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Alternators
Pontiac V8 Alternators
Keep the Voltage Up — Alternators for Pontiac V8s
A rebuilt Pontiac V8 usually ends up asking more of the charging system than the factory ever did. Electric fans, an EFI pump, an ignition box and a stereo all draw current, and a tired original alternator is the part that gives up first.
Butler stocks GM 10SI and 12SI case one-wire alternators from March Performance, Powermaster and CVF Racing in 100 and 140 amp, in polished, chrome and black, plus a Painless high amp wiring kit to feed the output safely.
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1. 10SI or 12SI Case
Both are GM cases and both mount conventionally. The case decides how the unit looks and what hardware comes with it.
| GM 10SI | March and CVF build on this case. The March units are 7" in diameter with 6 and 12 o'clock mounting positions at 6.6" center to center. |
| GM 12SI | The Powermaster units use the 12si style case with a smooth die cast teardrop housing, a smooth back with Powermaster vents and a gold battery post. |
| One wire | All of these are one-wire capable, which is the reason to buy one. The Powermaster units will work as either one or three wire operation. |
2. 100 Amp or 140 Amp
Both ratings are stocked across all three brands, so the decision is about load, not availability.
| 100 amp | The standard output in each family, offered by March in polished, by CVF in chrome and black, and by Powermaster in polished. |
| 140 amp | The same cases at higher output, in the same finishes, for a car carrying more electrical load. |
| Low rpm charging | CVF states its alternators are designed to work with pulleys at low rpm rather than shifting the charging range higher to claim output. March uses ultra low cut-in voltage regulators to keep amps flowing at idle, which is what a big cam and a lumpy idle actually need. |
3. Read What Is and Is Not Included
This is where alternator orders go wrong, and it differs by brand.
| Pulley and fan | The CVF and March units are supplied without a pulley or an alternator fan. The Powermaster units include a single groove V-belt pulley. |
| Charge wire | Powermaster notes the charge wire is not included, and none of these include brackets. |
| Regulator | All of them are internally regulated, so the old external regulator comes out of the circuit. |
| Origin and warranty | Powermaster states its units are made in the USA. CVF notes its units are imported and backs them with a lifetime warranty, as does March on the Ultra Series. |
4. Wiring a High Amp Alternator
A 140 amp alternator on 40 year old charge wire is a fire, not an upgrade.
| The kit | The Painless Performance high amp wiring kit covers 100 to 190 amp one-wire alternators and includes a 200 amp fuse and holder, 10 feet of 6 gauge copper wire, shrink tubing, terminals and an alternator boot. |
| Why it matters | The output cable has to be sized for the alternator's rating and it has to be fused. Neither of those is true of most factory Pontiac charging circuits. |
Work out your pulley and bracket situation before the alternator arrives. On a Pontiac that is usually the part of the job that takes the longest.
Not sure what your Pontiac needs?
Email our tech team at tech@butlerperformance.com. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.