Are head and cylinder gaskets compression gaskets? Options

[stevegm]

I need to remove the heads off of a newly rebuilt engine (4-cylinder) I built (never run). They have already been torqued. Are the head gaskets and gasket between the cylinder and block, compression gaskets that should be thrown away (i.e., replaced with new one) after I untorque the heads?

The head gaskets will be easy to replace. But I'd have to pull the cylinders to replace the ones between them and the block.

[N_Jay]

Thoughts!

Lapping barrels to heads:

Since the materials are significantly different in resistance to abrasion (what lapping is doing) most all the wear (lapping, polishing) will be on the softer material of the head.

Lapping valve makes sense because the materials are of similar hardness, and they rotate in operation so you ant a surface the seals at any position in the rotation.

So lets take three different assumptions.

1) Machine marks in the sealing surface of the barrel are concentric.

Lapping the head slightly polishes the barrel, while shaping the matting surface to match these concentric marks. - Yielding an
improved seal.

2) Machine marks are not concentric; perpendicular, axial, or even random.

Lapping the head polishes the mating surface to near flat (average of random barrel surface), and slightly polishes the barrel, yielding a slightly improved seal.

3) Machine marks are radial or spiral but not concentric;

Lapping again polishes the head to near flat depending on the degrees of rotation. Example, machining with a slow spiral pattern and a relatively small rotation (less than 1/4) would actually cut matching groves into the head. In this case the seal is only improved if the head and barrel are assembled near the mid point of the lapping rotational arc.

(Not arguing, just thinking)

Obviously gaskets have their own issues, especially with the high temperatures and relative motion (Difference's in expansion, of heads barrels and studs, etc.)

I wonder what would happen if you machined a slight grove into the top of the barrel (decreasing the surface area and therefore increasing the contact force) and use a o-ring shaped deformable gasket to make a secondary seal?

[Mark Henry]

I wonder what would happen if you machined a slight grove into the top of the barrel (decreasing the surface area and therefore increasing the contact force) and use a o-ring shaped deformable gasket to make a secondary seal?

Porsche totally deleted the head gasket/ring by the 3.2... (IMG:style_emoticons/default/huh.gif) OMG the 3.2 /6 has no head gasket! The horror!
Must be their worst engine. (IMG:style_emoticons/default/poke.gif)

[N_Jay]

I wonder what would happen if you machined a slight grove into the top of the barrel (decreasing the surface area and therefore increasing the contact force) and use a o-ring shaped deformable gasket to make a secondary seal?

Porsche totally deleted the head gasket/ring by the 3.2... (IMG:style_emoticons/default/huh.gif) OMG the 3.2 /6 has no head gasket! The horror!
Must be their worst engine. (IMG:style_emoticons/default/poke.gif)

You seem to miss the point that "designing in" or "designing out" a head gasket is a DESIGN issue.

Machining, materials, and assembly specifications all come into play.

EDIT:
This takes me back to working in a chemistry analytics lab at school.
We had machines that needed very high and very low pressure seals at very high and very low temperatures.
Most common seal was two machined flat surfaces and a gold wire as an o-ring. (That, and lots of bolts for even tension.)
Some has a grove for the wire, some did not. (all specified a real gold wire o-ring, but the school was cheaping out.)

[Mark Henry]

I wonder what would happen if you machined a slight grove into the top of the barrel (decreasing the surface area and therefore increasing the contact force) and use a o-ring shaped deformable gasket to make a secondary seal?

Porsche totally deleted the head gasket/ring by the 3.2... (IMG:style_emoticons/default/huh.gif) OMG the 3.2 /6 has no head gasket! The horror!
Must be their worst engine. (IMG:style_emoticons/default/poke.gif)

You seem to miss the point that "designing in" or "designing out" a head gasket is a DESIGN issue.

Machining, materials, and assembly specifications all come into play.

EDIT:
This takes me back to working in a chemistry analytics lab at school.
We had machines that needed very high and very low pressure seals at very high and very low temperatures.
Most common seal was two machined flat surfaces and a gold wire as an o-ring. (That, and lots of bolts for even tension.)
Some has a grove for the wire, some did not. (all specified a real gold wire o-ring, but the school was cheaping out.)

I'm done, you guys know way more than us unedumacated grunts will ever know.