Figure 25-amps for all the stock lights and accessories and then figure and add the amps for what ever devices you are adding. Then add those amps to the 25 to see if the 63-amp 10SI will do or if you want a higher output 10SI. Formula for conversion of Watts to Amps; Watts/Volts = Amps; ie, 60-watt headlight and your 12-volt battery is figured 60-watts/12-volts = 5 amps. Amperage draw of common automotive lamps: Instrument/Indicator Lamps #53(x) .12-amps (1/8th amp); Stop/Tail/Turn Signal Lamps #1034 1.8-amps; Stop/Turn .6-amps; Tail Light #1157 2.1 amps.

The internally regulated 10SI 12-volt alternator conversion does not need and cannot use any existing or external voltage regulator so remove what you got. An alternator requires a negative ground. You will install the battery with the negative post grounded. The ammeter will read backwards; e.g., discharge while charging, if you don't change the wires from one post of the ammeter to the other and vice verse. Ford loop-type ammeters can be reversed by pulling the wire out one side of the loop and threading it back through from the opposite side. The test is to see that the ammeter shows a discharge while cranking the engine with the ignition switch turned on. On a running engine you turn on the lights and the needle should move in the discharge direction.

It's a good thing to reverse the primary (low voltage) wires on the ignition coil by moving all the wires on the coil's positive (+) terminal to the coil's negative (-) terminal and vice verse. The ignition coil wire swap is not that big a deal so don't fret if you can't get it done. You can continue to use a stock 6-volt ignition coil if you install a voltage drop resistor. Fact is, before electronic ignition, all coils were 6-volt but some had the voltage drop resistor built in so they were called 12-volt coils. Most any normal automotive starter and electrical accessory can operate as either negative or positive ground with no change in performance or direction. Radios for positive ground may not operate on negative ground so verify yours will work before making the conversion. When converting to 12-volt from 6-volt the radio, light bulbs, flashers, washer motors and other voltage sensitive devices must be replaced with 12-volt equivalents. 6-volt accessories like gas gauges, ahoogah horns and even some items mentioned may not be an insurmountable challenge when converting to 12-volt so contact me if you need to deal with the situation where a 12-volt replacement is not an option.

Another consideration is that the SI automotive alternator is designed to operate at the relatively high RPM of a modern (overhead valve) automotive engine. Without excitation from the battery, the automotive alternator doesn't begin to output (self-excite) until RPM gets up to 1700-1800. Some Delco SI alternators have been modified to a 1-wire configuration (no excite voltage from the battery) that totally depends on engine RPM to get up there so the alternator will self-excite. My Ford tractor idles at less than 400-rpm and normally operates just over 1500 so I would always have to be certain to rev it up to where a self-exciting alternator would begin to output regardless of how I'm otherwise operating the tractor. Some of the 1-wire alternators have been modified to self-excite at a slower speed than 1700-rpm but the 3-wire will always output at a slower RPM because it is excited by the battery voltage via the ignition switch right from the git-go. The 3-wire with a diode in the excite wire will give you the slowest turn-on possible and eliminate any battery-draining leakage current during long down times or if there is some problem in the alternator. The 3-wire is straight forward with one wire going no farther than the alternator itself. The 10SI alternator wire harness with the Delco Alternator-plug (DA-plug) makes it a snap to wire up the 3-wire alternator. The harness also makes it simple to keep the dash light in the circuit. No additional resistor is required when using the diode.

Modern belts do not fit older vehicles. Vintage autos likely have the 1/2" wide crank and water pump pulleys and ag or industrial engines may have 5/8" or larger pulleys. To get the 12-volt conversion right means you need to measure the pulley on the crank or water pump and install the proper wide-belt pulley on the alternator. Don't measure the existing v-belt because no telling how that type and size belt came to be on your engine. There is a lot to v-belts and running the improper belt can be no end to problems and premature failure. If you can't figure the correct belt for your project then contact me and we will get a belt that goes on, stays on, and can last thousands and thousands of hours of operation.

I list brackets for most applications but if you have something else again then let me know what and why and see if I can fix you up. Compare fit and function to your project and you will see this 12-volt alternator conversion thing isn't going to be such a big deal. My products are heavy-duty, high-quality, and nearly all of it is made in the USA. I work hard to provide value and a commitment to customer service.

1954 Packard Clipper Deluxe Sedan I-8 engine

The alternator shown in the Packard photo above has the wire harness DA-plug receptacle turned to the engine so you can't see it in that picture. If that's undesirable then the alternator can be "clocked" to bring the receptacle around to another location 90- or 180-degrees off. Two things to keep in mind: one, the ring between the case parts goes with the rear case and not with the front (drive-end) case. Two, you have only a long 1/16" difference between the brushes slipping out of the brush holders and not slipping out of the brush holders and you do not want the brushes to slip out of the brush holders. With that in mind, remove the 4 long case bolts. Ease the case apart a total of 17/32" (you begin with 7/32" space so the total movement will be another 10/32") and then rotate the drive-end case. You'll know the brushes slipped out of the brush-holders when the case won't go back together with only gentle to moderate pressure. If the brushes slip out than pull the case completely apart and reset the brushes. There are holes in the brush-holder for a piece of wire that can retain the brushes and springs while you reassemble the case. The wire must be long enough to stick out the hole in the back of the case. Other than wanting more room for more fingers, it's no huge deal; 2-minutes on a good day, 20-minutes on a bad day. Just remember, easy does it and if you have to push anything with more than a gentle to moderate pressure then it's not right and you need to back up to see what you got wrong; that includes springs, brushes, wire, and case halves.

You have dash gauges or you have an instrument cluster. Older temperature and pressure gauges will not be electrical gauges. Some electrical dash gauges run right off 6-volts (mostly GM) while other dash gauges and probably all instrument clusters use 5-volts. The 5-volts is done by an electro-mechanical voltage regulator (IVR) fed hot with 6-volts. The IVR is a 1" X 2" sardine can with wires kinda thing that is going to be separate from the dash gauge but will be attached to the back of the instrument cluster. It may be built in to some instrument clusters (AMC/Jeep). An IVR can be retained but the mechanical contacts and heater are a source of problems and change. Better to remove and wire around that IVR and use a 5-volt voltage reducer to update those gauges. Use a 12-volt to 6-volt voltage reducer to update gauges not associated with a IVR or to feed an IVR hot. Use a 12V to 6-volt regulator/reducer made to replace the IVR if you would like to remove that electro-mechanical device to upgrade your instrumentation.

Voltage reducing resistors are not the way to go with dash gauges and instrument clusters. Use a resistor and the needles will move but the gauges won't be telling you what you want to know. Put a little thought and effort into the voltage, use the correct parts, and those old gauges can work very well and give you better information than they were able to provide the day your vehicle came off the production line.

I hope you found some info you can use in my guide. I'm sure the guide can be improved so I would be happy to hear from anyone with better, different, or more information. My Store items are quality and have good value so please take a look at my 12-volt conversion parts. Please send pictures of my parts on your ride! Happy motoring everyone.

DISCLAIMER: due to the many different types of vehicles it is impossible to provide instructions for each possible application. The information provided herein is offered to provide general instructions for a qualified automotive electrician. The purchaser must make the determination of the suitability of any of these products for any specific application. The information presented is my best effort but you take it 'as is' and with no warranty.