor (or resistor wire)

During cranking, when turning the "key" to the start position that series resistor is switched-out ("shorted across") or bypassed while cranking applying available battery voltage to the coil to produce a hot enough spark to ensure starting.

You could use most 6v coils with 12v but because the coil primary winding current would be high (double) they would run much hotter and many would eventually fail.

The more modern electronic systems will operate from 8 to around 24v and still produce adequate spark.

The Delco EST doesn't use or need a resistor. If you suspect resistor wire in your system you need to check and locate it so you can remove it........................... the following FAQ outlines a procedure.

http://www.ebasicpower.com/faq/delcoestwiring.htm

Cheers,

Rick

Let me also add, if the original ignition system is removed or disconnected, you cannot check for resistor wire by simply measuring voltage if that primary wire is not connected to something drawing current.

It will still show supply voltage (the volt meter doesn't draw enough current through the resistor to produce much of a voltage drop)

In that event, you must place some sort of "load" on the IGN power wire
(a light bulb works great if it draws 4 or 5 amps etc .......tail-light, stop-light , even a small headlamp etc)

 

[Dennis Parker]

Thanks for your comments. Much appreciated. I determined that I do indeed have 12 volts, and no resistor wire. After installing the new Delco EST distributor and wiring the shift interrupt to the distributor as instructed, the engine runs beautifully and shifts perfectly as before.

Bye Bye Spitfire Ignition!!!!!!!