Help with Piston Orientation

[911freek]

Hi all,

I am rebuilding the engine using the original set of pistons from Mahle. I decided against the higher ration pistons because the engine is, well, 40 years old.

The pistons have a "hump". IN Wayne's book it says the hump should be pointing "up" - which I take as in the direction of the flywheel. Then some of the pics show the opposite.

On one side (1-2-3), this was the case (I tore it down so took a picture).

4-5-6 was torn down by my mechanic during the diagnosis phase, and hence I am not sure.

Can anybody shed some light on this? Do both sides point in the same direction, which it is etc.?

Thanks!!!

[Spenny_b]

Subject to additional thoughts by the pro's, my understanding of "pointing up" would be that "up"=inlet side (as opposed to exhaust side), I wouldn't be using flywheel rotation direction to determine this

[Flat6pac]

The piston concave area faces the spark plug so installed the concave side is to your right.
Bruce

[911freek]

Thanks!!!
So all domes point to the flywheel. No need to take anything apart then :-)

[E Sully]

[911freek]

I received 4 answers by now, and none is consistent...

So let me ask again:
1. pistons 1-2-3 at which direction (flywheel or timing)?
2. pistons 3-4-5 at which direction (flywheel or timing)?

Its a 3.0L SC engine.

Thanks again!

[Dpmulvan]

Just remember the high spots of the piston go up and to the left.

[mytoy]

Originally Posted by 911freek

I received 4 answers by now, and none is consistent...

So let me ask again:
1. pistons 1-2-3 at which direction (flywheel or timing)?
2. pistons 3-4-5 at which direction (flywheel or timing)?

Its a 3.0L SC engine.

Thanks again!

911freek;

How do you figure that you got 4 differing answers? You are really confusing yourself by this very simple install. The piston can only be put in in 2 different orientations.

1) With the dome up (the correct way)

2) with the dome down (the incorrect way)

Its that simple. If you install all the pistons with the dome up they will be orientated in the correct manner with the dome facing to the left and the recess facing to the right when looking directly at the piston in front of you. It can't be any simpler than that.

In order for you to understand it better we will put it in the terms that you want to complicate it with.

123 will have the dome pointing towards the flywheel side and the 456 will have the domes pointing towards the timing side in a mirror image of the 123 side, just like your spark plugs are orientated.

Your making this much more complicated than what it needs to be.

[911freek]

Finally got it and it conforms to the pics I have seen (each showing indeed a different direction).

Thank you all for the willingness to assist, good advice and... patience.