Okay, so choosing the right camshaft is one of the most important things you can do when building your engine. As we’ve learned in part 1, if you choose the wrong one, it could be detrimental to your engine. In fact, some gear heads go as far as to say that the camshaft is the foundation of the entire car.

Unfortunately, choosing the correct one for your application is not an easy task because there is a good amount of science that goes into it.

Let’s start out by going over what you shouldn’t do, and why:

A lot of guys (especially if they are new to the hot rod scene) look through a catalogue, pick out the camshaft with the biggest numbers and think they’ve got no more work to do. Wrong answer. I’m guilty of this. I’m going to be totally transparent with you here. For the first performance engine I built, I picked out the camshaft with the highest lift I could find. Thankfully, the guys over at Comp Cams gave me a wakeup call and informed me of my ignorance.

In my gearhead infancy, I thought that a lumpy idle meant more power. And while that is true to an extent (because the valves are flowing more air), if that lumpy idle doesn’t fit with the rest of the car, it won’t work.

I was then informed that this is the most common mistake made by people in the market for a new camshaft. People just don’t know any better.

What made it even worse for me was the fact that I was building a computer controlled LT1 engine from a ‘93 Camaro. Here’s a tip: a cam with huge numbers can really throw a computer out of whack. At some point (usually after 210 degrees of duration), the intake vacuum begins dropping which can cause a whole mess for your computer to figure out.

So, how do you choose the correct camshaft?

There are a couple of things you need to consider. As I stated in Part 1, you need to figure out what you want your car to do. Is this engine only going to be used on the strip? Or, is it going to be dual purpose? This will greatly impact which cam you choose, because you use a totally different set of parts (for example, higher stall, steeper rear end, etc.) for race engines.

(This is actually a combo of blower surge and an enormous camshaft)

This leads directly into the second part: what type of other parts will you be using? Based on what you want your car to do, you’ll choose which type of parts you’re going to use. For example, you don’t plan on driving your car on the street that often. Maybe you’ll just be going to the local cruise nights and car shows with it.

But, its main purpose is for the drag strip. So, it won’t be that big of a deal if you use a set of really steep gears that wouldn’t be streetable on a regular basis.

I’m not going to choose your camshaft for you. That would be stupid, and if we made a mistake, you’d own us. Not to mention the fact that there are literally hundreds (if not thousands) of different combinations.

So…no.

But, what I can do is guide you towards making the right decision. I can arm you with the right knowledge so you can call your cam supplier and give them the info needed to get you on the right path.

To choose the best cam for your total package, you need to know:

• Engine type – For example. Is it an LT1, LS1, L98, 352 FE, 351 W, carbureted big block etc.
• Engine displacement – If you don’t already know this, why are you even here?
• Transmission type – automatic or manual? It matters…
• Intake flow – Carburetor CFM. Or if fuel injected, is it a stock intake?
• Compression ratio – If your engine is stock, this is easy to figure out. If not, we’ll get to this some other day.
• Gear ratio – The drive gears in the rear differential. The higher the number, the faster the launch and drive time over short distances. Also, the higher the number, the worse it is on gas.
• Stall speed – If you’re driving an automatic trans, how high is the stall speed? It matters (a lot, actually).

As you can see, a lot goes into the selection of a camshaft. If all you’re planning on doing is replacing the cam, and keeping everything else stock, the process is fairly straight forward. And, you can actually add a pretty good amount of power to a stock engine just by upgrading the camshaft, valves and springs.

I’m going to include a few more resources that go into some other aspects of choosing a camshaft. Some of this will tell you what camshaft to buy if you have a 350 small block with a 750 carb, a 4400 stall with 3:55.1 gear ratio. These are great resources, but the best idea is to take note of what we spoke about above, and contact your cam supplier to discuss the best route to go. Trust me when I say they are willing to help you out.

Resources:

Super Chevy

Hot Rod Mag

Comp Cams