This is a pair of original GM 3946074 aluminum cylinder heads for Big Block Chevy engines. These heads have rectangular intake ports, round exhaust ports, and open combustion chambers.
The 3946074 heads were used on the following applications: 1969 ZL-1 427/430HP All Aluminum engine, 1969 2nd design L-88 427/430HP engine, and the 1971 Corvette LS6 454/425HP engine. These heads were also sold over the GM parts counter for years. It is not uncommon to see a set of these 3946074 heads for sale. However, it is uncommon to see a real deal 1969 dated set. These heads are just that. The casting dates for 1/14/69 and 3/26/69 as shown. This is a matched set that I believe have been a pair since new.
These heads are in good condition overall. They removed from a running 427 engine in a 1968 Corvette. The heads were disassembled, cleaned, and checked for cracks, repairs, and damage. There are no breaks, cracks, welds, or other significant damage. The casting numbers, date codes, and Winter\'s Snowflake casting marks on the tops of the outer exhaust ports are intact. All of the rocker studs are intact and in good condition with no breaks or repairs. The intake ports have been deburred and are not heavily ported. The exhaust ports are stock with no port work. The combustion chambers are in good condition with some nicks from debris getting into the cylinders. All 4 deck surface indicators can on the outer corners of the deck surfaces can be seen showing the heads have not been excessively milled. The deck surface has been upgraded for use with o-ring style headgaskets as shown. I believe these can still be used with standard headgaskets, please check with your machinist. There are helicoils/thread inserts in many of the threads which is common and a nice upgrade. Most aftermarket aluminum heads come with helicoils already installed in all threads. A handful of the helicoils will need to be redone. These heads could likely be installed as is. I recommend having a machine trust go through them, add valve springs for your cam, etc. before using them for piece of. These real deal 1969 dated heads are very hard to find. Don\'t Miss this very reasonably priced set or you will be kicking yourself later.
This is your chance to own the real 1969 dated 3946074 heads you have been dreaming about 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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