na svt
07-03-2007, 11:54 PM
These heads were on the motor that powered Shawn Johnson's NMRA Factory Stock car to two consecutive Championships; 2005 and 2006. All the work was done by Modular Performance and the heads are 03/04 castings.
The valve and springs are FR500 parts and the retainers are titanium. Up to 1996, the 4v motors were allowed to have the same combustion chamber volume as the 2v engines, which is 44cc. With the smaller chamber size these heads with flat top pistons result in an 11.8 to 1 compression ratio (give or take a little). On a stock longblock these heads will make the compression ratio about 1 point higher than stock, so roughly 10.8 to 1.
The heads were selected from a large number of 03/04 castings and selected for their high flow numbers.
They are in superb condition, ready to bolt on and would be for a high compression street motor or on a stock shortblock cobra or Mach 1.
The valve and springs are FR500 parts and the retainers are titanium. Up to 1996, the 4v motors were allowed to have the same combustion chamber volume as the 2v engines, which is 44cc. With the smaller chamber size these heads with flat top pistons result in an 11.8 to 1 compression ratio (give or take a little). On a stock longblock these heads will make the compression ratio about 1 point higher than stock, so roughly 10.8 to 1.
The heads were selected from a large number of 03/04 castings and selected for their high flow numbers.
They are in superb condition, ready to bolt on and would be for a high compression street motor or on a stock shortblock cobra or Mach 1.