increase HP on a 273

(Trying this yet again! UGH!)

OK, below is a list f parts that I would consider for upgrading the engine.

Intake; I would look at the Edelbrook Performer or Weiand Action Plus. The small port intakes would be very good for the small engine.

Carb; A 500 cfm Edelbrook/Carter would be right in there though not more than a 600 cfm carb for the 273.

Cam; A cam must work with the rest of the combo. The rest of it is rear gear, tire size and stall of the tranny. I'll assume it is set up from the factory as a people mover equiped with 2.76 or the like gears and the engine is a low compresion engine rather than one of the hi comp HP engines.

For this, I would look at a split duration cam with 6*'s more on the exhaust at a min. since your useing exhaust manifolds. Also, look at the cams RPM range of operation. Since the car was more likely set up as a people mover with low numeric gears, a cam of not more than 216*'s @ .050 should be about the max to look at.

If you have 3.21 gears, 218 @ .050 would be fine.
3.55's and you could move to a 220 @ .050 cam at max.
I say at max because if you exceed this spec, your likely to have a dead spot down low and require yourself a higher stall converter. (More money!)

Comp Cams has a XE256 that would work well.