Set Cam timing 911 SC 1980!

[Peveland]

Hi

I have a 1980 911SC that i´m fully rebuilding.
Now I have come to the stage that I need to set the Cam timing.

What I have read is that only 1980 SC has a different Cam timing compare for example earlier and older modells.
Of course I have a book and watched multiple you tubes about the procedure. but non was a 1980 modell?

What i think is correct! i have set my CAM-timing to between 1.4mm and 1.7mm (1.55mm) TDC but now i read it shall be BTDC?

Can someone guide me if this is correct and also how do I set it BTDC? I assume i use te BTDC mark on my crank pulley.
BTW! I have all the right tools.

Many Thanks
Patrick

[Matt at Pelican Parts]

Hi Peveland,

I looked through some how to articles and found one on setting cam timing here:
https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/15-Cam_Timing/15-Cam_Timing.htm

In the article it states:

On the 911SC type 930/10 motor, this value of intake valve stroke in overlapping TDC with 0.1mm valve clearance must be set between 0.9mm and 1.1mm

[Peveland]

Originally Posted by Matt at Pelican Parts

Hi Peveland,

I looked through some how to articles and found one on setting cam timing here:
https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/15-Cam_Timing/15-Cam_Timing.htm

In the article it states:

Thanks Matt

Yes i´ve read that, but unfortunately it´s not written for a 1980 SC. i really want to be sure my cams are supposed to be set at 1.4mm - 1.7mm on indicator dial, and aldo with 6 degree BTDC?

[Walt Fricke]

You are overthinking this. All the 3.0 and 3.2 cams are ground the same, so when it comes to the engine starting and working fine, you can use any of the various specs, depending on whether you want to favor a bit torque, or a bit HP. Or you can take Bruce Anderson's advice from his book and set them in the middle of all the SC specs you can find, which is what Bruce said Porsche did with the 3.2s after it went back and forth.

And you don't set cams at BDC - you set cams at TDC for #1, then rotate the crank and set #4 at its TDC. Where did this BDC notion come from? I suppose you could set both at BDC, and then adjust the distributor or the plug wires 180 degrees off of normal and the engine would run fine? But why?

The 6 degree BTDC has to do with spark, not cams and valves. For the cams you only use Z1.

[Alan L]

My SC is 1.7mm. That is opening of the intake valve at TDC.
That is how they are normally done. So the valve should be opening as you approach TDC. At the point you hit TDC, the dial gauge should read 1.7. Yes - you have a bit of leeway either side of 1.7 - depending what you want. But make both sides the same. Set one and the other should be within 0.1mm at most of the first. So you set #1 intake, then #4
Alan

[Peveland]

Originally Posted by Alan L

My SC is 1.7mm. That is opening of the intake valve at TDC.
That is how they are normally done. So the valve should be opening as you approach TDC. At the point you hit TDC, the dial gauge should read 1.7. Yes - you have a bit of leeway either side of 1.7 - depending what you want. But make both sides the same. Set one and the other should be within 0.1mm at most of the first. So you set #1 intake, then #4
Alan

Thanks Alan

Then i did correct, but i set both to 1.55mm as I read it was some what a golden middle point.

Thanks / Patrick

[boyt911sc]

Patrick,

What engine type is your motor? What cams do you have? Your cam timing would be determined by the kind of camshafts and engine type.

Tony

[AndrewCologne]

Originally Posted by Peveland

What I have read is that only 1980 SC has a different Cam timing compare for example earlier and older modells.
Of course I have a book and watched multiple you tubes about the procedure. but non was a 1980 modell?

The logic is simple, ... US 3.0 engines with larger ports come with 0.9-1.1 cam timing setting, means till 1979 but with a 1980-83 model engine 930.07 & 930.16 with small ports you want the factory default of 1.4-1.7. With this small port engine types this factory cam setting gives you more torque at mid revs.
If you have a ROW 3.0 engine with bigger ports, you'll benefit from a 0.9-1.1 setting. This is factory default on 930.10 204 Hp engines but also a clear recommendation for older ROW engines coming with 180 and 188 HP cause they also where built with bigger ports as well.

[Peveland]

So now im done, My engine is a 930/09 so I set my timing to 1,55mm on both sides.
Thanks for all the help.

Many Thanks
Patrick