Pontiac Tri-Power 389 Engine Upgrade - 21st Century Tri-Power - Pontiac Tech

The heads are the familiar 72cc Edelbrocks shown with 2.11/1.66 valves, Comp Cams 5/16-inch pushrods, hydraulic roller lifters, and valvesprings.

These heads were mildly ported by Ken Wilhelm at Ken's Performance in Elyria, Ohio. His approach was to concentrate primarily on the bowl area for additional flow potential.

Neither the intake (shown) nor exhaust ports were seriously hogged out, as this could hurt velocity and street performance. The procedure nonetheless produced some impressive improvements, upping the intake flow from 262 to 300 cfm at 28 inches of water, and the exhaust from 192 to 215 cfm. The exhaust to intake ratio worked out to 71.6 percent.

To augment the three-angle valve job (30, 45, and 60-degree intake; 60, 45, and radius exhaust) performed on the seats, the Edelbrock-supplied valves were treated to a custom back cut.

Crane 1.50:1-ratio roller rockers are used to further reduce valvetrain friction. Valvespring installed height is 1.700 inch.

At a glance, the Barry Grant Six Shooter setup installed on the engine looks somewhat like a factory Tri-Power, but a closer inspection reveals the new-design two-barrels and a higher rise to the intake manifold runners, as well as the trick fuel lines and linkages. More on this system will follow in Part II.

The Sabertooth GTO is the brainchild of Barry Penfound of Penfound Design. This Pro Touring machine represents a bare-bones, performance-oriented approach, paying homage to the GTO heritage while leaving off luxury equipment, such as air conditioning, power windows, and cruise control. To complement the 449ci Tri-Power engine, a Flowmaster 2.5-inch exhaust, Richmond Gear's new five-speed, and a Moser rear with 3.73 gears will be installed.

A March billet-aluminum pulley system was used for the dyno pulls.

The mixture is fired by an MSD Pro-Billet distributor with Taylor wires and NGK spark plugs. Timing is set to 36 degrees all in at 3,200 rpm.