If you are looking to unlock serious horsepower and that iconic aggressive idle, learning how to cam a car is the ultimate rite of passage for any gearhead. We all agree that nothing beats the mechanical symphony of a high-performance engine, but the technical side of a camshaft swap can feel intimidating for the uninitiated.
This guide promises to simplify the complex world of valve timing and mechanical installation, providing you with a clear roadmap for your project. We will preview the essential tools, the step-by-step teardown, and the critical break-in procedures needed to ensure your engine survives its first start-up with a new profile.
Whether you are building a dedicated track machine or a weekend cruiser, understanding how to cam a car requires patience and a focus on precision. By following these industry-standard practices, you can transform your vehicle’s power band and sound without the stress of a catastrophic engine failure.
Understanding the Role of a Camshaft in Your Engine
Before you pick up a wrench, you must understand what a camshaft actually does. It is often called the brain of the engine because it controls the timing and duration of the intake and exhaust valves.
The camshaft uses egg-shaped lobes to push against lifters or rockers, which then open the valves. The shape of these lobes determines how much the valve opens and how long it stays open, directly impacting engine breathing and power delivery.
When you learn how to cam a car, you are essentially changing the engine’s breathing characteristics. A larger cam allows more air and fuel into the cylinders, which translates to more power at higher RPMs but often sacrifices low-end torque.
Lift, Duration, and Lobe Separation
Lift refers to how far the lobe pushes the valve open. More lift generally means more airflow, but you must ensure your valve springs can handle the extra travel without binding.
Duration is the measurement of how long the valve stays open, usually expressed in degrees of crankshaft rotation. High-duration cams move the power band higher up the RPM range, creating that famous “choppy” idle.
Lobe Separation Angle (LSA) is the distance between the centerlines of the intake and exhaust lobes. A narrower LSA increases overlap, which is the period when both valves are open at once, enhancing high-speed scavenging.
Choosing the Right Profile for Your Build
Selecting the wrong camshaft is one of the most common mistakes DIYers make. You must match the cam to your vehicle’s weight, gear ratio, and intended use to avoid a sluggish driving experience.
For a daily driver, you want a “Stage 1” or “Street” cam that offers a noticeable power bump without ruining your fuel economy or vacuum pressure. Vacuum is vital because it powers your brake booster and other accessories.
Off-roaders often prefer “Torque” cams. These profiles prioritize low-to-mid-range grunt, helping you crawl over obstacles or pull heavy trailers without needing to redline the engine constantly.
Hydraulic Roller vs. Flat Tappet
Most modern engines use hydraulic roller cams. These use small wheels on the lifters to reduce friction, allowing for more aggressive lobe profiles and significantly easier break-in periods.
Older engines often utilize flat tappet cams. These are cheaper but require high-zinc oil and a very specific break-in procedure to prevent the lobes from “wiping” or wearing down instantly upon start-up.
If you are upgrading an older block, consider a roller conversion kit. While more expensive, it offers better reliability and allows you to run modern synthetic oils without fear of internal damage.
Essential Tools and Parts for the Job
You cannot perform a camshaft swap with a basic socket set alone. You need specialized tools to ensure the timing is perfect and the components are seated correctly.
Gather a high-quality torque wrench, a harmonic balancer puller, and a variety of feeler gauges. If you are working on an overhead cam engine, you will likely need specific timing chain locking tools to prevent the gears from jumping.
Do not forget the consumables. You will need plenty of assembly lube, new gaskets, a fresh oil filter, and high-quality engine oil. Using a dedicated break-in oil is highly recommended for flat tappet setups.
- Harmonic Balancer Puller: Necessary for removing the crank pulley on most domestic V8s.
- Valve Spring Compressor: Required if you are upgrading springs to match the new cam.
- Degree Wheel: Used to verify that the cam timing matches the manufacturer’s spec card.
- Magnetic Parts Tray: Essential for keeping track of small bolts and lifters.
how to cam a car: The Complete Step-by-Step Installation
Now that you have your parts and tools, it is time to dive into the physical labor. This process requires a clean workspace and a methodical approach to ensure nothing is overlooked during reassembly.
Phase 1: Preparation and Teardown
Start by disconnecting the battery and draining the coolant and engine oil. You will need to remove the radiator, water pump, and front accessories to gain clear access to the timing cover.
Remove the valve covers and the intake manifold if your engine is a “cam-in-block” design like an LS or a Small Block Chevy. Keep all pushrods and rockers in order using a labeled piece of cardboard or a dedicated organizer.
Rotate the engine to Top Dead Center (TDC) on the number one cylinder. This aligns the timing marks on the crank and cam gears, making it much easier to set the timing correctly later.
Phase 2: Removing the Old Camshaft
Remove the timing chain or belt and the cam gear. Carefully slide the old camshaft out of the block. Be extremely gentle here; the cam lobes can easily nick the cam bearings, which would require a full engine teardown to fix.
Inspect the old cam for signs of unusual wear. If you see pitting or flattened lobes, you may have an oiling issue or a lifter failure that needs to be addressed before installing new parts.
Once the old cam is out, clean the area thoroughly. Use a lint-free rag to wipe down the internal journals and ensure no debris is left behind that could contaminate your new oil.
Phase 3: Installing the New Camshaft
Apply a generous amount of assembly lube to every lobe and journal on the new camshaft. This specialized grease provides critical lubrication during the first few seconds of engine operation before oil pressure builds.
Carefully slide the new cam into the block. Support the weight of the cam as it passes through each bearing to avoid any metal-to-metal gouging. Once seated, it should rotate freely by hand.
Install your new lifters and timing set. Align the timing marks (usually dots or arrows) exactly as specified in your service manual. Even being one tooth off can cause piston-to-valve contact and destroy your engine.
Phase 4: Reassembly and Degreeing
While some mechanics skip “degreeing” the cam, experts recommend it. Using a degree wheel and a dial indicator ensures the cam is opening the valves at the exact moment the manufacturer intended.
Reinstall the timing cover with a new gasket and sealer. Carefully press the harmonic balancer back onto the crankshaft using an installation tool. Never hammer the balancer on, as this can damage the thrust bearings.
Replace the pushrods, rockers, and valve covers. If you upgraded your valve springs, ensure they are shimmed to the correct height. Finally, refill all fluids and double-check every bolt for the correct torque spec.
Why Supporting Modifications are Non-Negotiable
Learning how to cam a car involves more than just swapping the stick itself. A high-lift camshaft puts significantly more stress on the entire valvetrain, requiring upgraded components to maintain reliability.
Stock valve springs are often the weak link. If the new cam has more lift than the springs can handle, they will “coil bind,” leading to snapped valves or bent pushrods. Always buy the matching springs recommended by the cam manufacturer.
You should also consider your fuel system. A larger cam pulls in more air, which means you need more fuel to maintain a safe air-fuel ratio. Upgrading to larger injectors or a higher-flow fuel pump may be necessary for peak performance.
The Importance of a Custom Tune
Modern fuel-injected cars rely on a computer to manage timing and fueling. When you change the camshaft, the factory “map” no longer understands how the engine is breathing, leading to poor idling and potential engine knock.
A professional dyno tune or a high-quality handheld tuner is essential. The tuner will adjust the idle speed, spark advance, and fueling tables to take full advantage of the new cam’s profile while keeping the engine safe.
For older carbureted engines, you will need to re-jet the carburetor and potentially adjust the accelerator pump. You may also need to change the distributor’s advance curve to prevent stalling at low speeds.
Breaking In Your New Camshaft Properly
The first 20 minutes of a new cam’s life are the most critical. If you fail to follow the proper break-in procedure, you can ruin the camshaft and lifters before you ever leave the garage.
For hydraulic roller cams, the process is simple: check for leaks, let the engine reach operating temperature, and vary the RPMs slightly. However, flat tappet cams require a rigorous 20-minute run at 2,000 to 2,500 RPM.
This high-RPM run ensures that plenty of oil is splashing off the crankshaft onto the cam lobes. Never let a new flat tappet cam idle during the break-in period, as low oil splash can cause the metal to gall and fail.
After the initial break-in, drain the oil and change the filter. Look for excessive metal shavings in the oil. A small amount of fine “glitter” is normal from the assembly lube and initial seating, but large chunks indicate a problem.
Frequently Asked Questions About How to Cam a Car
Will a cam swap make my car fail an emissions test?
It depends on the “aggressiveness” of the cam. High-overlap cams allow unburnt fuel to escape into the exhaust, which can increase hydrocarbon levels. Many manufacturers offer 50-state legal cams that provide a power boost while remaining emissions-compliant.
Do I need to pull the engine to install a cam?
In most rear-wheel-drive cars and trucks, you can perform the swap with the engine in the vehicle by removing the radiator and grille. However, in many front-wheel-drive cars, the engine or transmission often must be lowered to gain enough clearance.
Can I reuse my old lifters with a new cam?
If you have a flat tappet setup, the answer is a firm no. Lifters and cam lobes “mate” to each other during break-in. Reusing old lifters on a new cam will almost certainly cause a premature failure. With roller cams, you can often reuse lifters if they show no signs of wear.
How much horsepower will a cam add?
A well-chosen camshaft can add anywhere from 30 to 100+ horsepower, depending on the engine and supporting mods. The biggest gains are usually seen when the cam is paired with high-flow cylinder heads and a free-flowing exhaust system.
Final Thoughts on Mastering the Cam Swap
Successfully completing a camshaft installation is one of the most rewarding DIY projects an enthusiast can tackle. While the process of learning how to cam a car is labor-intensive, the result is an engine that sounds better and performs at a much higher level.
Remember that patience is your most valuable tool. Double-check your timing marks, use plenty of assembly lube, and never rush the break-in process. If you encounter resistance when rotating the engine by hand, stop immediately and investigate the cause before using the starter.
Take your time, follow the torque specs, and enjoy the new-found power of your build. Stay safe and stay comfortable out there on the road or the trail!
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