273 Boring
I bored my '65 273 .060 over which made it 282 cubic inches. Since it was putting out more than 1 horsepower per cubic inch, the extra displacement was good for about 10 horsepower. Overboring also raises compression ratio slightly. I used old school TRW domed/forged pistons that were advertised as the same compression ratio as the factory Commando pistons @ 10.5:1. Today's domed pistons for the 273 actually work out to only about 9.5:1.
I bored my '65 273 .060 over which made it 282 cubic inches. Since it was putting out more than 1 horsepower per cubic inch, the extra displacement was good for about 10 horsepower. Overboring also raises compression ratio slightly. I used old school TRW domed/forged pistons that were advertised as the same compression ratio as the factory Commando pistons @ 10.5:1. Today's domed pistons for the 273 actually work out to only about 9.5:1.
