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Distributor Gears
Pontiac V8 Distributor Gears
Two Things Have to Match — Distributor Gears for Pontiac V8s
The distributor gear is the cheapest part in a Pontiac V8 that can take out the whole engine. It runs directly against the camshaft and it also drives the oil pump, so when it wears the debris goes straight into the oiling system.
Butler stocks BOP composite gears in both Pontiac shaft sizes including the Ram Air V and 455 Super Duty gear, MSD bronze and iron gears, a Comp bronze gear and a stock steel replacement, so you can match both the shaft and the camshaft.
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More About Distributor Gears
1. Start With Shaft Diameter
Get this wrong and the gear will not go on the distributor. It is decided entirely by which distributor you bought.
| .491" is the stock size | Used by factory GM HEI, Pertronix HEI, points and Mallory distributors, and by the Top Street Performance Ready to Run and Pro Billet and the RPC HEI units. A Mallory must be drilled for the larger diameter pin. |
| .500" is the aftermarket size | Used by MSD, Pertronix non-HEI billet, Holley and FAST distributors. |
| Stock steel | The replacement .491" steel gear for a stock Pontiac distributor includes the 3/16" roll pin, which you will need. |
2. Then Match the Camshaft
Shaft size narrows it to a family. Camshaft material picks the gear inside that family.
| Composite | The BOP Carbon Ultra-Poly gear is offered in both .491" and .500" and is made to replace worn bronze gears. Because it is not metal, it does not shed shavings into the oil, which is the whole argument for it. |
| Bronze | The traditional answer behind a roller camshaft. MSD's .500" bronze gear for the 8563 is machined from AMPCO 45 aluminum bronze with five percent nickel for teeth that resist wear even against a high volume oil pump. Comp's bronze gear is a .491" for HEI, points, TSP, Mallory and Unilite. |
| Iron | MSD's .500" ductile iron gear for the 8563 is Melonite QPQ coated to cut friction and initial wear, with a hardened outer layer. |
3. Ram Air V and 455 Super Duty Are Their Own Case
This is the exception that trips people up, and no amount of shaft measuring will reveal it.
| Smaller cam gear | OEM type 455 Super Duty and Ram Air V camshafts use a smaller cam gear, so they require a large diameter .491" distributor gear of their own. |
| Composite version | BOP makes that large diameter gear in composite specifically for use with hydraulic roller or solid roller camshafts in those engines. |
| While you are in there | Super Duty and Ram Air V blocks also have a larger distributor hole and need Butler's distributor sleeve for any distributor to fit. |
If you cannot say for certain what your camshaft is made of, find out before you order a gear. That one answer decides this entire page.
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.