I've been looking at the anderson b31 cam for a while now because it's easily one of the most talked-about upgrades for the old-school 5.0 Mustang crowd. If you've spent any time on the forums or hanging out at local drag strips, you know that picking a camshaft for a small block Ford can feel like a high-stakes game of Tetris. You want the power, you definitely want the sound, but you don't want to spend your entire weekend fly-cutting pistons just to make the damn thing fit. That's usually where the B31 enters the conversation.
The beauty of the Anderson Ford Motorsport "B" series cams, and the B31 specifically, is that they were designed with a very specific goal in mind: making the most possible power without turning the engine into a ticking time bomb. It's a hydraulic roller cam that occupies this perfect middle ground. It isn't so aggressive that you lose all your low-end torque, but it's definitely not a "stock plus" grind either. It's got some teeth to it, and that's why it's stayed relevant for decades even as newer engine platforms have taken over the spotlight.
Why the B31 Stands Out
When you look at the specs, the anderson b31 cam usually sits around .544 lift on both the intake and exhaust sides when you're using 1.6 roller rockers. The duration at .050 is typically 218 degrees on the intake and 228 on the exhaust. Now, those numbers might sound like Greek to some people, but here's what they mean in the real world: the cam is designed to breathe. It moves the power band up just enough to make those gear shifts feel meaningful, usually pulling hard from about 2,500 RPM all the way up to 6,000 RPM.
One of the main reasons guys go for this cam over, say, a generic letter cam from the big manufacturers, is the ramp rate. Anderson designed these to be aggressive. They snap the valves open quickly and hold them there, which is how you get that extra "oomph" without needing a massive amount of total duration. It's a clever way to get more air into the cylinders without making the car impossible to drive at a red light.
The Piston-to-Valve Clearance Factor
Let's talk about the elephant in the room for any 302 owner: piston-to-valve clearance. If you're running a stock bottom end on an '87 to '95 Mustang, you know those factory pistons don't have very deep valve reliefs. This is where the anderson b31 cam really shines. It was specifically engineered to clear stock pistons.
I can't tell you how many people I've seen buy a massive cam only to realize halfway through the install that they have to pull the heads back off and start cutting into their pistons. It's a nightmare. The B31 avoids that drama. Now, I'll always tell people to "clay" the engine and check clearance anyway—because every engine is a little different and head gaskets vary in thickness—but nine times out of ten, this cam drops right in and clears. That peace of mind is worth its weight in gold when you're working in your garage on a Sunday afternoon.
How It Sounds and Drives
We have to be honest with ourselves—part of the reason we swap cams is for the sound. Nobody wants a modified Mustang that sounds like a silent vacuum cleaner. The anderson b31 cam delivers a very distinct, choppy idle. It's got that classic "lope" that tells everyone at the gas station that there's something more than a stock motor under the hood. It isn't so radical that the car stalls out every time you push the clutch in, but it's definitely noticeable.
On the street, the drivability is surprisingly good. Some cams make the car "buck" or surge at low speeds, especially if you're trying to cruise through a parking lot in second gear. The B31 is pretty well-behaved. As long as your tune is decent and your idle speed is set correctly, it's a very livable setup. You can take it on a road trip, sit in some traffic, and not feel like you're wrestling a race car the whole time. But once the light turns green and you bury your foot, it wakes up in a hurry.
Supporting Modifications
You can't just throw an anderson b31 cam into a completely stock engine and expect it to work miracles. To really see what this thing can do, you need to think about the rest of the puzzle. First and foremost: valve springs. Please, for the love of your engine, do not use stock 302 valve springs with this cam. The .544 lift will likely cause coil bind on factory springs, or at the very least, they won't have enough tension to keep the valves from "floating" at high RPM. A good set of upgraded springs is mandatory.
The intake manifold and cylinder heads are the next big pieces. If you're still running the factory E7 heads and a stock intake, the B31 will feel a bit choked. It'll still work, but it's like trying to run a marathon while breathing through a straw. If you pair this cam with a set of GT40, Trick Flow, or AFR heads and a decent long-runner intake like a Holley Systemax or an Edelbrock Performer, the car will feel like a completely different animal. It's all about the combination.
Naturally Aspirated vs. Forced Induction
Another cool thing about the anderson b31 cam is its versatility. While it's a fantastic naturally aspirated cam, it's also very popular with the centrifugal supercharger guys. If you've got a Vortech or a ProCharger hanging off the side of your engine, the B31 handles the boost exceptionally well. The exhaust duration helps get those spent gases out of the way so the blower can cram more fresh air in.
I've seen plenty of setups where a basic 302 with a B31 cam and a small blower makes well over 400 horsepower to the tires. That's more than enough to get a lightweight Fox Body into the 11-second range at the track, which is plenty of fun for most people. It really is a "jack of all trades" kind of camshaft.
Installation Tips
If you're planning on doing the install yourself, just take your time. Swapping a cam in a Ford small block isn't overly complicated, but there are a few places where things can go sideways. Make sure you have a good quality timing chain set—preferably a double roller. You're already in there, so you might as well replace the old, stretched factory chain.
Also, don't forget the assembly lube. Lather that anderson b31 cam up before you slide it into the block. Even though it's a roller cam and doesn't require the same "break-in" period as an old flat-tappet cam, you still want that initial protection until the oil pressure builds up. And while you're at it, check your pushrod length. Swapping a cam can sometimes change the geometry just enough that you might need slightly longer or shorter pushrods to keep the rocker arm tip centered on the valve stem.
Final Thoughts
At the end of the day, the anderson b31 cam remains a top-tier choice because it works. It doesn't try to be something it's not. It's a street-friendly, high-performance camshaft that rewards you with a great power band and a killer exhaust note. It's survived the test of time because it hits that "sweet spot" that most enthusiasts are looking for.
Whether you're building a weekend cruiser or a dedicated street/strip car, this cam is a solid investment. It's one of those parts that you install and immediately feel the difference. You aren't just gaining a few horsepower here and there; you're changing the entire personality of the car. If you want that classic 5.0 pushrod scream and a car that actually moves when you tell it to, the B31 is definitely worth a look. It's an old-school solution that still kicks plenty of tail today.