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  •  » Ignition Switch

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    7/29/2020 8:48 AM  #1

    Kristang
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    From: Minneapolis, Mn
    Registered: 4/01/2013
    Posts: 293

    Ignition Switch

    I'm chasing an electrical problem in my 1966 coupe.  I am showing 12.8 volts at the battery (in the trunk) and 12.6 volts at the power distribution lug on the firewall under the dash.  I show a drop of 1.5 volts at the coil.  If I lose 1.2 v at the battery, the MSD ignition box will not work.  At full charge, it fires right up.  So, now that I know I have full voltage at the lug, my next stop is the ignition switch.  I am going to make sure I have full voltage to the switch but if I don't have it coming out of the switch then I know the issue is there.  I read online that the 67-68 ignition switch is rated for higher voltage than the 1965-66 switch.  Is it possible to convert to the 67-68 switch in my car.

    Ideas?

     

    7/29/2020 9:20 AM  #2

    bearcat
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    From: Twin falls, Idaho
    Registered: 4/01/2013
    Posts: 337

    Re: Ignition Switch

    What size wire are you running from the battery to the fuse box? You might have to get a bigger wire due to the distance.

    65 coupe, 351w, c4, power disk brakes, power r&p, vintage air.
     

    7/29/2020 9:40 AM  #3

    Kristang
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    From: Minneapolis, Mn
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    Re: Ignition Switch

    I want to say it's 6 gauge wire but I have to confirm this later.  I didn't have any issues for the first 5 years I had this car finished and then it mysteriously showed up.  I even pitched my ignition box thinking it was the issue but now I doubt it was.

       •Thread Starter
     

    7/29/2020 3:36 PM  #4

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Ignition Switch

    The switches mount in a totally different manner.  Not worth the effort in my book.  Use a relay if the switch is that much a concern. 

    #6 wire seems mighty small for battery current.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    7/29/2020 9:07 PM  #5

    bearcat
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    From: Twin falls, Idaho
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    Re: Ignition Switch

    check all of your grounds first. With the battery in the trunk bigger the better on the feed wire. And if You have it doing double duty like feeding the alternator to the battery also it can cause issues.
    I have my battery in the trunk also, I did what the audio guys call the big 3, big ground big starter Feed and big alternator wire to the battery. with all the modern amenities the 55 year old wiring sometimes can't keep everything fed.

    65 coupe, 351w, c4, power disk brakes, power r&p, vintage air.
     

    7/30/2020 6:58 AM  #6

    wsinsle
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    From: Belle Vernon, PA
    Registered: 4/01/2013
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    Re: Ignition Switch

    I've never heard of one switch verse another rated at how much voltage drop across it. If your losing 10% of your voltage across a switch, replace it, contacts must be getting dirty. Wire size and length will make a bigger difference. Dirty contact through a plug will drop voltage. AS MS said, a relay with shorter wire run would help. Kinda like what they do on head lights.

    Keep in mind when you start cranking your engine the battery voltage will dip at least 2 volts. An older, weaker battery will dip even more. How old is your battery?

    I'll assume you got rid of you pink resistor wire when you went MSD but I goto ask.

    If this forum can't fix it, it isn't broke.
     

    7/30/2020 7:52 AM  #7

    BobE
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    From: White Plains, NY
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    Re: Ignition Switch

    From the MSD Installation Instructions ...
    "The Digital 6A and 6AL will operate on any negative ground, 12 volt electrical system with a distributor. The MSD can be used with 16 volt batteries and can withstand a momentary 24 volts in case of jump starts. The Ignition will deliver full voltage with a supply of 9 - 18 volts"

    I also suggest checking your grounds.  And check the voltage at the 'power distribution lug' while cranking engine to verify the voltage doesn't drop below 9 volts and also check the voltage at the coil while cranking, and with just the ignition switch in the 'on' position.  If you've eliminated the pink resistor wire this voltage should be in the battery voltage volt range.
    If you haven't eliminated the wire from the starter solenoid (which provides full battery voltage to the coil for starting), this voltage will change in the 'start' and the 'run' condition.
    FYI - I have the MSD 6AL ignition, my 65 has the original ignition switch, battery is in the front, I eliminated both the resistor wire and the wire from the starter solenoid and am not having any issues ... yet!

    65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
     

    7/30/2020 2:45 PM  #8

    Kristang
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    From: Minneapolis, Mn
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    Re: Ignition Switch

    MS wrote:

    The switches mount in a totally different manner. Not worth the effort in my book. Use a relay if the switch is that much a concern.

    #6 wire seems mighty small for battery current.

    Good to know, thank you

       •Thread Starter
     

    7/30/2020 2:50 PM  #9

    Kristang
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    From: Minneapolis, Mn
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    Re: Ignition Switch

    BobE wrote:

    From the MSD Installation Instructions ...
    "The Digital 6A and 6AL will operate on any negative ground, 12 volt electrical system with a distributor. The MSD can be used with 16 volt batteries and can withstand a momentary 24 volts in case of jump starts. The Ignition will deliver full voltage with a supply of 9 - 18 volts"

    I also suggest checking your grounds.  And check the voltage at the 'power distribution lug' while cranking engine to verify the voltage doesn't drop below 9 volts and also check the voltage at the coil while cranking, and with just the ignition switch in the 'on' position.  If you've eliminated the pink resistor wire this voltage should be in the battery voltage volt range.
    If you haven't eliminated the wire from the starter solenoid (which provides full battery voltage to the coil for starting), this voltage will change in the 'start' and the 'run' condition.
    FYI - I have the MSD 6AL ignition, my 65 has the original ignition switch, battery is in the front, I eliminated both the resistor wire and the wire from the starter solenoid and am not having any issues ... yet!

    Thanks Bob.  So I have narrowed it down to the wire that runs between the power wire at the lug and the switch.  I am dropping a full volt when testing at the lug and again where the power wire connects to the switch.  I can tell you this new MSD Street Fire ignition box will not fire if voltage drops to 11.2 volts.  If I have a fully charged battery at 12.6 volts, the wire at the switch will be 11.6 and it will start.  If I let the battery drain to 11.2, there is no fire in the hole!

     

       •Thread Starter
     

    7/30/2020 2:55 PM  #10

    Kristang
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    From: Minneapolis, Mn
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    Re: Ignition Switch

    wsinsle wrote:

    I've never heard of one switch verse another rated at how much voltage drop across it. If your losing 10% of your voltage across a switch, replace it, contacts must be getting dirty. Wire size and length will make a bigger difference. Dirty contact through a plug will drop voltage. AS MS said, a relay with shorter wire run would help. Kinda like what they do on head lights.

    Keep in mind when you start cranking your engine the battery voltage will dip at least 2 volts. An older, weaker battery will dip even more. How old is your battery?

    I'll assume you got rid of you pink resistor wire when you went MSD but I goto ask.

    Battery is healthy.  It was new 5 years ago but I did not drive the car during that time but it always had a tender on it.  I have replaced the ignition switch 3 times while I chased this issue.  Every time I replaced it, I also had the charger on the battery so the car would start, until it wouldn't.  I disassembled the switches thinking something would be awry but they were fine.  Yes the pink wire was deleted.  Power is lost between the lug and the switch so I may have a bad wire or my wire guy is thinking he may have used a fusible link wire there and it may be bad?

     

       •Thread Starter
     

    7/30/2020 2:56 PM  #11

    Kristang
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    From: Minneapolis, Mn
    Registered: 4/01/2013
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    Re: Ignition Switch

    bearcat wrote:

    check all of your grounds first. With the battery in the trunk bigger the better on the feed wire. And if You have it doing double duty like feeding the alternator to the battery also it can cause issues.
    I have my battery in the trunk also, I did what the audio guys call the big 3, big ground big starter Feed and big alternator wire to the battery. with all the modern amenities the 55 year old wiring sometimes can't keep everything fed.

    Lots of FAT heavy copper wire in this car!

       •Thread Starter
     

    7/30/2020 4:57 PM  #12

    bearcat
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    From: Twin falls, Idaho
    Registered: 4/01/2013
    Posts: 337

    Re: Ignition Switch

    Lol I have the same fat and happy copper lol I like my dual fans, Maddox box, vintang air and my stereo system. And yes I have a big alternator to power it all. Sounds like you're on the right track.

    Last edited by bearcat (7/30/2020 4:58 PM)

    65 coupe, 351w, c4, power disk brakes, power r&p, vintage air.
     

    8/01/2020 10:10 AM  #13

    BobE
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    From: White Plains, NY
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    Re: Ignition Switch

    Kristang wrote:

    BobE wrote:

    From the MSD Installation Instructions ...
    "The Digital 6A and 6AL will operate on any negative ground, 12 volt electrical system with a distributor. The MSD can be used with 16 volt batteries and can withstand a momentary 24 volts in case of jump starts. The Ignition will deliver full voltage with a supply of 9 - 18 volts"

    I also suggest checking your grounds.  And check the voltage at the 'power distribution lug' while cranking engine to verify the voltage doesn't drop below 9 volts and also check the voltage at the coil while cranking, and with just the ignition switch in the 'on' position.  If you've eliminated the pink resistor wire this voltage should be in the battery voltage volt range.
    If you haven't eliminated the wire from the starter solenoid (which provides full battery voltage to the coil for starting), this voltage will change in the 'start' and the 'run' condition.
    FYI - I have the MSD 6AL ignition, my 65 has the original ignition switch, battery is in the front, I eliminated both the resistor wire and the wire from the starter solenoid and am not having any issues ... yet!

    Thanks Bob.  So I have narrowed it down to the wire that runs between the power wire at the lug and the switch.  I am dropping a full volt when testing at the lug and again where the power wire connects to the switch.  I can tell you this new MSD Street Fire ignition box will not fire if voltage drops to 11.2 volts.  If I have a fully charged battery at 12.6 volts, the wire at the switch will be 11.6 and it will start.  If I let the battery drain to 11.2, there is no fire in the hole!

     

    Are you checking the voltages using the same 'negative' reference point?  If not, the voltage value could change.  Suggest that you verify the body to engine ground wire is clean and making good contact?
    I also suggest checking with MSD regarding the low voltage point of the Street Fire box, 11.2 volts seems high considering that typically a battery has enough power to start the car down in about 9v.
    Also, suggest you check that the power wire in the firewall bulkhead connector is making good contact.
     

    65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
     

    8/01/2020 7:03 PM  #14

    Kristang
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    From: Minneapolis, Mn
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    Re: Ignition Switch

    The culprit is the ignition switch!  That was my first thought and it ends here!  I've replaced that switch 4 times now but at least now I know the voltage in and out was my way to diagnose.  I have been doing some reading on the web and see others having to go through multiple switches before they found a good one.  I mean, what does one expect for $12.00?  Each time I replaced them, the problem went away-temporarily.  I am thinking a relay may be in order because I am not sure the switch is able to handle the voltage demands I am throwing at it.

       •Thread Starter
     

    8/02/2020 7:31 AM  #15

    BobE
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    From: White Plains, NY
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    Re: Ignition Switch

    With the problems you have had, I agree a relay is in order.

    65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
     

    8/03/2020 6:12 PM  #16

    Kristang
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    From: Minneapolis, Mn
    Registered: 4/01/2013
    Posts: 293

    Re: Ignition Switch

    BobE wrote:

    With the problems you have had, I agree a relay is in order.

    UPDATE.  Before moving on to the relay I decided to do a test between 2 brands of ignition switches.  Wow was I surprised.  I went through 4 Standard ignition switches, none of them would hold more than 11v on the output terminal/accessory post.  The voltage varied from 10.2 volts to 11 volts.  I bought a Duralast switch from Auto Zone and it holds a steady 12 volts!!  Since I built my car, I have had a total of 5 Standard brand ignition switches in my car.  I have always used Standard Ignition parts because I thought they were of high quality, much like the Echlin line.  I guess not!  What does a guy expect to get for $13.00?
     

       •Thread Starter
     

    8/03/2020 7:12 PM  #17

    RPM, aka Bearing Bob
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    Re: Ignition Switch

    Kristang wrote:

    BobE wrote:

    With the problems you have had, I agree a relay is in order.

    UPDATE.  Before moving on to the relay I decided to do a test between 2 brands of ignition switches.  Wow was I surprised.  I went through 4 Standard ignition switches, none of them would hold more than 11v on the output terminal/accessory post.  The voltage varied from 10.2 volts to 11 volts.  I bought a Duralast switch from Auto Zone and it holds a steady 12 volts!!  Since I built my car, I have had a total of 5 Standard brand ignition switches in my car.  I have always used Standard Ignition parts because I thought they were of high quality, much like the Echlin line.  I guess not!  What does a guy expect to get for $13.00?
     

    WOW! Thank you Kris. That certainly is polar opposite of everything I've read about Standard Products and auto part store parts.

    Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering, factory AC.
     

    8/03/2020 8:35 PM  #18

    50vert
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    From: QLD Australia
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    Re: Ignition Switch

    I think with Standard, you need to use the Blue Streak line, and with Echlin, the HD line.
    They both have cheaper versions you shouldn't be using.

    Last edited by 50vert (8/03/2020 8:39 PM)

    "Those telephone poles were like a picket fence"
     

    8/03/2020 11:24 PM  #19

    RPM, aka Bearing Bob
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    From: Bakersfield, Ca
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    Re: Ignition Switch

    Ah, good point Barry.

    Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering, factory AC.
     

    8/05/2020 3:28 PM  #20

    Kristang
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    From: Minneapolis, Mn
    Registered: 4/01/2013
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    Re: Ignition Switch

    50vert wrote:

    I think with Standard, you need to use the Blue Streak line, and with Echlin, the HD line.
    They both have cheaper versions you shouldn't be using.

    Just FYI, Standard does not make a Blue Streak replacement ignition switch nor does Echlin make a HD version.
     

       •Thread Starter
     

    8/05/2020 3:34 PM  #21

    50vert
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    Re: Ignition Switch

    Then I'd be speaking to NPD bout their opinion on the best available switch

    "Those telephone poles were like a picket fence"
     

    8/20/2020 9:09 PM  #22

    Kristang
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    From: Minneapolis, Mn
    Registered: 4/01/2013
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    Re: Ignition Switch

    Happy to report, the cheapo Duralast ignition switch is still doing it's job!  I disassembled one of the Standard switches, think I found the problem!  The contacts in the switch were not touching!  Arc marks on both sides.  Also, I finally got my Vintage Air system running, now I can be cool and be cool!
     

       •Thread Starter
     

     

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