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326-350-389-400 Main Bearings
Pontiac V8 326-350-389-400 Main Bearings
The 3.00" Main Family — 326-350-389-400 Main Bearings for Pontiac V8s
The 326, 350, 389 and 400 share a 3.00" main journal, which is why they share a main bearing set. This is the most heavily stocked main bearing group Butler carries, and it runs from a plain tri-metal rebuild set all the way to a drag race bearing.
All three lines are here: Clevite in half groove tri-metal and full groove P series, Federal Mogul in standard tri-metal and Competition Series Super Duty alloy, and King Racing HP series, in standard through .030" plus extra-clearance and reduced-clearance variants.
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More About 326-350-389-400 Main Bearings
1. One bearing, four engines
The small-main Pontiacs all take the same set, which makes this page simpler than it looks at first.
| What fits | Clevite and Federal Mogul catalogue these as 350, 389 and 400 sets, and Federal Mogul's tri-metal line adds the 326 explicitly. King catalogues its set as Pontiac 326-400. |
| What does not | The 421, 428 and 455 use a 3.25" main and have their own page. There is no crossover. |
| Sold as sets | Complete main bearing sets including the thrust bearing, not individual shells. |
2. Groove pattern — half, three-quarter or full
This is the choice that distinguishes most of the part numbers on this page, and it is about how much oil gets sent up to the rod bearings.
| Half groove upper | Clevite's tri-metal G series set uses a 1/2 groove upper bearing, and Federal Mogul's tri-metal set is also 1/2 groove upper. This is the conventional street arrangement — more bearing surface carrying load. |
| Three-quarter groove | Federal Mogul's Competition Series is a 3/4 groove design in Super Duty alloy, the H-14 spec. A middle ground between load area and oil flow. |
| Full groove upper and lower | Clevite's P series set is fully grooved top and bottom. Clevite's own guidance says the P series is most often fully grooved to maximise oil flow to the rod bearings, and points it at extremely high rpm where rod bore close-in becomes severe. |
3. Bearing material
What the bearing face is made of matters more as rpm and crank hardness go up.
| Clevite tri-metal | The G series uses a tri-metal construction — a soft lead-alloy outer layer, a copper-lead centre and a rugged steel backing. Clevite's claim is that it withstands the friction, dirt, misalignment, wear, corrosion and heat that chew away at bearing and journal life. |
| Federal Mogul Super Duty alloy | The Competition Series H-14 spec, which is the performance step in the Federal Mogul line for these engines. |
| King HP series | Developed mainly for drag race applications needing a material harder than a babbitt top layer, using King's Alecular metal structure. King also recommends it for many performance applications with nodular cast iron crankshafts — street, strip and some levels of circle track. It is the answer when a tri-metal bearing's babbitt overlay has been extruding over the sides, migrating, or getting physically removed by the crank. |
4. Undersize and clearance
Two different numbers that people mix up constantly. Size follows the crank; clearance is a build decision.
| Undersizes | Clevite's half groove set is stocked standard, .010" and .020"; the full groove P series goes standard through .030". Federal Mogul's tri-metal line covers standard through .030" and the Competition Series covers standard, .010" and .020". Order to the grind on the crank. |
| Less clearance | Federal Mogul catalogues a .001" set that takes a thousandth of clearance out. That is for a specific build target, not a way to fix a worn journal. |
| More clearance | King offers an extra-clearance set and a .001" oversize set in the HP line for builders who want to move clearance the other way. |
| Verify it | Whatever you order, check the assembled clearance. The bearing is only half the equation — the align bore is the other half. |
Bring the measured main journal size and tell us the rpm the engine will actually see. Those two answers pick the line and the size in one pass.
Not sure what your Pontiac needs?
Call our tech team at 866-762-7527. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.