I need some info on the Before TDU for the intake cam and after TDC for the exhaust to use the double dial indicators. What is the degrees for each cam. I called digidix and he replied all cams are different and Porsche will not give him the info Anyone out there have the info. Please help going back together Jim

 

My 996 Turbo factory workshop manual reference gives the following:

Valve timing with 1mm valve travel and zero clearance (kinetic clearance of the operating plunger taken into account, basic inlet camshaft setting early)

Inlet opens at 10 degs. before TDC.
Inlet closes at 20 degs. after BDC.
Outlet opens at 41 degs. before BDC.
Outlet closes at 9 degs. before TDC.

I'd recommend you get some kind of confirmation before you fire up the engine with the above timing applied.

While I see nothing wrong -- at least from a quick glance -- with the numbers, cam timing is not something one wants approach with anything but the known correct numbers.

 

Be careful here. Many things need to be considered. Cam timing is a simple task, as long as you understand what you are doing and what is required.

There are special fixtures that Porsche sell to time these engines. The 996T is different to the 997T engines. Both use an actuator on the Intake cam but these are different and require different ways of timing. The 996T engine is more in line with most engines when it comes to timing the cams. You do one side of the engine then turn the engine 360° and do the timing on the other side. The 997 you can time the cams at TDC # 1 on both sides. The 996T uses an actuator that requires you to turn it back against itself before you lock down the bolt. The 996T actuator has something like 32° of span from full retard to full advance where the 997 has something like 52°.

Not sure exactly what you are doing with the Indicator dials either. If I understand and assume, are you setting the lobe centerlines or lift at TDC. Easy on the exhaust cam as this is fixed but the Intake is adjustable. You also have to make sure the indicator is on the tappet and not sliding across the face of the tappet as you move the tappet. The easiest way if you are splitting the lobe centerline is to do it on the “backside” of the Lobe. In other words, have the indictor with a flat or radius end on the lobe nose with the cam pointing away from the tappet, valve closed. This is the same, just 360° either side of full open. Just make sure the indicator is aligned with the valve stem, itself. If not, the timing will be off.

If this is a street engine, I suggest you borrow the fixtures and make life easy for your self. Make sure the actuators are fully on their stop before tightening the bolt. Do the 1-3 side first, then turn the engine 360° and then do the 4-6 side. Hope this is helpful

 

Thanks for the help I went a head and bought all the tools plates ect. I was just really wanting to time the car in a exact way instead of a cookie cutter one size fits all. I just couldnt believe Digidix doesnt have the specs to use there product with the different cars. I called them and was told Porsche dont like to share cam specs. He wanted me to check my cam timing before tear down ????? and use it to reasemble. (not a good recomendation) What if the timing was off to start with??? Well I fell into the groove and went the factory way, sometimes thats the best way. Jim

 

So often the simplest way is the better way. This is certainly an area of the engine you can over trick.

I can tell you from my own experience, the factory setting tools are not accurate if you wish to have the centerlines exact. Add in the control of the Intake actuator and it all gets cloudy. However, for a street engine it is good and the advantages the system gives over a fixed system of control is far greater and well worth it.