Pontiac 326 350 389 400 428 455 MID-AIR™ MidRise Aluminum Intake Manifold [Polished] Speedmaster one piece silicone rear

Speedmaster one piece silicone rear main seal

They are manufactured from machined steel and offer excellent valve spring location

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

Provide safety in the event of too much pressure due to overfilling or heat

Pontiac 326 350 389 400 428 455 MID-AIR™ MidRise Aluminum Intake Manifold [Polished] Speedmaster one piece silicone rearThe 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.