Cam It: Three Big Tips For Camshaft Selection

The camshaft that you select for an engine is going to have a massive impact on how it performs. You can easily neuter the performance of an engine with the wrong camshaft. So, how should you approach picking the cam for your next engine build? We talked with Eric Bolander from Howards Cams to learn what information you need to have ready before you order a camshaft.

You can think about the different parts of an engine and their jobs sort of like different parts of the human body. The crankshaft is the backbone of the engine, the intake manifold acts like the lungs, and the cam is the brain of the operation because it controls when events happen in each cylinder. Now you can see why it’s so important to pick a camshaft that will be able to properly time and control your engine’s combustion events.

It can be easy to get lost in a sea of camshaft options. The information you arm yourself with will act like a compass and help you navigate those waters.

Tip 1: Research And Planning Are Your Friends

It’s a bad idea to try and pick a camshaft without doing any research about the engine you’re building. You’ll hear people say “an engine is one big air pump”, which is very true, but it’s also a complicated air pump. The camshaft you select needs to work with your entire combination. Actually, more than the engine specs need to be considered when selecting a cam.

“Before you make a decision about a build or a camshaft, do your research on the particular quirks and problems you will run into with that engine platform. Find out what parts of the block or heads need special attention. Check those inherent problems and/or issues with your build against your willingness to correct them, before you get started,” Bolander says.

It helps to have an idea of what your engine is capable of when you're looking at cams.

You’ve got a block, heads, rotating assembly, intake, and a general idea of what your horsepower goal is, now what? It’s time to start coming up with a plan on how to bring it all together and pick a camshaft. You could just take a somewhat-educated guess based on what other people have used, but that isn’t a good course of action. There’s plenty of variables between builds that make simply using what others have, a risky proposition.

The solution is to seek professional help from a company that manufactures camshafts. There’s a lot to take into consideration when trying to figure out what camshaft will work with a combination. Whether there’s a power-adder being used, how the vehicle will be used, what transmission are you bolting up to the engine, and so many other things need to be accounted for when spec’ing a camshaft.

“Before you call, find a camshaft recommendation worksheet and fill it out. Every cam company has one and they’re in the back of almost every camshaft catalog ever printed. The questions are all pretty universal. If you see a question on the form that you don’t know the answer to, find it. The more thorough you are with that form, the better your camshaft selection is going to be. Have that form in front of you when you call. That way, when you’re asked a question about your combination, you’re ready. It will make it easier for the person working with you as they help find the right camshaft for your application,” Bolander explains.

Not every engine is going to be high-horsepower beast.

Tip 2: Be Realistic And Stick To Your Plan

In the real world, you need to be ready to make some compromises with your engine build. These compromises can spring up from budget restrictions, how you plan to use your vehicle, or technology problems. This also circles back to your goals and plan. There’s going to be some tradeoffs when it comes to what camshaft you end up sliding into the engine.

“Everyone wants an engine that will make 1,000 horsepower, spin to 7,500 rpm, be good as a commuter car get 25 miles to the gallon, and be maintenance free. But that just doesn’t happen. You have to decide how you want this engine to behave and function. A super aggressive camshaft might sound good and perform well, but it might not be good for a street car. It’s important to understand there’s going to be some tradeoffs with the cam you use based on your application. This unfortunately is a fact, so make sure you’re realistic about what your goals are when selecting a cam,” Bolander says.

When you've decided what route you're going to go with your engine, stick with it, so the camshaft will match those plans. If you change what heads, intake, or power-adder you're going to use, the cam will need to be changed as well.

The last thing you want to do is to start calling audibles with your engine combination after the build has begun, this will have an impact on cam selection and so much more. Changing parts like your pistons, heads, or intake to match a cam you got really isn’t the best course of action.

“Once you’ve done your research, you know how much valve-lift your heads will need, and have bought appropriate springs for the type of camshaft, you have decided what will work with your realistic goals. That’s the right thing to do, stick to the plan you came up with. The wrong thing to do is buy a cam and build an engine around it after you’ve already come up with a plan. If you’ve done proper research and have a good game plan, choosing a cam that ties all the components together is always better than choosing the components to work with some cam you got a deal on at a swap meet,” Bolander explains.

Tip 3: Don’t Treat All Power-Adder Cams The Same

The use of power-adders is more prevalent than ever. Power-adders are fun and can turn any engine into a total monster, but they still require the correct camshaft to be optimized for maximum horsepower. Generally speaking, nitrous, blower, and turbocharger applications all like different camshaft grinds.

“Look at the duration at .050-inch numbers. When you see a cam with a reasonable/normal intake duration and 10 to 12-plus- more degrees of exhaust duration, on a wide lobe separation, you’re looking at a blower or nitrous camshaft. When you see a cam that has a wide lobe separation and the duration at .050-inch are the same, reversed with bigger intake than exhaust numbers, or move the exhaust slightly two to four degrees, you’re looking at a turbo cam,” Bolander says.

The wrong cam for a power-adder application will have a big impact on how the engine performs.

According to Bolander, with the boosted applications you don’t want to get too wrapped up in the valve lift numbers. There’s no reason to completely max out the airflow on the heads since you’re pushing air into the engine.

Now, if you plan on stuffing your engine’s cylinders full of nitrous, that will require a specific type of camshaft grind. When you start looking at nitrous cams you need to really think about how much juice you’re going to spray, and how often you’ll be spraying the engine to get the right camshaft.

“If you’re spraying 150 horsepower or less of nitrous, once in a while, you’re not building a nitrous car. It’s a normally aspirated car that occasionally gets a kick in the butt with spray. As you start creeping up on the spray, a 200 shot or better, then you need to compensate for the nitrous with the cam. You’ll want more duration on the intake to make room for the bigger air/fuel charge, longer exhaust to scavenge the cylinder, and a wider lobe separation to trap the charge. An engine properly set up for a big shot of spray, let’s say 300 horsepower or more, is going to be an absolute dog when it’s off the bottle. That’s something you’ll need to remember when looking at nitrous cams,” Bolander explains.

If you don’t know what you’re doing, selecting a camshaft for an engine build can be scary. Thankfully, you can arm yourself with some knowledge and then reach out to the professionals to get the right cam for your application. If you take the time to plan and research, the process will be much easier and allow you to get a camshaft for your combination that will make plenty of useable horsepower.

Article Sources

About the author

Brian Wagner

Spending his childhood at different race tracks around Ohio with his family’s 1967 Nova, Brian developed a true love for drag racing. Brian enjoys anything loud, fast, and fun.
Read My Articles