Cam questions Options

[ThinAir]

I'm assembling the pieces that I'll need to rebuild my 1973 2.0L engine that will retain the stock FI. I'm wondering about cam choices and why I would want to choose a particular one. The only change I've made from stock at this point is that I've got Mahle Euro pistons & cylinders, but they are stock size so there is no increase in displacement.

I hear a lot about the Web Cam 73 and here's the info I've been able to find on how it compares to stock:

Type/Lift/Duration/Duration @ .050
Stock/.392/?/210
73/.426/262/224

Am I correct that Duration is how many degrees both intake and exhaust are open? Or is that called Overlap? If it is called Overlap, does anyone know the specs on the two cams?

What is the difference between Duration and Duration @ .050?

Lift is pretty obvious - the 73 is going to open farther. I assume this means it can deliver more fuel mixture in the same amount of open time compared to the stock lift.

My car is a daily driver that will probably never see anything more exciting than a PCA autocross. So how do I choose a cam and why do I want one or the other?

[Bleyseng]

And that is the problem with using the Djet as the longer duration changes the vacuum signature/VE curve. This ECU is hard wired for a certain engine specs and if you change it much you have some problems. Some have very little problems with the Web 73 others do. Why? It depends on the ECU year near as I can figure out. The 73 is a bastard year where Porsche cobbled together the 2.0L Djet as they could because they couldn't get a new 2.0L ECU from Bosch fast enough. They actually rushed the whole 2.0L engine project to get it to market after the six was dropped. They knew they needed a second more powerful engine for the 914 other than the 80hp 1.7L. The problem with the six was it was just too expensive.

Geoff