NHRA Horsepower Ratings for the 273
Valve Spring information has always been a bit jaded.
The 273 2-Barrel (Camshaft Lift .400 / .411) w/.020 Lash
Valve Springs
83 lbs. @ 1.69" (Valve Closed)
177 lbs. @ 1.31" (Valve Open)
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The 273 4-Barrel' Commando (Camshaft Lift .415 / .425) w/.0.20 Lash
98 lbs. @ 1.69" (Valve Closed)
210 lbs. @ 1.295" (Valve Open)