Asking around for how to choose a camshaft for small block chevy is like asking for the best haircut that fits a guy. It’s personal and what applies to A might not apply to B.
Ask yourself, how will the engine be used? Race cams are very different from street cams.
So, will it be a heavy-duty that you frequently use every day or a BMW-5 series that rarely hits the street except on private occasions? You cannot overlook the intended use.
Your car’s weight, compression ratio and transmission mode of the gear are other vital factors that matter as well.
Budget is also important, and we can decide to go hydraulic or even mechanical if we need more power.
In this post, we will discuss critical factors that play a role in how to choose a camshaft for small block chevy.
Let’s get to it!
What is Camshaft?
A camshaft is a mechanical rod that uses a slider-crank mechanism to convert rotational motion into linear motion.
This linear motion is the operating principle behind the closing and opening of the piston engines’ valves.
We’re talking about how the rod (shaft) surrounded by cams continuously slides against another machinery (the valves).
As the rod rotates, its lobes (cams) rotate too and push against the valves on the engine pistons forcing a closing and opening effect.
Hence, we can now say a camshaft is a device that opens or closes the piston’s engine’s valve.
For modern engines, you’ll find the camshaft above the cylinder head of the engines.
The engine is either a Single overhead cam (OHC) engine or a Dual overhead cam (DOHC) engine. The DOHC has two camshafts (intake and exhaust) while the SOHC has just one camshaft.
Besides, camshafts are from metals such as cast iron or even the forged ones. So, rigidity is assured.
Timing is also vital since the valves must open/close at regular intervals as the shaft keeps rotating. Read on to understand the working principle of the camshaft in a typical engine.
How Does it work in Engine?
As we earlier discussed, camshafts are placed in the piston engines. However, these pistons on the engine are more than one.
So, just one cam can’t drive them all. This is where the camshaft comes in – a shaft having many cams.
Understanding the working principle of the camshaft in the engine involves knowing what happens when it rotates.
So, when the shaft rotates, its shape presses on the piston valves while different processes simultaneously occur in a cycle.
These are the intake, exhaust, compression, and ignition processes.
The camshaft is then responsible for controlling how the valves take in air/fuel, what valves are exhausting, and what is closed during the same time frame.
So, there is a bit of critical timing here which has to be near perfection as much as possible.
As a result, chains (to the crankshaft) or timing belts are used in connecting the camshafts to the engine to ensure correct timing during each process cycle.
The camshaft’s shape is also vital here as it also affects the valves’ opening/closing speed. Checking out for the shape is often referred to as the variable valve timing. The YouTube video below explains this more.
When a camshaft needs to change
If your car is beginning to give you funny rattling sounds before it starts, then you might consider taking it to the repair shop for a camshaft change.
Other reasons for a camshaft change are apparent wear and tear in the camshaft lobe design.
Thus, we might say that you do not need to bother about a camshaft change except there’s a noticeable fault. Isn’t it?
NO! While the existence of apparent faults demands a change of camshaft, a replacement is not ONLY based on this condition.
These days, modern engines come with camshaft lobe designs that are relatively resistant to noticeable wear and tear.
In some cases, the top of the lobe is not even visible, and as such, wear in the camshaft can be easily overlooked.
Therefore, when it comes to deciding on changing your camshaft or not, we will advise you to consider your budget.
Count the cost of a replacement compared to using what you have.
If you have the money, it is best to take the camshaft to a machine shop with the necessary tools suitable for modern camshafts.
However, it would be best if you never hesitated to get a replacement if you noticed apparent wear.
How to Choose Camshaft For Small Block Chevy?
Having an engine with an unsuitable camshaft is almost like having none at all. The camshaft is vital because it is the valves’ propeller responsible for the engine’s perfect working conditions.
As a result, how to choose a camshaft for small block chevy is more than just talking to an engine builder.
You also need to know cams that will help you give the builder a perfect description for him to work. To start with, we have recommended the following steps for you:
1. Be honest and realistic about what you want
As simple as this sounds, it is a commonly ignored rule that often causes dissatisfaction between people and their engine builders.
You need to be honest about the intended engine use to avoid over-camming the small block chevy.
2. Consider the compatibility of your car with the engine
Another essential point to consider is the average running requirement of your vehicle to your preferred engine choice. What’s your car weight? Does it have an air-conditioning system?
3. Don’t make the error of building the engine around the camshaft.
Instead, you should always consider the engine first before the camshaft. The engine airflow capabilities will determine the camshaft that will open and close the valves at the right time.
Essential points list before selecting camshaft especially for small block Chevy
Now that we know the necessary factors to consider, there is also the need to identify the guide points for how to choose a camshaft for small block chevy.
Please read below for our essential point lists that we think can make your selection process more comfortable.
While we’ll advise you to always go for top quality and the best alone, it is also essential to consider your budget.
Small block chevy is quite popular, so there is a high chance of getting a budget-friendly one with the right RPM operating conditions for both high and low speeds.
2. RPM Range
Like we said earlier, always build your cam around your engine. Your engine’s operating range will determine the camshaft’s RPM range that will give the most power.
While a valve lift is essential, it must not be too high or too low for the engine. Optimum valve lift will allow the right proportion of air and fuel mix to ensure perfect combustion.
4. Compression Losses
The cams that will be best for your small-block chevy should be one that closes fast and tight too. A lose one will lose air and overly expose the exhaust valves.
5. Lobe Separation Angle
It refers to the angular relation between the intake cam and the exhaust cam along their centerline. The angle formed determines the timing of valve opening of intake and exhaust cam lobes.
6. Performance & Compatibility
After deciding the torque value you are seeking, you also need to check the operating condition for your cam choices for the one that best matches your specification.
How To Tell If Your Camshaft has Issues
In case you do not already know, camshafts have what is called the position sensor. See the operating principle below.
This sensor obtains real-time information about the camshaft condition and sends it as a signal to the Engine Control Module (ECM) of your automobile.
However, this camshaft sensor works hand-in-hand with that of the crankshaft to determine the engine’s state.
In case your camshaft is already failing and having issues, then the sensor will report it.
Nevertheless, the sensors can get damaged as well. Causes of this can be wear and tear or just a faulty breakdown. When these sensors get spoilt, certain features occur:
- Your vehicle might not start properly
- The drivability of your car becomes shaky
- The error that indicates you check the engine’s light
Camshaft Problems & How to Avoid/Fix them
Contrary to what some people think, most issues with camshaft for small block chevy are not manufacturer’s error.
Instead, issues like lack of proper installation techniques and broken cam parts are often the causes.
The following is a list of some of these common camshaft problems and their causes.
1. Applying Old Lifters on New Cams
The main caution here is to avoid putting old filters on new cams. Interchanging lifters for different cams is not also appropriate. In case you get it mixed up, the best thing is to replace and install new lifters.
2. Lobe Wear
The significant cause here is the use of the wrong lubricants during installation. Hence, it is advisable to apply only the manufacturer’s choice lubricant to the cam lobes, distributors, and camshaft gears.
3. Broken Camshaft
Having loose rotating parts in an engine is bad and might result in the camshaft being broken by another rotating part.
Broken camshafts can also be caused by rough handling during purchase or installation.
4. Distributor gear wear
Using high-pressure oil can often lead to a reduced lifespan of the cams and distributor gear.
Wears in this distributor gear can be avoided by implementing a maximum up and down distributor shaft movement of 0.010.
Asides from the listed ones, other possible camshaft problems/causes include incorrect valve spring pressure, improper break-in methods, mechanical interference, and excessive-end play.
FAQ’s Small Block Chevy Camshaft Selection
1. What is the advantage of choosing the right camshaft?
If the engine is the door of a house, then the camshaft is the key to unlock it. So, picking the right camshaft for a small block chevy is essential to obtaining improved performance and optimized fuel usage for your automobile.
You’ll also be getting a balance of improved torque and horsepower.
2. What is the difference between the small block and big block chevy?
As the name implies, a small block chevy is lightweight and smaller than the big blocks. They also have shorter strokes piston movement too.
Compared to the big block chevy, their weight improves their handling and accelerating speed.
On the other hand, a big block chevy weighs more, has larger valves, bores, and generates more power.
3. Are camshafts and crankshafts the same thing?
NO! They are different. As you probably know by now, the camshaft is above the cylinders and connected using a timing belt to ensure proper opening/closing of engine valves.
However, the crankshafts are found below the cylinders instead. They convert the up-and-down piston’s movement into rotational motion for the flywheels.
This rotational motion then helps in achieving complete torque conversion from the internal combustion engine.
4. When can we say over-camming has occurred?
Your car is probably over cammed if the valve begins to open too wide and takes extra time before closing. As a result, compression losses occur and affect the fuel/air ratio.
5. What is the best camshaft for small block chevy?
As we already discussed, the best choice of the camshaft for small block chevy will be dependent on what you plan to use the engine to do and other important factors.
However, the COMP Cams CL12-600-4 Thumpr 227/241 Hydraulic Flat Cam and Lifter Kit for Chevrolet Small Block should do.
At 107 cam degrees, the lobe separation angle is enough to ensure that the exhaust gases do not enter the intake valves. This camshaft also works with manual and automatic transmission gears as well.
While the selection criteria for how to choose a camshaft for small block chevy is not so straightforward, you’ll agree that it’s not as difficult as it seems.
The end goal is what matters, and that is having a higher performance engine which is one that depends on how you intend to use it.
So, rather than staying there confused as to what camshaft you’ll get, pick a sheet of paper and jot out the characteristics you want.
Compare it against your budget and expected performance. Do you have suggestions or questions that need more clarification? Do not forget to write to us in the comment section.