Pontiac 326 350 389 400 428 455 MID-AIR™ MidRise Aluminum Intake Manifold [Polished] These Speedmaster main bearings are

These Speedmaster main bearings are just what you need to freshen up your engine

Speedmaster has redesigned the power gear sets to incorporate four pinion gears--unlike a stock 3-pinion style--to increase their load-handling characteristics

and then powdercoated or plated for protection and appearance

They're available in -3 AN sizes in a variety of lengths

Pontiac 326 350 389 400 428 455 MID-AIR™ MidRise Aluminum Intake Manifold [Polished] These Speedmaster main bearings areThe Speedmaster MidRise Air design features the identical plenum and runner design as the normal MidRise. The main difference is that there is an open area under the plenum chamber. This feature is sometimes called an air gap design. The air flowing under the plenum provides a cooler charge for the incoming air with less heat transfer from the engine. This cooler air charge provides additional power and torque.