kill switch w/alternator questions

[daytona kid]

On my 440 street/strip charger I have a kill switch on my tail panel which kills the battery connection, but as I knew already the alternator keeps the motor running. I think I've heard if I disconnect the wires to the alternator the motor will then quit when the kill switch is turned off. My questions are-> #1 Will that work, and pass tech/safety inspect? #2 Will the motor still run ok for a few passes? #3 Will it hurt anything? #4 Which wires do I disconnect., Can I simply unplug the quick connect blue and green wires or do I have to "unbolt" the big black and purple wires also?.. I'm running a stock electronic ignition and a yellow optima batt. Also my kill switch is breaking the negative/ground side of the battery connection, which I don't think makes any big difference.. All and or any info appreciated..

 

[67dart/cuda]

On my 440 street/strip charger I have a kill switch on my tail panel which kills the battery connection, but as I knew already the alternator keeps the motor running. I think I've heard if I disconnect the wires to the alternator the motor will then quit when the kill switch is turned off. My questions are-> #1 Will that work, and pass tech/safety inspect? #2 Will the motor still run ok for a few passes? #3 Will it hurt anything? #4 Which wires do I disconnect., Can I simply unplug the quick connect blue and green wires or do I have to "unbolt" the big black and purple wires also?.. I'm running a stock electronic ignition and a yellow optima batt. Also my kill switch is breaking the negative/ground side of the battery connection, which I don't think makes any big difference.. All and or any info appreciated..

View attachment 956747

To be legal for NHRA you need to have the cutoff on the Positive side of the battery. For my set up I used a 4 pole battery cut off switch. I am switching the Positive side of the battery and the signal wire to my ignition box.

 

[bearman]

You maybe able to put a toggle switch on the dash to cut off alt when you race. Then turn it back on after your done with your pass. The alt will be free floating on the pass then. How much hp you save not sure.

 

[66Satellite47]

I ran a big wire from the stud on the alt back to the cutoff switch in (from bat) and another big wire from cutoff out (power to electrical panel). So power from alt is interrupted along with battery power when cutoff is in off position. Then in an emergency the cutoff kills power to the whole car.

 

[bobtile]

Like this

 

[66Satellite47]

bobtile's diagram works for a normal wiring scheme. Mine is different because I have a second wire that is parallel to the wire to the starter , but feeds the panel feeding my ignition & fuel pump & spares for fan & water pump..

 

[64HEMI330SEDAN]

I put a diode inline with the field wire. the diode only lets current flow one direction. so installing it the correct way is important. I also have a single field alternator.

 

[Badvert65]

I use one of the 4 pole cut off switches. The two large studs were for the battery positive line. The two small studs were wired up to supply a ground for a relay. That relay would be on with the cut out switch on, and off with the switch off. This relay supplies power to the voltage regulator/alternator. I have been to tracks that have you start the car and test to verify that the engine dies when the switch is cut off.

 

[6PKRTSE]

Anyone ever have any issues from the tech inspectors about where your switch is located? I have had an official tell me he didn't like where mine is. I put a piece of masking tape on the bumper labeled "jerk off" for the strip and peel the tape back off for the street.

 

[Badvert65]

Well, I believe the rule book says it has to be PUSH off.
Jus sayin...

 

[dvw]

Well, I believe the rule book says it has to be PUSH off.
Jus sayin...

It makes no mention of switch direction. T 4 pole switch is the simplest method. Turn the field circuit off with the 2nd set of contacts. Or run a dedicated circuit from the alternator output to the positive post of the battery.
Doug

 

[HEMI-ITIS]

My brick was kickin my ***!! Wasn't sure if it were the battery or the alternator,,,I will spare you all the bullshit but my 20 year old kill switch was the issue!! Now she spins like a teenager with a bottle of wine!

 

[Badvert65]

It's in the General Regulations, 8.4

8:4 MASTER CUTOFF


Mandatory when battery is relocated, or as outlined in Class

Requirements. An electrical power cutoff switch (one only) must

be installed on the rearmost part of each vehicle and be easily

accessible

from outside the car body. This cutoff switch must be

connected to the positive side of the electrical system and must


stop all electrical functions including magneto ignition. The off

position

must be clearly indicated with the word “OFF.” If switch

is “push/pull” type, “push” must be the action for shutting off

the electrical

system, “pull” to turn it on. Any rods or cables

used to activate the switch must be minimum 1/8-inch diameter.

Plastic or keyed switches prohibited. Switches and/or controls

must be located behind rear wheels on rear-engine dragsters.

 

[bobtile]

It's in the General Regulations, 8.4

8:4 MASTER CUTOFF


Mandatory when battery is relocated, or as outlined in Class

Requirements. An electrical power cutoff switch (one only) must

be installed on the rearmost part of each vehicle and be easily

accessible

from outside the car body. This cutoff switch must be

connected to the positive side of the electrical system and must


stop all electrical functions including magneto ignition. The off

position

must be clearly indicated with the word “OFF.” If switch

is “push/pull” type, “push” must be the action for shutting off

the electrical

system, “pull” to turn it on. Any rods or cables

used to activate the switch must be minimum 1/8-inch diameter.

Plastic or keyed switches prohibited. Switches and/or controls

must be located behind rear wheels on rear-engine dragsters.

Not sure why you disagree with my post.
It kills everything and passes nhra tech.

 

[Badvert65]

It's all good. I just copied that from the NHRA rule book. I got pinged in tech once because my switch wasn't marked and wasn't 'Push off'. I was able to fix it at the track (turned the switch upside down and used a piece of tape to label it Push Off).
I figure, whatever makes the tech guys happy is fine by me.

 

[oldkimmer]

I don’t believe u can use a 4 pole switch anymore. Only allowed 1 wire/cable front to rear and 1 rear to front.I used to splice into a field wire and click the toggle switch off when going thru tech. Then back on when on the return road. Kim

 

[dvw]

I don’t believe u can use a 4 pole switch anymore. Only allowed 1 wire/cable front to rear and 1 rear to front.I used to splice into a field wire and click the toggle switch off when going thru tech. Then back on when on the return road. Kim

Where did this come from? Section 8.4 Master Cutoff says nothing about this in the NHRA rule book. Mine is 4 pole. Been teched a bunch.
Doug

 

[451Mopar]

On the Charger, the push/pull rod goes through an existing hole in the bumper where a hitch used to bolt on.
In tech they wanted it marked. So took a sharpie and wrote "PUSH OFF" on the bumper. It passes tech.

 

[66Satellite47]

I don’t believe u can use a 4 pole switch anymore. Only allowed 1 wire/cable front to rear and 1 rear to front.I used to splice into a field wire and click the toggle switch off when going thru tech. Then back on when on the return road. Kim

Kimmer, your method avoids the safety aspect of allowing a safety person to quickly shut down the ALL electrical systems in an emergency situation. You bypass the value of tech inspection.

 

[oldkimmer]

They made me change mine to a 2 post. Told me u can’t have that many live wires running to the back.Car shuts off fine. Everything is dead when switch is flipped off. So it works how they want it. Kim