If I'm not mistaken, you start to measure when the valve is opened .050", and then stop measuring when it reaches .050" closing again. My question is, do you start measuring when the pushrod moves .050"...or when the valve itself opens .050"? If it is the valve...wouldn't the dimensions of the rocker affect the statistic? I have 1.5 to 1 rockers...if it was a longer rocker, it would be a longer duration if measured by the valve movement right?

Thanks!

 

Check out this article from Popular Hot Roding. Part 4 of article
http://www.popularhotrodding.com/tec.../photo_04.html

 

I've always enjoyed the vague articles written by PHM. They always throw some stupid S**T at the average Joe that the person eventually adheres to and inevitably hurts them more than helps.

I like the POS formula for the LCA (actually LSA by the old school and is much easier to comprehend). Divide your cylinder CI by your valve diameter and that's what you should be running for your LCA (or LSA for the real people). That's a big load of CRAP to tell people. Do they even consider if you have an AT or MT? The weight of the car? Gearing? The cam I/E duration can affect what the correct LSA should be as well as the port design of the heads.

Good call on the link Pete, but in my opinion, after the lobe diagram and those explanations, the article is flawed. PHR at its best blowing smoke.........

RM