Big-Block Chevy Cylinder Head ID. Finding Swap Meet Gold

When it comes to making power, big-block Chevys are known for having an easy time making a lot of it. The abundance of cubic inches is staggering, and the canted-valve cylinder heads are largely responsible since they flow a seriously large amount of air. Let’s face it, moving air makes power, and big-block Chevy heads do that very well.

The original cylinder-head design is often referred to as a 26-degree head. This is due to one of the intake-valve angles. But 26 degrees is only one of four angles needed to actually describe the big-block’s valve positioning. In reality, the exhaust valve is tilted 17 degrees relative to the deck surface, and both the intake and exhaust valves are inclined 4-degrees laterally. These various valve angles give the big-block head a characteristic “valves pointing everywhere” appearance when the valve covers are removed. This is where the “porcupine head” nickname originates.

big-block chevy head ID

The cast-iron head 3856208 was used on the 1965 Corvette with the 425 hp 396ci engine, and on Z16 Chevelles. If you find a pair now, expect to pay around $3,000.

Factory big-block Chevy heads were offered in both aluminum and cast iron, both open- and closed-chamber designs, and oval (passenger car) or rectangular (high performance) intake ports. Late-model trucks with big blocks feature an even smaller oval-intake port, frequently referred to as the “peanut” port.

When the big-block head was introduced in the mid-’60s, they all had closed combustion chambers with a roughly 100 to 109cc capacity. In 1969, the open combustion chamber was introduced and offered better air/fuel flow and combustion characteristics. The chamber size was roughly 114 to 118cc.

Big block Chevy head ID

Gen V and Gen VI big-block engines use non-adjustable rocker arms, retained by shouldered bolts. Mark IV and earlier engines use conventional threaded-studs that allow changes in valve lash. GEN V and VI heads can be converted to adjustable rockers by installing special aftermarket rocker studs, or by drilling and tapping the stud bosses for Mark IV 7/16-inch diameter rocker studs.

Most production big-block heads have similar characteristics. These include 7/16-inch rocker-arm studs (except Gen V and Gen VI) and a seven-bolt valve cover pattern. The Gen V and VI heads used a non-adjustable rocker arm with 3/8-inch studs.

While all early cast-iron and all-aluminum heads used 3/4-inch-reach gasketed spark plugs, most iron heads made after 1969 utilize smaller, taper-seat spark plugs. Aluminum heads possess two additional threaded bosses under the intake runners. This is for additional clamping and better head-gasket retention when used with blocks that have provisions in the lifter valley. The only OE blocks with these bosses were the rare ZL1 aluminum blocks, but many aftermarket blocks have this added feature. Mark IV, Gen V, and Gen VI heads all have the same head-bolt pattern, but they are not interchangeable due to different water jacket cooling passages.

Many enthusiasts have purchased a set of used heads at a swap meet, and unfortunately, ended up getting something they didn’t actually want. This is where knowledge is king. Knowing what you’re looking at can definitely save you a a lot of money – and headaches – when scouring the “used” pile. That’s why we have put together this short big-block Chevy head ID guide to help you identify that swap-meet gold.

Big-Block Chevy Cylinder Head Casting Numbers

330864: ’68 through ’84 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 396ci, 402ci, 366ci truck, 427ci truck, and 454ci truck.

330865: ’68 through ’84 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 396ci, 402ci, 366ci truck, 427ci truck, and 454ci truck.

330866: ’68 through ’78 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci truck and 427ci truck.

330867: ’68 through ’73 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 427ci truck.

336765: ’68 through ’78 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 427ci truck.

336768: ’73 through ’76 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 427ci truck.

336781: ’73 through ’85 oval port, open chambers, 2.06- and 1.72-inch valves. Used on 454ci engines.

343771: ’68 through ’86 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci truck, 427ci truck, and 454ci engines.

343772: ’68 through ’86 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci truck, 427ci truck, and 454ci engines.

343783: ‘70 through ’76 oval port, 2.06- and 1.72-inch valves. Used on 454ci truck engines.

346236: ’75 through ’87 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 454ci engine.

352625: ’70 through ’76 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 454ci Truck.

353049: ’73 through ’84 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 454ci engines.

366765: ’74 through ’78 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 427ci truck.

473328: ’68 through ’69 oval port, open chamber, 2.06- and 1.72-inch valves. 366ci truck.

3856206: ’65 and ’66 oval port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci engines. 97cc chamber.

3856208: ’65 rectangular port, closed chamber, 2.19- and 1.99-inch valves. Used on 396/425 hp, 396/375 hp Z-16 Chevelle.

3856213: ’66 through ’82 oval port, closed chamber, 2.19- and 1.88-inch valves. Used on 366ci, and 427ci trucks.

3856260: ’68 oval port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci truck.

big-block Chevy head ID

Aluminum heads with casting number 3919842 were factory cylinder heads for L89 and L88 engines. Expect to pay a lot of money if you even find a usable pair.

3872702: ’65 and ‘66 oval port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci and 427ci engines.

3873858: ’65 through ’67 rectangular port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci and 427ci engines.

3876875: ’77 through ‘85 oval port, open chamber, 2.19- and 1.88-inch valves. Used on 427ci truck.

3904390: ’67 oval port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci and 427ci engines.

3904391: ’67 rectangular port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci and 427ci engines.

3904392: ’67 rectangular port, closed chamber, 2.19- and 1.88-inch valves, aluminum. Used on 427ci L88 and L89 engines.

3904393: ’68 through ’76 oval port, open chamber, 2.19- and 1.88-inch valves. Used on 366ci truck.

3908952: ’67 oval port, open chamber, 2.19- and 1.88-inch valves. Used on 427ci truck and marine engines.

3909802: ’67 oval port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci and 427ci engines.

3917215: ’67 and ’68 oval port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci and 427ci engines.

3917219: ’68 through ’85 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci and 427ci truck engines.

3919840: ’67 through ’69 rectangular port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci and 427ci engines.

3919842: ’68 and ’69 rectangular port, closed chamber, 2.19- and 1.88-inch valves, aluminum. Used on 396ci and 427ci L88 and L89 engines.

3931063: ’68 and ’69 oval port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci, 402ci, and 427ci engines.

3933148: ’69 through ’84 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 396/265 hp, 366ci and 427ci truck engines.

3933149: ’68 through ’76 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 427ci truck.

3935401: ’68 through ’76 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 427ci truck.

3946074: ’69 rectangular port, open chamber, 2.19- and 1.88-inch valves, aluminum. Used on 427ci L88 and ZL1 engines.

3946074: ’71 rectangular port, open chamber, 2.19- and 1.88-inch valves, aluminum. Used on 454ci LS6 engines.

3964290: ’69 and ’70 oval port, closed chamber, 2.06- and 1.72-inch valves. Used on 396ci, 402ci, 427ci, and 454ci engines.

3964291: ’69 through ’72 rectangular port, closed chamber, 2.19- and 1.88-inch valves. Used on 396ci, 402ci, 427ci, and 454ci engines. Could have either large- or small-hex spark plugs. Also used on crate engines after 1970.

With the casting number 3904392, this aluminum head was used on 1967 L88 and L89 engines. The "snowflake" denotes it was cast at the Winters foundry.

3965198: ’68 and ’69 oval port, closed chamber, 2.06- and 1.72-inch valves. Used on 396ci truck engines.

3975950: ’68 through ’70 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 396ci (car), 402ci, 366ci, and 427ci (truck).

3986133: ’68 through ’85 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci, 427ci, and 454ci truck.

3986135: ’69 through ’73 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci and 427ci truck.

3986136: ’68 through ’84 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci, 427ci, and 454ci truck.

3993820: ’71 oval port, open chamber, 2.19- and 1.88-inch valves. Used on 402ci engine.

3993820: ’71 through ’84 oval port, open chamber, 2.19- and 1.88-inch valves. 454ci (car and truck)

3994026: ’71 rectangular port, open chamber, 2.19- and 1.88-inch valves. Used on 454ci LS6 engine.

3999241: ’72 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 402ci and 454ci engines.

6272292: ’70 through ’78 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 402ci and 454ci engines.

6272990: ’70 and later rectangle port, open chamber, 2.06- and 1.72-inch valves. Used on 454ci service replacement, and some Mark IV crate engines.

10052902: Oval port, open chamber, 206- and 172-inch valves. Mark IV crate engine and 427ci truck.

10101140: ’91 and later oval port, closed chamber, 2.06- and 1.72-inch valves. Used on 366ci and 427ci truck.

10114156: ’91 and later oval port, open chamber, 2.06- and 1.72-inch valves. Used on Gen V and Gen VI 454ci engines.

10141279: ’96 and later oval port, closed chamber, 2.06- and 1.72-inch valves. Also known as a Vortec 7400.

big block chevy head ID

Casting number 10141279 is for a ’96 and later engine. These are also known as Vortec heads. They also use non-adjustable rocker arms.

10487052: ’77 through ’90 oval port, open chamber, 2.06- and 1.72-inch valves.  Used on 366ci truck.

12363391: ’96 and later oval port, open chamber, 2.19- and 1.88-inch valves, aluminum, “Bow Tie” head. Fits Mark IV, Gen V, and Gen VI.

12363401: ’96 and later rectangular port, open chamber, 2.19- and 1.88-inch valves, aluminum, “Bow Tie” head. Fits Mark IV, Gen V, and Gen VI.

12558162: ’01 and later oval port, closed chamber, 2.06- and 1.72-inch valves. Gen VII “Vortec 8100” truck.

12560241: ’98 and later oval port, closed chamber, 2.06- and 1.72-inch valves. “Vortec 7400″.

12562932: ’91 through ’95 oval port, open chamber, 2.06- and 1.72-inch valves. Used on Gen V truck crate engine.

12562933: ’91 through ’95 oval port, open chamber, 2.06- and 1.72-inch valves. Used on Gen V engines.

12562934: ’00 and later rectangular port, open chamber, 2.06- and 1.72-inch valves. Used on Gen VI 502ci marine engines.

14011077: ’69 and later rectangular port, open chamber, 2.06- and 1.72-inch valves, aluminum. Used on Mark IV engines.

14044861: ’84 through ’96 rectangle port, open chamber, 2.19- and 1.88-inch valves. “Bow Tie,” aluminum, Mark IV. These are a “first design” with raised runners and a 105cc chamber.

14044861: ’96 and later rectangular port, open chamber, 2.19- and 1.88-inch valves. “Bow Tie,” aluminum. Fits Mark IV, Gen V, and Gen VI. These are a second design with raised runners and a 115cc chamber.

14081045: ’78 through ’87 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 454ci engines.

14081052: ’85 through ’87 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci, 427ci, and 454ci truck. Marked Hi Perf.

14092359: ’86 through ’90 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 366ci and 427ci truck. Marked “Hi Perf”

14092360: ’86 through ’90 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 454ci truck.

14096188: ’70 through ’71 oval port, open chamber, 2.06- and 1.72-inch valves. Used on 454ci service replacement and later Mark IV LS-6, LS-7, and 454ci HO crate engines.

14097088: ’91 and later oval port, open chamber, 2.06- and 1.72-inch valves. Used on Gen V 454ci and 502ci HO.

About the author

Randy Bolig

Randy Bolig has been working on cars and has been involved in the hobby ever since he bought his first car when he was only 14 years old. His passion for performance got him noticed by many locals, and he began helping them modify their vehicles.
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