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Posted by: BMXerror May 3 2008, 09:12 PM

Well, anyone who's used them? Does the arrow point up or down?
Mark D.

Posted by: SLITS May 3 2008, 09:53 PM

Call the doctor .... he'll know ... available 24/7





I would hazard a guess, but I don't want to be wrong and ruin your engine.

Posted by: McMark May 3 2008, 09:59 PM

The piston industry standard is to make a mark that points to the flywheel. Are these the pistons with the valve relief pocket? If so, the pocket does DOWN, regardless of anything else.


Attached image(s)

Posted by: BMXerror May 3 2008, 10:05 PM

No, they're basically 1.7 Euro stockers, but the arrow points up or down? WTF?
Mark D.

Posted by: SLITS May 3 2008, 10:13 PM

Are there any other markings on the piston crowns?

Posted by: brer May 4 2008, 11:34 AM

pics?

Posted by: Headrage May 4 2008, 11:55 AM

Look inside the pistons and see if there is a little crank looking mark. Kinda looks like a zig-zag with a straight line at one end.

Posted by: BMXerror May 4 2008, 12:22 PM

Only the mystery arrow and a number (89.95). I'm guessing it's either weight or bore. No marks on the inside either except an AA logo cast into one side. BTW, what's the difference? Is the wrist pin hole offset or something? I'm emailing AA today, but I probably won't hear from them 'till tomorrow.
Mark D.

Posted by: BMXerror May 4 2008, 12:26 PM

Pic.

Mark D.

Posted by: brer May 4 2008, 09:18 PM

only AA can help you me thinks.

Posted by: tod914 May 5 2008, 01:05 AM

Is it possible the arrows where removed and put on a 6 cyl set?

Posted by: hot_shoe914 Sep 22 2011, 03:08 PM

Bumping this for someone.

Posted by: hot_shoe914 Sep 22 2011, 03:24 PM

Here is my question. If the pushrods are on the bottom, the rockers in the middle, then the valves are up top, shouldn't the valve relief need to be up top also?

Posted by: draganc Sep 22 2011, 08:34 PM

Mark, can you elaborate on your comment? I was told that the arrow always points to the exhaust.

How would the arrow/mark point to the fly-wheel on our engines?

Not to be a smart-ass, just curious.

Posted by: Dr Evil Sep 22 2011, 10:02 PM

The arrows above point up and down. That is not the norm. The norm is fore and aft. The flywheel is on one of those points and the arrow fore or aft woudl point to the fly wheel.

Posted by: biggy72 Sep 23 2011, 12:17 AM

I know the arrow always points toward the exhaust on Stihl products. That's what I have the most experience with. It may or may not be correct in this instance though.

Posted by: draganc Sep 23 2011, 03:47 PM

doc, but wouldn't that flip the pistion by 180deg from "left" to "right" side. i.e. if my left bank points to the flywheel, i would have to flip the pisiton by 180deg on the right side in order to point to the flywheel.



d

Posted by: Dr Evil Sep 23 2011, 04:12 PM

Yes, one would have to flip the pistons to point all in the same direction. If this conflicts with the piston pocket orientation (if there are any) then you have 4 of the same side. Not good.

Posted by: Series9 Sep 23 2011, 06:22 PM

I'm looking forward to this answer.

I've seen arrows both flywheel and nose, but never up or down.

Posted by: r_towle Sep 23 2011, 06:42 PM

measure the wrist pin placement to see if it is centered in the diameter of the piston.
If it is offset (somewhere around 8mm) that would be the bottom of the piston on a stock motor....and the top in a race motor...lol

If they are offset, you want the rod closer to the bottom of the motor...I hope that makes sense.

Makes it quieter with less piston slap when it reverses direction.

Early 911 had this...then it went away..then it came back again.
beetle and 356 and type 4 have the offset pins.

Rich

Posted by: Krieger Sep 23 2011, 07:09 PM

On a map arrows point to North. On pistons they point to the flywheel.

Posted by: hot_shoe914 Sep 24 2011, 07:03 AM

Well, I don't know about the arrows other than I was told they always point towards the flywheel. On these particular pistons with the valve relief, I called AA who made them. The fellow told me that they put the valve relief in rather than make them with the offsets. The valve relief ALWAYS goes down as Mark stated earlier.




Shoe