Performance Parts - Dyno Thrashin'

We Bust Out the Wrenches & Bust a Few Knuckles in Search of Bolt-On Horsepower

John Nelson Mar 28, 2008 0 Comment(s)
0804chp_06_z Bolt_on_demon_carb 1/15

Carburetor
The bolt-on Rocker arms and new intake in place, we replaced the Chevelle's original Quadrajet mixer with a 525-cfm Road Demon vacuum secondary carb (64/78 jets). $357

The mule
The '70 Chevelle now fitted with the Lunati rocker arms and Edelbrock intake manifold. Power measured at the rear wheels.

Our take
This was a tough one--Demon recommends its carbs for modified engines, not a factory cammed, low-compression stocker like we flogged here. Although peak gains were minimal, average power was improved through the powerband. This carb also gives us a good, easily tunable foundation to work with as more extensive modifications are made to this engine.

0804chp_07_z Bolt_on_headers 2/15

Headers
The bolt-on
Doug's Headers with 15/8-inch primary tubes and 3-inch collectors. $530

The mule
The '70 Chevelle now fitted with the Lunati rocker arms, Edelbrock intake manifold, and Road Demon carb. Power measured at the rear wheels.

Our take
Our intake/carb combo got more air/fuel mixture flowing into the old Chevelle; the new headers evacuate the burnt gases much more efficiently than the factory cast-iron pieces. Another jump in power was the result.

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