L-n-L Performance Development

February 10, 2020

My name is Lee Atkinson, and I have been a "gear head" for as long as I can remember.  I taught myself to rebuild & tune the carburetor on my 3.5hp Tecumseh powered mini-bike when I was 11.  Over 40 years later, I'm still usually found tinkering with some sort of engine!

In the mid 1980's, I performed my first camshaft change, on my cousin's '78 Trans Am.  A local "expert" sold it to us, telling us how awesome it would run in his car - it SUCKED!  It also started my personal quest to "understand" camshafts.  

The internet did not exist, and even making long distance phone calls was rather expensive at that time - but we needed a better cam for his engine.  I wrote a letter that described the engine/car (engine type, size, compression ratio, intake, carb, exhaust, gears, converter, use, etc.).  We then made a bunch copies of the letter, made up SASE's (self-addressed stamped envelopes, for those younger than about 45) and mailed those to every cam company we found advertising in the back of Hot Rod and Popular HotRodding.

We had about 10 companies reply to us.  Some even included a free decal (I thought Schneider's was the coolest).  Excel did not exist, but I manually drew up a spreadsheet so we could see & compare each cam, gross duration, duration @ 0.050", lift, LSA, etc. I applied the math I knew to determine the mean and median values for the data - knowing that whichever cam was in the center of the data, SHOULD be the best choice.  I still remember, it was the Competition Cams Magnum 268.

We ordered that cam, installed it, and it performed just like we expected!  With a 3.23 posi and the crappy tires we had back then, the car ran easy low-14's, and used the cheapest gasoline we could find.  That event sparked my desire to learn what all those "numbers" actually meant, and how to best pick a cam.  I read every magazine article, every book I could find in the library, and every cam company catalog I could get my hands on.

With the "knowledge" I gleaned from that research, I selected a few cams on my own, and they worked well.  I started helping friends, and they also were happy with my selections.  By the mid 90's, I was on the internet and finding all sorts of real world data - and I started to "see" how duration related to compression ratio, to converter stall speeds that were needed, to engine CID,...  I developed a "formula" that worked pretty well for selecting camshaft specs.

 About a decade ago, I had a few serendipitous things happened.  I bought a chassis dyno.  I made friends with a guy who was doing a lot of LS builds and wanting to test/tune them on a chassis dyno.  And I started using some engine simulation software that Jim Hand (Pontiac people will recognize that name!) had introduced to me.  Before long I was using the software to help the LS guy fine tune his cam selections, which led me to design some custom grinds for him.  The software was VERY helpful, and our dyno results were surprisingly close to what the software predicted!  But, the software also suggested that my "formula" for cam design was leaving power on the table.

For giggles, I let the software guide me on a cam design, based on a build my friend was working on.  The final specifications were NOTHING like anything I had ever ordered, or even seen ANYONE use.  I told my friend about the results.  He was intrigued, and told me to order it, he'd pay for it.  It worked, REALLY well!  That led to several more rather unorthodox cam orders, and several times I had a cam company call me back to make SURE that there was not a misprint on the order :-)  

It was a long process for me to learn about camshafts.  But it was MUCH harder for me to accept that much of what I had "learned" was either wrong or only "accurate" for a very narrow set of parameters.  There is still much I can't effectively explain, and I now I am STILL learning.