Relays should be placed close...
Relays should be placed close and in a direct line to the power source load to prevent any voltage drop. A side benefit is that motors and solenoids will last longer and be more efficient when ample voltage is supplied to them. This relay is mounted on the radiator core support for the electric fan.
To finalize our solution Renka recommended we go to new heavy-duty battery cables, which we rounded up from Painless Wiring, and a battery to body ground wire. Proper ground is imperative for an electrical system to function properly. A commonly forgotten ground is the one that runs from the negative battery terminal to the body. Typically you can achieve this ground by going directly from the negative lug to the upper radiator core support. Take a look on many a new car and the odds are you will see a small wire coming off the negative terminal that’s already attached to the heavy-duty battery cable. The other end is attached to the body ground. The battery needs to be ground strap to the body, then to the engine, and then the engine to the chassis. Another typical ground will go from the valve cover to a spot on the firewall.
Voltmeters are today’s way of seeing what the vehicle’s electrical demands are doing and how these demands are being met. They can tell us many things, from how the charging system is functioning to if the loads on the wiring are too great. Knowing how to read the voltmeter is the key.
This is something that you can do at home with a few specialty tools or take to a trusted mechanic and he can give you an overview. For instance, the Auto Meter DM-40 or DM-46 Digital Volt/Ohm/Ammeter is an excellent toolbox addition for the hot rodder who likes to get into electrical systems.
The negative battery cable...
The negative battery cable often (especially Detroit iron) has a secondary wire that’s there to allow a splice for an additional battery ground to the sheetmetal; such as the radiator core support.
Battery cables are an important part of any car, hot rod, or otherwise. Except with our hot rods, when it comes to cable lengths oftentimes we need custom length cables in order to have both a good looking and well functioning pair of cables.
Painless Performance has battery cable kits to solve these problems. The PN40100 kit has a 15-foot red positive cable and 3 feet of black negative cable for those applications where the battery is under the hood, close to the engine. The PN40105 kit is for those applications where the battery is located in the trunk or away from the engine and includes a 16-foot red and 16-foot black cable. All cables are No. 1 gauge.
All Painless battery cable kits include 3/8-inch ring crimp-style copper terminals, color-coded heat shrink with glue and side-post battery adapters. The heat shrink with glue prevents moisture from entering into the cable and causing corrosion.
With a few minutes and a hammer-driven crimper, you can have professional-built cables that will carry the current needed to start your small or large engine.
The PerTronix Power Relay...
The PerTronix Power Relay Kit (PN 2001) works with most AMC, Chrysler, Ford, and pre-’74 GM vehicles and are equipped with OE resistor ignition feed wires. PerTronix Ignitor II and III ignition systems require a full 12V power connection between the ignition switch and the positive coil terminal, which requires bypassing the ballast resistor or resistor wire, and in many cases, the original resistor wire is buried in the vehicle’s wiring harness.
Relays are today’s answer to the power transfer of current to those hungry creature comforts. Relays are a lot like voltmeters. Proper use will provide relief of worry about what’s happening in your electrical system.
Proper installation of relays is just as important. Relays require protection from overloads, as any circuit does, which is commonly done with automatic reset circuit breakers or maxi-fuses. Relays need to be placed in as close to a direct line from the power source to the load as possible to prevent any voltage drop. A side benefit is that motors and solenoids will last longer and be more efficient when ample voltage is supplied to them.
Since a relay only requires about as much current as a dash light to activate, the load on the switch and its wiring is almost eliminated. The contacts inside the relay are designed to carry high amounts of current and are connected by heavy wires between the power source and the load.
We have all heard the stories about burning up electrical systems, cars overheating in traffic, and air conditioning systems failing due to the fact that the electric fan didn’t come on or didn’t have enough current so it could run at maximum speed. All kinds of problems can occur when the fan can’t produce the airflow desired in today’s cars and trucks; the myth of “a bigger alternator will fix it.” Nothing makes a fan produce airflow like old-fashioned current.