Starting circuit wiring

Electrical and Ignition

  1. prorac1

    prorac1 Well-Known Member

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    We're looking for some routing and sizing advice for our starting circuit wiring.

    Car is a 1963 valiant.

    Dashboard and all wiring harness came from a 1965.

    Small block engine.

    Here's my plan thus far.

    Battery cable from battery to starter.

    Feed 6-8 guage from large starter lug to large starter relay lug.

    Does this routing and sizing sound correct?

    We're also planing on bypassing the amp guage, running two dedicated 8-10 guage feeds through the firewall from the starter relay. And wiring the alternator directly to the starter relay.

    We're also adding a dual field alternator/regulator, and an electronic ignition. But that's another conversation for another day. Lol.

    Thank you again for your help. Thanks. Eric and Jason
     
  2. 67Dart273

    67Dart273 Well-Known Member

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    If battery is in stock location then parts store "off the shelf" cables are OK size. This is especially true if you are going to a mini-starter which draws less current

    If the battery cable goes from battery to starter relay, and then down to the large starter lug then the lower cable needs to be larger than 6. Use 4. Parts stores sell "starter" cables (eyelet to eyelet) which should be fine

    You should not need TWO no8's through the firewall if you are eliminating the ammeter. A pair of 10 or a single 8 is way more than enough. REmember, if you run the alterntor to the starter relay, you have ELIMINATED the heavy charging current that used to go through the bulkhead (ammeter).

    Be sure to fuse link or breaker the alternator wire, if the alternator shorts, there will be no protection.
     
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    • prorac1

      prorac1 Well-Known Member

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      Should I run from the battery directly to the starter with the battery cable?

      Or should I run from the battery to the relay, and than down to the starter lug.

      My wiring schematics don't specify and I can't remember.

      Thank you so much for the help Del.

      Thanks. Eric
       
    • prorac1

      prorac1 Well-Known Member

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      My reasoning for running two feed wires through the firewall to the interior is to use one as the factory did. Feeding the "welded splice" to feed the ignition switch, fuse block, and headlight switch.

      The other hot wire will be used to feed an auxiliary fuse block for future accessories.

      I believe the alternator is 80 amps.

      What size charge wire should I run from the alternator to the starter relay?

      And what size fuseable link should I use to protect the circuit from alternator over charge?

      Thanks again. Eric L
       
    • supertruck

      supertruck Retired Old Fart stock car racer FABO Gold Member

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      One of the guys on here, I believe Crackedback, sells a great harness to use for the alternator to relay upgrade. Used it on my build and it's first class.
       
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      • 67Dart273

        67Dart273 Well-Known Member

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        Fuse links for me are a problem, some of them are not specifically rated. IF the alternator is NOT a "one wire" a no8 would be plenty large. If it is, I'd run a 6

        You need a fuse link that will handle alternator output without jeapordizing the wire you are using. What you want to protect against is "if" the alternator (diodes and stator) generate a serious short to ground
         
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        • prorac1

          prorac1 Well-Known Member

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          The alternator is a standard mid 70's rebuilt unit. One charge wire and two fields.

          Honestly, I've never been a big fan of fuseable links myself. Circuit breakers are usually my method of choice.

          However finding a circuit breaker that's 80 amps and not extremely large and hard to hide is proving troublesome. The largest "small" circuit breaker I'm finding is 60 amps.
           
        • prorac1

          prorac1 Well-Known Member

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          I just had a thought.

          What about an inline 80 amp maxifuse?
           
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          • 67Dart273

            67Dart273 Well-Known Member

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            If it won't pop on the alternator that would be fine. Be aware that any fuse, link, fuse, or breaker, is de-rated with engine heat.
             
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            • prorac1

              prorac1 Well-Known Member

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              That's my concern also. In the past I haven't fused the main alternator wire before.

              How have\would you do it? I'm lost on this one. It seems like every possible option has more downsides than good. LOL
               
            • prorac1

              prorac1 Well-Known Member

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              I believe with an 80 amp alternator, taking into account engine bay heat, I would want a 100 amp circuit breaker. There is no discreet way about that. LOL
               
            • 67Dart273

              67Dart273 Well-Known Member

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              You mean heat? Just locate it away as best you can. Maybe route it over to the battery and mount in front of the battery "shielded" from engine direct radiation, etc
               
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              • crackedback

                crackedback FABO Gold Member FABO Gold Member

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                Generally on cars, the battery cable runs to the starter and an Auxilliary wire runs from battery to starter relay.

                Yes, you can run a wire from the main cable starter lug to the starter relay main lug.
                 
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                • Mash340

                  Mash340 Active Member

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                  Check out Ron Francis wiring online for fuses that will work (I had ordered some things from him and plan on more as money permits) and he is not a fan at all on fusable links after reading his material neither am i
                   
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                  • 69valiant21

                    69valiant21 Well-Known Member

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                    What is the protection in stock configuration? There are no fuses or breakers from the alternator to the ammeter/"welded splice". Would the ammeter over current and pop or would the bulkhead over current and meltdown?
                     
                  • Mike69cuda

                    Mike69cuda 63 is the new 17 FABO Gold Member

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                    In general, for reliable operation, you should not operate a fuse or circuit breaker at over 80% of its rated capacity.
                     
                  • TrailBeast

                    TrailBeast Slightly Twisted Member

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                    Anyone blowing an 80 amp maxi fuse has got more problems than cable sizing.
                    I have a 60 amp alternator and using a 30 amp breaker and have never tripped it.
                     
                  • 69valiant21

                    69valiant21 Well-Known Member

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                    The alternator only supplies whats needed right? So youre not drawing more than 30 amps. But what exactly is the fuse/breaker protecting? The alternator itself?
                     
                  • TrailBeast

                    TrailBeast Slightly Twisted Member

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                    Yes kind of, but there is a burst of charge right after startup that rebuilds the battery so it can go higher.

                    If you have a short to ground in a diode inside the alternator it would burn that entire charge wire to the ground, and possibly the entire car with it.
                    If this were to happen the relay would break the connection and keep this from happening.
                     
                  • 69valiant21

                    69valiant21 Well-Known Member

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                    So why is there no protection in the original circuitry?
                     
                  • 67Dart273

                    67Dart273 Well-Known Member

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                    LOL I guess Chrysler was "cheap?" Actually "the protection" is the fuse link but this is poor at best.

                    In the early 70's my V code 70RR got tapped in the ass, and I had two Valiant loaners. One of them, a diode fell down inside the alternator when warming up, and I got to watch the entire engine harness fizzle and smoke..........and then the fuse link went. This then, was a dead short to ground on the main charging wire, and even that didn't immediately "pop" it
                     
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                    • 69valiant21

                      69valiant21 Well-Known Member

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                      Lol gives me warm fuzzy feelings knowing that.
                       
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