The valve guides are integrally cast in the head and consume the major length of the valve stem, cutting down on excessive valve side play. All ports are large in stock form, indicating a minor bit of shaping and clean-up only. The valves are big, intakes measuring 1.92-inch and exhausts 1.66-inth. The intakes have a 30-degree seat angle, the exhausts use a 45-degree seat for better heat dissipation. Lift is set at .395 to .417-inch, which is quite reasonable for a hot street machine. The cast iron camshaft has lobes ground at an angle to cause the lifters to rotate and is supported by five bearings. Special high-performance, hydraulic valve lifters are included. The 335 engine has a valve timing of: 273 intake, 289 exhaust (duration in degrees), 54 degrees overlap. The 360 engine features an intake of 288 and exhaust of 302, with an overlap of 63 degrees. Dual exhaust with low restriction mufflers and resonators is stock. The 335 lip engine is fitted with a single 4-barrel carburetor. The bigger 360 engine has three two-throats with mechanical progressive linkage. Throttle bore area of the single quad is 7.62 square inches compared to 12.19 for the triples. Under the conditions we've just listed, the 335 produces 431 lb/ft torque at 3200 while the 360 register 424 at 3600. Under almost any set of rules, the 389 GTO engine must be rated as very good in showroom trim, and superb with a little "hot rod english." A transistor ignition is available, as is a seven-blade declutching fan. Chrome valve covers and carb cleaner sheet metal adds to appearance, if not performance. To take care of any unusual heating problems, heavy duty radiators are listed as options.
The bodies are of standard sheet steel, with no optional aluminum or fiberglass parts available f or racing purposes. As it is, the car can be ordered without underseal or other sound deadening material, which cuts about 130 pounds in total weight, and further
.A 2-speed torque converter automatic is available, with a max torque multiplication off the line of 3.87 to 1. The governor is set for automatic upshift at 5200 rpm.
The GTO is equipped with two basic ohv's, both displacing a cool 389 cubic inches. The only difference between the two is a little matter of 25 advertised horsepower, derived at through camshaft timing and carburetion. The 389 engine is a short stroke, 90degree V design, with a reasonably thinwalled alloy cast iron block. The bore is 41/,(-, inches, while the crank strokes a neat 3% inches. The flat-top aluminum pistons have a compression ratio of 10.75:1 and are flycut in the crowns for valve clearance. The block has five main bearing supports, providing a very strong bottom end for the cast pearlitic malleable iron crankshaft. The crank is fitted with heavy duty Moraine-400 aluminum-onsteel main and rod bearings. Journal diameters are 3-inch, which means that a good amount of modifications can be made to the engine without undue worry about the bottom end falling out. The heads are identical, side for side and are designed to flow water completely around the valve seats for better cooling.
ABOVE - Jerry Jardine installed a set of his popular three-port headers on the car before last part of the power tests. Shown here installing the units while visiting Don Nicholson watches, ferry promised more power. The promise was fulfilled. One dyno owner reported hp increase of 20 with such a set-up on an identical machine.
LEFT-New steel wheels offered as Rally options by Pontiac are stamped by Budd. Cooling slots help dissipate heat generated by larger diameter, metallic brakes.