Intake Manifold
The bolt-on
We followed up the rocker swap with an Edelbrock Performer dual-plane aluminum intake. $120
The mule
The '70 Chevelle now fitted with the Lunati rocker arms. Power measured at the rear wheels.
Our take
The Performer intake flows more air than the portly factory iron piece. Equally important is that its more modern design evens out the airflow between cylinders. Both factors lead to a nice increase in power.
Before
Max torque: 265 lb-ft @ 3,400 rpm
Max power: 194 hp @ 4,200 rpm
Average torque: 247 lb-ft
Average power: 173 hp
| After
Max torque: 278 lb-ft @ 3,800 rpm
Max power: 211 hp @ 4,100 rpm
Average torque: 267 lb-ft
Average power: 189 hp
| Difference
+ 13 lb-ft
+ 17 hp
|
Roller Rocker Arms
The bolt-on
Lunati Voodoo 1.6:1 roller rocker arms. $338
The mule
A bone-stock '70 Chevelle SS convertible powered by an RPO L65, 9.0:1-compression 350 small-block, which came factory rated at 250 gross horsepower and 345 lb-ft of torque, running through a Turbo 350 trans. The only modification was a 21/2-inch dual exhaust system with turbo mufflers. Power measured at the rear wheels.
Our take
Some of the increase undoubtedly came from the extra lift provided by the rocker arms, but Lunati's James Humphrey told us most of the gain likely came from the decrease in valvetrain friction achieved by installing full roller rockers in place of the factory stamped-steel pieces.
Before
Max torque: 258 lb-ft @ 3,400 rpm
Max power: 187 hp @ 4,200 rpm
Average torque: 242 lb-ft
Average power: 171 hp
| After
Max torque: 265 lb-ft @ 3,400 rpm
Max power: 194 hp @ 4,200 rpm
Average torque: 247 lb-ft
Average power: 173 hp
| Difference
+ 7 lb-ft
+ 7 hp
|