rrs1 posted:If there is no difference in HP ratings, what happened from the early models to the 74 smog era models. The HP stayed the same? I always read this is when the "de-tuning" began.
...GROSS Horsepower is taken at the Flywheel, usually on a Dyno. 'Brake' HP. NET Horsepower is Calculated After the Drivetrain. To measure the loss of Horsepower through the drivetrain, and How Much is actually being delivered to the Ground. What Changed? What Happened to the Horsepower? 1. Open chamber heads, Smaller Valves, Dished Pistons; Lowering C.R. and with Smaller Ports. 2. Retarded Cam, Retarded Ignition Timing-Initial and Advance, Retarded. Poor quality Fuel with a Lower Octane Rating. 3. Leaned-Out Carburetor, to Pass Smog Inspection. Mal-Adjusted Carburetor.