We often get the question: "How do I tell which cams are the intake cams and which are the exhaust? Which ones go in the front and rear heads?" We've also had people call about ill-running cars after installing cams or getting a build done, and one question we ask is if the cams are installed correctly.
Making the distinction between the 4 cams in the DOHC (both turbo and non-turbo) is actually quite easy. You can make the determination with the cams in the car or out of the car prior to installation. Each cam is labeled with letters/numbers that cross-ref in the service manuals to what their application is. But even without the manuals, you can easily visually confirm where each cam goes in the heads.
With the cams NOT installed, lay them out with the cam gear side (end with the big threaded hole for cam gear bolt) lined up. Turn them all so the first pair of lobes are facing UP and the second pair of lobes are in the 8 o'clock position (down against table on the left side). The alignment pins for the cam gears will be in the configuration as shown in the picture below - picture is as they are installed in the car from the driver side (looking at the timing belt side of the engine). Just arrange your cams to match the picture! :-)
If the cams are already installed in the heads/engine, you can still easily check if they are in the correct location. The rear ones (long ones) are EASY as the rear intake cam has the 2 notches on the back side as pictured above. The front ones still need another method of confirmation as they don't have the notch.
Looking at the front head with the valve cover removed, correctly line up on the timing marks on the cam gears (before removing the valve cover, obviously, as the timing marks are on the valve cover). The first pair of lobes should pointing up and slightly toward each other like / \ . If they are point up and away from each other like \ / then the cams are installed reversed and you will need to swap the cams with each other. You can leave the cam gears installed as they are the same - the alignment pins position them correctly.
Even without removing the valve cover, you can still quick-check the front cams. Line up the cam gears on the timing marks and remove the oil filler cap. The lobes that are visible under through the filler opening should be pointing UP toward the sky. If they are pointed more forward toward the front of the car, then you probably have the front cams revered and should check closer by removing the valve cover to see better.