Head Gasket sizes

[harpy]

I just took apart an engine that I built 10 years ago using a hydro ME block and mechanical head. Finally decided to mate the block to a hydro head since I found a good one. When I measured piston protrusion ten years ago I recorded these numbers which lead me to buy a 2 notch gasket from Jack, and I used those numbers to buy a 2 hole gasket for the hydraulic long block last week. BUT I just saw the FAQ section about deciding head gasket thickness based on piston protrusion.

SO now I'm wondering if I should've been using a 1 notch all along? I had a max protrusion of .812 mm. I can't remember what I referenced before, but I'm wondering if I could've had slightly better performance/compression with a thinner gasket.

Also, I guess it couldn't hurt to re-measure the protrusion, but would it even change much on 50k miles of NA fury?

Posting here for confirmation, validation, negation, etc.

#1 - .029" (.736 mm)
#2 - .032" (.812 mm)
#3 - .032"
#4 - .029"

1986 Jetta 1.6 hydraulic:
* 1-hole (1.53mm): 068 103 383 EH
* 2-hole (1.57mm): 068 103 383 EJ
* 3-hole (1.61mm): 068 103 383 EK

1 notch - 1.53mm thick to suit piston protrusion of .66mm to .86mm
2 notch - 1.57mm thick to suit piston protrusion of .87mm to .92mm
3 notch - 1.61mm thick to suit piston protrusion of .93mm to 1.02mm

[libbydiesel]

I would use the AAZ head gasket on any hydraulic 1.6TD. 

http://vwdiesel.net/forum/index.php/topic,6741.0.html

[harpy]

Oh weird, I was under the impression head gasket sizes were different for AAZ.

I bought Hylomar to use with the fiber gasket. Isn't that a no-no on metal? I had some weeping before so I'm hoping to avoid that this time.

[libbydiesel]

I use hylomar on all of them and highly recommend it.  Use a very light coating of the spray hylomar (not the tube). 

[ORCoaster]

Harpy, use the 1 notch.  That will be your best performer.  Both for power and mileage per gallon.  Do it by the book numbers.  That is what they are there for. 

[WeekendMechanic]

Harpy, use the 1 notch.  That will be your best performer.  Both for power and mileage per gallon.  Do it by the book numbers.  That is what they are there for. 

I would use the stock aaz gasket.
Numbers are like an appendix you don't really need them...

[libbydiesel]

Numbers are like an appendix you don't really need them...

I'm not sure what you mean by that.  The AAZ gasket comes in different thicknesses.  It is beneficial to fit the appropriate thickness head gasket based on piston protrusion. 

[WeekendMechanic]

Numbers are like an appendix you don't really need them...

I'm not sure what you mean by that.  The AAZ gasket comes in different thicknesses.  It is beneficial to fit the appropriate thickness head gasket based on piston protrusion.

You might be right on that but still numbers can change one day its this the other that...

[ORCoaster]

Hmm, The Bentley I own was printed in 1985, those numbers have not changed for head gasket protrusion.  If you want it to run like it was designed, then you best pay attention to the NUMBERS!  German engineering is all about them and they are very sharp about being on spec. 

You can run whatever gasket you like or have on hand, that is your choice.  But I choose to run spec gaskets cause I know they do the job the best.  With 53 HP pulling me down the road, and out of the way of some overbuilt Dodge Ram with a belching black 6-inch exhaust, I need all of them.

[libbydiesel]

You might be right on that but still numbers can change one day its this the other that...

The piston protrusion does not typically change on an engine.  Of course you need to measure it correctly which of course requires cleaning the carbon off the piston crowns.

The specs have not changed.   

[harpy]

We pulled numbers yesterday and they were within .003" of what I recorded ten years/50k miles ago. Granted, I can't remember how I got those numbers last time, but I'm sure the method can affect outcome.

That said, I'm still in the one notch realm. Going to order a one hole hydro gasket so I can get this thing back together this week. I keep hearing AAZ gasket but I've also read plenty of accounts of people having no problems with fiber. Are the metal gaskets just better quality? Holds the boost? no weepage?

I bought this dang can of hylomar and also read that it's not to be used on metal gaskets. I figured that spray would do me good on the fiber gasket and keep the coolant and oil where it's supposed to be.

Side note -- longitudinal engines are sick. SO different, in terms of mounting points and whatnot.

[libbydiesel]

If the gasket surfaces are flat, then the metal AAZ gasket seals better.  They basically eliminate the 60,000-100,000 miles head gasket failures that typically occur with the fiber gaskets.  The spray hylomar eliminates the seeping at the pressurized oil channel or the drains if used with either gasket.

[harpy]

Okay, last question! it seems the one hole AAZ head gasket is NLA, unless someone can point me to one that exists...

SO my choice is between a two hole AAZ gasket and a one hole fiber gasket.

On the one hand, the fiber gasket is the appropriate size and might give me some advantage with compression/power/economy. On the other hand the metal head gasket is considered the better option, but I would be running thicker than what my piston protrusion suggests I use.

Worth re-stating that I unknowingly ran the two notch for 50,000 miles not knowing I should've installed the one. Engine always ran fine.

BUT COULD IT RUN BETTER?

[ORCoaster]

If I had to make that choice I would opt for the thinner fiber gasket instead of the two-hole AAZ one. 

Just my choice, not meant to influence you in any manner. 

[fatmobile]

Right, because the AAZ cylinders are wider.
 So the gasket is too.
The 80mm pistons in the 1.7 TD wouldn't fit through a fiber gasket.
 That means there is even more empty space at the top of the cylinder.
Did you check the dealership for a head gasket?
 I had to order one from them last time,..
they got it out of Canada.
 Took 2 weeks.
Cost about $75.