OT garage question, replacing coil pack with a disty on my boat Options

[malcolm2]

Question for the smartest motor heads I know here on 914world.

My 92 ski nautique has a ford 351, holley 4 barrel and OEM Pro-Tec coil packs. I get ZERO spark. The boys on the boat forum set me up with a D.U.I electronic marine disty and the know-how to use some of the coil pack wiring to run it. 2 wire disty, 12v and tach.

Word is the Davis Disty needs 10.5 volts to spark. I have not tried to start it yet, wanted to get the 10.5 first then set the timing and be done.

OEM wiring is as follows.



they want me to use a wire (P, 3A below) coming off of the 12.5 amp breaker in the btm middle of the photo.

I checked the following.

1. at the BATT voltage with key on = 12.38V, key to start = 11.09V
2. TOP RELAY POST (batt wire) key off or on 12.49. Start 9.7
3. RELAY POST to 12.5 breaker key on 11.5. Start 8.2 ( blue circle, i think)
4. RELAY POST TO NEUTRAL SWTCH key on 0. Start 7.8
3A. P WIRE key on 11.5. Start 8.3 ( this wire comes from the 12.5 breaker )

Does all this seem normal? Is my 23 old relay or starter draggin down the voltage.

my relay is upside down... batt comes in on top... otherwise the same.

[malcolm2]

bumpppp.

Is there an expected voltage drop thru this type of solenoid?

[r_towle]

Keyed 12vdc is the way to get it working and eliminate any unnecessary electronics in a wet zone of the boat.

From the key, run a new wire to the coil and be done with it.
You should have some wiring,running back from the key to the old ignition system that delivers 12vdc to the old system.
That old system would step it down to the lower voltage for the coil packs, but you should have it coming off the ignition switch already.

My suggestion is keep it as simple as possible, it will get wet, and you need to have a simple and fast way to diagnose it, and a relay is not the answer.

[malcolm2]

No coil no points no condenser it's all built in. 2 wires. 1 is keyed 12 volts 1 is the tach. I replaced the solenoid today. I gained 1 lost volt. When i disconnect the starter wire and put he VOM on it and turn the key i have 11.5v. I am feeling the starter is dragging it down. 23 year old starter.

[malcolm2]

Another thing i found… with the new solenoid. I actually got a voltage jump without the old starter connected. Not much but maybe a 1/2 volt increase on my expected hot wire to the disty. Starter is at the shop for rebuild. He confirmed that i should get an increase thru the relay.