Piston Protrusion Measurement

[ein bora]

I have read on here enough to know that I need to measure the piston's protrusion before assuming what head gasket to get. This has been frustrating as every time I take a measurement I seem to get a different reading. I've cleaned both the deck and the pistons, but I do believe the quality of my dial gauge or my technique maybe an issue.
However - on the majority I am getting a reading of 77 mm. The old gasket is a two notch, so does this match up correctly??
I do have a brand new one notch and I was hoping to use it, but it seems thicker than the two notch.
Which has left me totally confused.
Also stamped on the pistons is 1.9 UD and 79.48 DN, anybody know what all that means.

Any help appreciated. Thanks in advance.

[R.O.R-2.0]

I have read on here enough to know that I need to measure the piston's protrusion before assuming what head gasket to get. This has been frustrating as every time I take a measurement I seem to get a different reading. I've cleaned both the deck and the pistons, but I do believe the quality of my dial gauge or my technique maybe an issue.
However - on the majority I am getting a reading of 77 mm. The old gasket is a two notch, so does this match up correctly??
I do have a brand new one notch and I was hoping to use it, but it seems thicker than the two notch.
Which has left me totally confused.
Also stamped on the pistons is 1.9 UD and 79.48 DN, anybody know what all that means.

Any help appreciated. Thanks in advance.

so this is an AAZ/1.9 block?

i just throw a ruler over the pistons, on edge, and use a feeler gauge to check protrusion.. and i use the highest reading..

1.6 has a 77.48mm bore, 1.9 has a 79.48mm bore..

[ein bora]

so this is an AAZ/1.9 block?

Yup - sorry 1.9

[745 turbogreasel]

If you get different heights between pistons, a rod is probably bent.

[ein bora]

Thanks guys. Much appreciated.
And no nothing is bent, engine worked fine. Just starting my passat gas to 1.9 idi conversion and this motor came out of my doner car. I have the cam, I have the vnt turbo, I have the cooler, I have the ported and polished head, I have the giles pump, so want everything else to be just so.

[blackdogvan]

When you say the 1 notch is thicker than the 2 notch are you comparing the new 1n to a used (crushed) 2n?

[ein bora]

When you say the 1 notch is thicker than the 2 notch are you comparing the new 1n to a used (crushed) 2n?

  Yes - but I have since mended my ways.

[745 turbogreasel]

And no nothing is bent, engine worked fine. Just starting my passat gas to 1.9 idi conversion and this motor came out of my doner car.

And you know that car never had a valve  crash or  headgasket hydrolock?
A little bend in a rod  won't affect engine feel till one day...