66 273 engine roller rocker

Welcome to FABO Sabre. What you have is probably a 185 hp. 2 barrell motor with iron adjustable rocker arms. The stock cams were solid lifter cams and needed adjustable rockers for the proper valve clearance. The compression is around 8.5:1 and the compression is made by the pistons and not the cylinder heads. These are good running engines and respond to 4 barrell intake/carbs and slightly larger cams. In a early Dart/ Valiant, or Barracuda they will get you 15-20 mpg on the highway depending on which trans and rear gear. toolmanmike