- Home »
- Catalog »
- Engine Components- Internal »
- Bearings »
- Main Bearings
Main Bearings
Pontiac V8 Main Bearings
Start With the Journal — Main Bearings for Pontiac V8s
Main bearings carry the crankshaft, and on a Pontiac V8 there is no universal set. The block dictates the journal size, the crank's finished grind dictates the undersize, and how hard the engine gets run dictates the material and groove pattern.
Butler splits this section three ways — 301, 326-350-389-400 and 421-428-455 — and stocks Clevite, Federal Mogul and King Racing sets across standard and undersizes, including extra-clearance and reduced-clearance options.
Select a Sub-Category
Popular Brands:
More About Main Bearings
1. Three groups, one deciding number
Everything under this category is organised by main journal diameter. Pick the page that matches your block and the rest gets easy.
| 326, 350, 389, 400 | The 3.00" main family. Deepest selection Butler carries, across all three bearing brands. |
| 421, 428, 455 | The 3.25" main family. Clevite and Federal Mogul sets, including a race option with grooving top and bottom. |
| 301 | Its own small family, separate from everything above it. Pontiac's late small-displacement V8 does not share a main bearing with the 326-455 range. |
2. Undersize follows the crank, not the engine
If you remember one thing from this page, make it this one.
| Order to the grind | Sets are stocked standard, .010", .020" and .030" depending on the line. A crank that has been turned .010/.010 takes .010 bearings, whatever the engine is. |
| Unknown crank, measure it | A used crank of uncertain history gets miked before anything is ordered. A machine shop will give you the finished sizes in writing. |
| Clearance is separate | Several lines are offered with a thousandth more or less oil clearance built in. That is a build decision layered on top of the undersize, not a substitute for it. |
3. Groove and material, briefly
The detail lives on each family's page, but the shape of the choice is the same on all three.
| Groove pattern | Half groove keeps more load-carrying surface. Three-quarter and full groove send more oil up to the rod bearings, which matters as rpm climbs. |
| Tri-metal | The conventional street and street/strip answer, and what Butler uses in most of its own builds. |
| Harder-face options | King's HP series exists for applications wanting something harder than a babbitt top layer, including engines running nodular cast iron cranks. |
Have the block, the measured journal size and the planned rpm ready. Those three answers land you on the right page and the right part number without a second call.
421-428-455 Main Bearings 326-350-389-400 Main Bearings
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.