OEM GM 3964291 Big Block Chevy Rectangular Port Heads 396 454 Closed Chamber WOW

Description

This is a pair of original GM cylinder heads for a Big Block Chevy Engine. The casting number  on each head is 3964291. These heads are the high performance version with rectangular intake ports and closed combustion chambers. These heads were 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. These heads were also original equipment on the 1970 LS6 454/450HP engines. They were also used as a direct replacement for casting numbers 3856208, 3873858, 3904391, and 3919840. What a rare find!
These heads were recently purchased out of an estate. They were last used on a 1968 Camaro drag car that had a 66 Corvette 427 shortblock installed. The car was disassembled and stored away decades ago and never touched again.  Since the heads were not original to the shortblock, I decided to list them separately. The heads appear to have been freshened up in anticipation of the next race season and never used again. I pulled a few valves and the guides appear to be new or at least have seen little use. Since these heads have sat for so long, it would be a good idea to have them gone through.
These heads look to be in good condition overall as shown. They are complete with valves, springs, retainers, guide plates, and rocker studs as shown. The intake ports are stock with light deburring as shown. The exhaust ports have been rounded at the ends of the ports to mate up with headers and will still seal to cast manifolds with no issues. There is one chamber that has been repaired as shown with a new exhaust seat added. This repair has been used since and proved as a good repair. I don't see any other breaks, modifications, or repairs to these heads. The externals are stock with the original high performance casting "humps" intact on the ends of the heads. All threads are in good condition with no thread inserts or helicoils. These are very nice factory high performance castings.
This is your chance to own an awesome HI PERF Big Block Chevy heads for your special engine or collection at a great price. Don't Miss Out!
Check out my other listings for more rare and hard to find parts.
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