NOS GM 3964291 Big Block Chevy Rectangular Port Heads 396 427 454 Unused Pair
 

This is a pair of New Old Stock GM cylinder heads for a Big Block Chevy Engine. The casting number on each head is 3964291. This head is the high performance version with rectangular intake ports and closed combustion chambers. This head was used by GM on late 1969-1970 L78 396/375HP, L71 427/435HP, and 427/425HP(450HP) L72 engines which were used on Yenko and COPO cars. This head was also original equipment on the 1970 LS6 454/450HP engines. This head was also used as a direct replacement for casting numbers 3856208, 3873858, 3904391, and 3919840. What a rare find!

These heads are brand new GM castings that have never been used or installed. These were bought by a performance shop decades ago for a performance build that never happened. These are just as they came from GM with no breaks, modifications, or repairs. They look to have factory heat treated hardened exhaust seats as shown. They really don't get nicer than this.

$2250 plus shipping


Thanks,

Jason