If you're digging through a junkyard or scrolling through eBay listings, knowing how to identify camel hump heads is basically a superpower for anyone into vintage small block Chevy engines. These heads, also famously known as "double humps" or "fuelie" heads, were the gold standard for factory performance back in the 60s and early 70s. But because Chevy made millions of cylinder heads that all look somewhat similar when they're covered in forty years of grease and grime, it's easy to get confused.
You don't want to spend your hard-earned cash on a set of heavy smog heads thinking you've found a performance treasure. To make sure you're getting the real deal, you have to look at a few specific physical markers and casting numbers. Let's break down exactly what you need to look for so you can spot them from a mile away.
Look for the "Double Hump" Casting Mark
The easiest way to start the process is by looking at the ends of the cylinder heads. Chevrolet used specific raised shapes on the ends of the castings so assembly line workers could tell them apart at a glance. For camel hump heads, the mark is—you guessed it—two small humps or bumps side-by-side.
When you're looking at the front or back flat surface of the head (the part that faces the radiator or the firewall), you should see a distinct casting mark that looks like two little rectangles or "humps" with a dip in the middle. It kind of looks like a very blocky "M" or a camel's back.
It's important to note that not all high-performance heads have this mark, but it is the signature look for this specific family. If you see a single triangle, a rectangular bar, or a set of staggered lines, you're looking at a different type of head. While some of those are decent, they aren't the classic camel humps that hot rodders hunt for.
Verify the Casting Numbers
While the visual bumps are a great first step, they aren't foolproof. Some people have been known to "clone" these marks with a bit of grinding and epoxy—though that's pretty rare—and some later heads had similar marks but different internal specs. To be 100% sure about how to identify camel hump heads, you have to pull the valve covers and look at the casting numbers.
The casting number is a 7 or 8-digit code located on the top of the head, usually in the area between the rocker arms. You might need a wire brush and some brake cleaner to see them if the heads are still oily. Here are the most common "good" numbers you want to find:
- 3782461: These are the legendary 461 heads. They were used on the 327 Fuelie engines and are highly prized. They usually don't have accessory holes on the ends.
- 3890462: Often just called "462" heads, these were common on 327 and 350 engines in the late 60s. They are very similar to the 461s.
- 3917291: These showed up around 1967 and 1968. Some had 1.94-inch intake valves, others had the bigger 2.02s.
- 3927186: These are common on 1969-1970 350 engines, including the famous Z28 Camaros and LT1 Vettes. These usually do have accessory bolt holes.
If you see these numbers, you've found the real thing. If the number ends in something else, you might be looking at a "power pack" head or a later smog-era head which won't give you the same performance boost.
The Accessory Hole Situation
One of the biggest hurdles when you're trying to figure out how to identify camel hump heads for a specific project is the presence (or absence) of accessory bolt holes. On the ends of the heads, where your alternator, power steering pump, or air conditioning brackets bolt on, older heads are completely smooth.
Most camel hump heads produced before 1969 didn't have these holes. This is a huge deal if you're trying to put these heads on a "modern" engine (like something from the 70s or 80s) because you won't have anywhere to bolt your brackets. You'd have to get creative with custom brackets or drill and tap the heads yourself, which is a massive pain.
If you find a set of double humps with three bolt holes on each end, you've likely found the '186 or '291 castings from the 1969-1970 era. These are often considered the "holy grail" for street builds because you get the classic camel hump performance with the convenience of modern accessory mounting.
Check the Valve Sizes
Not all camel hump heads were created equal. Even within the same casting number, Chevrolet sometimes offered different valve sizes. The two main sizes you'll encounter are the 1.94-inch intake/1.50-inch exhaust and the beefier 2.02-inch intake/1.60-inch exhaust.
The 2.02 heads are the ones everyone wants because they flow better at high RPMs. However, there's a catch. Because the 2.02 valves are so large, the factory had to "unshroud" them by machining a little extra clearance in the combustion chamber.
If you're looking at a set of heads that have been off the engine, take a look at the combustion chambers. If the valves look like they're almost touching each other and there's a little notch cut into the side of the chamber wall to help the air get around the valve, you're likely looking at a factory 2.02 head. If the chamber wall is smooth all the way around and the valves have more "breathing room" between them, they're probably 1.94s.
Why People Still Hunt for These Heads
You might be wondering why anyone spends so much time learning how to identify camel hump heads when modern aluminum heads are everywhere. It really comes down to two things: nostalgia and "period-correct" building.
If you're restoring a 1965 Malibu or a '67 Camaro, you want the engine bay to look right. Anodized aluminum heads stick out like a sore thumb. A set of camel humps, painted Chevy Orange, looks exactly like what would have been there back in the day.
Beyond looks, these heads actually perform surprisingly well for being 60-year-old technology. They have a small, efficient 64cc combustion chamber that bumps up compression on flat-top pistons, which is an easy way to wake up a lazy engine. They don't flow as well as a modern Vortec head, but for a street cruiser that makes great "thumpy" sounds, they're hard to beat.
Potential Red Flags to Watch For
Since you're likely buying these used (and very old), identification isn't the only thing to worry about. You also have to play detective regarding their condition. Camel hump heads are notorious for cracking, especially between the valve seats.
If you're inspecting a set, look really closely at the area between the intake and exhaust valves. If you see even a hairline crack there, walk away. It's also common for these heads to have "sunken" valve seats because they were designed for leaded gasoline. Since we use unleaded now, the soft cast iron seats can wear down over time. If the valves look like they're buried deep into the head, you're looking at an expensive machine shop bill to have hardened seats installed.
Also, check for "pinned" rocker studs. High-performance versions often had the studs pressed in and then pinned with a small roll pin to keep them from pulling out under the stress of a high-lift camshaft. If you see those pins, it's a good sign the heads were intended for a high-output engine.
Wrapping It Up
Learning how to identify camel hump heads is mostly about training your eyes to see the details. Start with the "double hump" shape on the ends, confirm it with the casting numbers under the valve covers, and then check for those accessory holes to see if they'll actually fit your car's setup.
They might be old tech, but there's something undeniably cool about running a set of "fuelies" on a small block. It's a nod to the history of hot rodding. Just keep your wire brush handy, watch out for cracks, and don't let a seller talk you into a set of 70s smog heads just because they "look similar." Now that you know what to look for, you're ready to hit the swap meets and find your own set of iron treasures.