Heads

Small Block Mopar 273 Cylinder Head
Casting #2658920


Came from the factory with the Combustion Chamber at a range of 61 to 64 CC's.

On the 1966 and 1967 Commando 273, if the Piston Top (flat section) is set at
{-.011} below the block deck, the Cylinder Head will require 57.3 CC's to achieve a
10.5 - 1 Compression Ratio with .020" thickness Head Gaskets.

On a 273/180 HP 2-Barrel engine, if the Flat-top piston is set at {-.011} below the
block deck, the Cylinder Head will require 57.3 CC's to achieve an 8.8 - 1 Compression
Ratio with .020" thickness Head Gaskets.

For every .0065" milled off the Cylinder Head, 1 CC from the Chamber Volume will be
deducted.

Bringing the CC Volume in the Cylinder Head 'combustion chamber' down to 51.3 CC,
should increase the Compression ratio by .75

The Intake Port measures at 127 CC in Volume
The Exhaust Port measures at 60 CC in Volume.

The 'general rule' is that without larger Valves and Port work, these
Cylinder Heads will top out at 300 to 315 Horsepower.