Choosing a Cam: Passing the Learning Curve

Amongst us gearheads, there’s a lot of good knowledge and there’s a lot of misinformation. When it comes to changing your cam, or really making any performance modification to an engine, the stakes get raised and there’s much more technical knowledge to digest. Which means wading through and knowing what is true and what’s a load-of-bull gets far more difficult.

Although I did my best to wrap my brain around the basics when I embarked on rebuilding my Studebaker’s Small Block Chevy, I made a huge misstep when it came to my cam. You see, Studebaker’s drivetrain got picked up out of another fella’s abandoned Studebaker project. I never knew exactly what was in the engine… just that it was mean and seemed to be built for the drag strip more than daily driving and definitely seemed to have an aggressive cam.

Too Aggressive of a Cam for Your Engine Means:

1. Poor gas mileage
2. Missing cylinder detonations (a.k.a. “lopey” idle)
3. Poor throttle response and low-end power (a.k.a. no winning streetlight drag races!)
4. Increased wear and tear on engine components

When I embarked upon #OperationStude engine rebuild, I knew I needed to tone down my engine parts and make it more suitable for daily driving. While “daily driving capability” doesn’t sound very sexy – in reality my car will be funner to drive, I can finally funnel some money toward other projects and I can hope to one day smoke someone at a stop light. (Because truly, can you even imagine a better sleeper than my Studebaker?!?)

What I Did Right, What I Did Wrong

So during the rebuild I swapped Studie’s hi-rise single-plane intake manifold to a low-rise dual-plane one and the carburetor from a massive 770 cfm to a mild-performance 600 cfm one. That’s what I did right. But the cam? The cam I kept. Wrong! Why? In my still-growing car knowledge I failed to piece together the inter-connectivity each engine component has on the other. While my original engine didn’t fit my purposes, at least the parts fit each other.  After I rebuilt it with a milder intake and carb, those changes accentuated my cam characteristics and created an essentially “un-tunable engine,” I pulled zero vacuum at idle.

As devastating as it was to find out that just after wrapping up my very first engine rebuild I’d have to dive into the engine internals once more, it was an answer to what ailed me and just one more opportunity to learn. Besides, I was now experienced in removing and inserting a cam… so no sweat on doing it once more! What did make me sweat though was choosing the cam I wanted to use.

While the carburetor change was mostly just plugging numbers into an equation and the intake change was a no-brainer, the cam choice seems to carry with it a little bit of voodoo magic that many car people don’t really understand. I was petrified of having to make a choice myself, but stubbornly insistent that I was not going to just ask an expert’s opinion – I knew cam dynamics was something I needed to have in my knowledge aresenal to keep growing in my mechanical skills.

Learn First, Make a Choice Second

So what did I do? I asked a few friends for their expert advice on guiding me towards what I needed to know in order to make a choice of my own. I then conducted a whole lot of my own research – reading articles on topics from choosing a cam to understanding valvetrain dynamics. Then I started looking at cam specs from various companies…

Looking over numbers such as lift, duration and lobe separation angle, I battled the feeling that my brain was turning to Jello. But I pressed on and researched* some more. What I originally assumed would be a couple evenings worth of effort, spilled into a few weekends of research. Pages of notes later and I was finally ready to look at cam specs once more…

This time it felt like I was getting somewhere.

*Some of the most helpful articles I found online to learn about camshafts were:
– Comp Cam’s tech pages ( specifically here and here)
– this long article from David Vizard/Chevy DIY

Comparing specs was finally making some sense to me in order that I could interpret what various companies called their mild, street-to-strip, or race parts lines. Knowing what stock SBC engine and valvetrain specs were helped too.  I could picture what certain cam spec changes would mean in a working engine – much like when I took biology during college and could finally comprehend all that was happening with our cardiovascular systems during a single. split-second. heartbeat. (It’s amazing you know.)

All the while, I’d been jotting notes on cams I thought might be a good fit for Studie’s Small Block Chevy. It was like a game of Goldilocks – cams seemed either too hot or too cold, too aggressive, or not aggressive enough. Finally I found one that felt “just right.” I looked at it’s specs in comparison to some other possible choices I’d written down – and suddenly, I just knew it was the right one.

Passing the decision by Mr.Mechanic Husband as well as my cam “Yoda” Jeff Abbott (many thanks to you Jeff!) and I’d confirmed that my gut was correct! The next day I was on the phone with Lunati ordering parts. A confirmation with their phone tech regarding my choice was another vote of confidence. While I could have just asked knowledgeable friends for recommendations (or posted on the ever-popular car forums… eek!), I can’t tell you how amazing it felt to come to a decision on my own. Sure, it took awhile and ate into my tight deadline of getting my car fixed for a car show, but it’s the right thing to do. I’m now armed with valuable knowledge that will enable me to continue growing in my building-a-badass-car-by-myself skills!

So what cam did I choose? I’m not going to tell you just yet… Coming soon: “A Few Cam Basics”