the pressure band around the cylinder is made up of a slightly thicker
layer, so that this band squishes more, and has a higher pressure than
the rest of the gasket. this is the primary sealing ridge.

if the gasket were uniform all the way across, then the clamping,
theoretically, would be the same all the way across. that isn't a good
situation here.

the sealant applied to the gaskets, the "secret sauce", is crucial
to the gasket mating with the deck and head surfaces.

i've not bothered to look and see what the specification for surface
finish is for this engine, in microinches, but glass smooth isn't where
it's at usually. you need a very fine amount of tooth on the surface.
what is critical is the consistency of the scratch pattern. i'm guessing
something in the area of 8 microinches would be ideal.

personally, my favorite surface, both in terms of flatness, and
scratch pattern, is blanchard grinding. for cylindrical finishing,
the standard for decades has been a sunnen hone.

a rough guide... (pun intended) can be found here:

Surface Roughness (Texture) Review - Engineers Edge

i am surprised that none of the specialty gasket makers have introduced a product line
to address this problem, other than BO. seems that and OEM are the only choices available.
these folks make annealed copper gaskets for top fuel and whatnot, and i'd bet they could
come up with an interesting product.....

https://www.flatoutgroup.com/Default.aspx

 

Get your micrometers or borrow one from someone who has and check the diameter of a 6.0 head bolt you will find it's not 12mm like you claim. 12mm equals .472 14mm= .551 and the 6.4 bolts are 16mm which is .630 dia. Anybody have a used 6.0 bolt laying around that you can measure?

 

LOL the fire ring is to prevent burnout.

 

......... and it does it with compressive force (sealing) and proper materials of construction (as stated)

I would like for you to prove your point .... lets try that approach.

Better yet, call BPD and discuss it with him. IMO the evidence of a weaker design in the BO gaskets is quite conclusive (in the fire ring dimension AND the metal layers) - which was the intent of the post.

 

6.0s are 14mm and 6.4s are 16mm

 

Does anyone have experience with Cometic's MLX diesel head gasket? I know Cometic has a good reputation with the performance crowd.

 

I am glad the bolt size is cleared up, maybe some posters will remember what size Navistar 6.0 and 6.4 head bolts are used. As for BPD, they can't even determine what material the head gaskets are made of (stainless?) just a bunch of thickness layer dimensions. Very informitive.

 

you seem to be informed about metallurgy, mechanical engineering,
and related areas. i'm sure that with all the people on here, we could
get a dead headgasket for you to dissect, and then you'd be able to clarify
this for us.

i don't have the skills to disassemble a 5 layer cladded metal, and accurately
analyze the composition, but i do have the skills necessary to get a specimen
in the mail to you tomorrow. send my your contact information in a private
message, and i'll have one in the mail to you tomorrow afternoon.

 

"bismic has exceeded their stored private messages quota and cannot accept further messages until they clear some space."

somebody didn't take out the garbage......

 

not you too ....................

 

exactly!!

That is the way to add value, rather than detract. I am glad to have the thickness information. Makes sense to me. I would love to have the PMI info also. If someone wants to send me the samples of each, I should be able to have the material identified. PM me if you have samples (hopefully my inbox will be clear - at least I am clear for the moment!).

For me, it seems very easy to accept that if a fire ring dimension is greater on the OEM gasket, that the contact the head makes on it as it is tightened down will occur sooner than it would on the BO gasket. Initially, all the force applied to the heads will be exerted on the surface area it first contacts and the force on that area will remain higher throughout the tightening process (the amount depends on the deformation properties of the material), even though the force will distribute itself as contact is made in other areas. Again - I like having information and will not complain about it just because I would like to have more .........