Head gasket recommendation

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Duane

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Getting ready to put heads on my new build. Compression will be approximately 12:1,ported W2, 410 X block, .650 lift roller, Race motor only.
My local machine shop has done a nice job with the machining of the block, but the surface finish is not optimal for an Mls Cometic. I see that Felpro and Mr. Gasket now make Mls gaskets that "supposedly are designed to seal rougher surface finishes while still having the benefits of the Mls. I have never had any trouble with the Felpro 1008 blue in past builds, but those builds did not use this much compression. I have also seen a YouTube video by Cometic that stated although they do not recommend it, if you have to spray your gaskets, to use hylomar.
My local machine shop says not to fall into all the hype about surface finish, that they have used Mls all the time without issue.
Will the Felpro 1008 work reliably at 12:1 or is there another option. Will be using studs by the way.
Any input appreciated

Duane
 
1008 and copper GLUE spray is just fine, NOT normal copper spray.
 
How rough is it? can you feel the grooves if you drag your fingernail across the deck,
I do this on all the blocks I'm putting together. I have a thick piece of aluminum milled flat and I put a piece of sticky back 320 grit paper on it and lightly go over the deck to remove any high spots, then you can really see the grooves. I spray the MLS gaskets with copper a couple times then install them. let it set over night and retorque them. Run the motor and retorque them again. they always turn. ARP says you don't have to retorque them, Cometic says no retorque but with aluminum heads they do move around more than iron so they need to be checked every so often anyway.
 
Duane said:
Getting ready to put heads on my new build. Compression will be approximately 12:1,ported W2, 410 X block, .650 lift roller, Race motor only.
My local machine shop has done a nice job with the machining of the block, but the surface finish is not optimal for an Mls Cometic. I see that Felpro and Mr. Gasket now make Mls gaskets that "supposedly are designed to seal rougher surface finishes while still having the benefits of the Mls. I have never had any trouble with the Felpro 1008 blue in past builds, but those builds did not use this much compression. I have also seen a YouTube video by Cometic that stated although they do not recommend it, if you have to spray your gaskets, to use hylomar.
My local machine shop says not to fall into all the hype about surface finish, that they have used Mls all the time without issue.
Will the Felpro 1008 work reliably at 12:1 or is there another option. Will be using studs by

the way.
Any input appreciated

Duane
Click to expand...


If the deck is flat and the head is flat, you've beat 90% of the sealing issue.

I wish rough surface finishes went away decades ago . The old wives tale that the rough surface "bit" into the gasket and it stayed in place better. It is nonsense. It was nonsense then too. The dowel pins hold the gasket in place.

Every surface should be milled to as flat and smooth a surface as the tooling and the rigidity of the machine can do. Think about it. As the engine builds temperature, the block and heads expand at different rates. Even if both are cast iron. It's worse with bimetal engines. As the block and head expand and contract with heat, those ridges you feel with your fingernail wear down. When they do, the fasteners lose tension and you have a gasket failure.

Again, there are thousands of engines out there with a fairly rough surface finish. The best finish is as smooth and flat as you can get it. Most of the time, either the shop is stuck on a rough finish because it's the way they've always done it, or they don't have a machine capable of machining a surface as smooth as it should be.

With your CR, if you don't detonate the hell out of it, a Fel-Pro blue gasket will be fine. Detonate it and you can kiss any head gasket goodbye.
 
brian6pac said:
How rough is it? can you feel the grooves if you drag your fingernail across the deck,
I do this on all the blocks I'm putting together. I have a thick piece of aluminum milled flat and I put a piece of sticky back 320 grit paper on it and lightly go over the deck to remove any high spots, then you can really see the grooves. I spray the MLS gaskets with copper a couple times then install them. let it set over night and retorque them. Run the motor and retorque them again. they always turn. ARP says you don't have to retorque them, Cometic says no retorque but with aluminum heads they do move around more than iron so they need to be checked every so often anyway.
Click to expand...

I did something very similar. Before I started my final wash of the block I used 400 grit wet paper on a block to somewhat smooth the decks of the block. This did somewhat smooth the finish but my profile meter still says not good enough.
I am considering the Felpro Mls or the Mr Gasket Mls because they claim to be engineered more specifically for the rebuild industry.
 
yellow rose said:
If the deck is flat and the head is flat, you've beat 90% of the sealing issue.

I wish rough surface finishes went away decades ago . The old wives tale that the rough surface "bit" into the gasket and it stayed in place better. It is nonsense. It was nonsense then too. The dowel pins hold the gasket in place.

Every surface should be milled to as flat and smooth a surface as the tooling and the rigidity of the machine can do. Think about it. As the engine builds temperature, the block and heads expand at different rates. Even if both are cast iron. It's worse with bimetal engines. As the block and head expand and contract with heat, those ridges you feel with your fingernail wear down. When they do, the fasteners lose tension and you have a gasket failure.

Again, there are thousands of engines out there with a fairly rough surface finish. The best finish is as smooth and flat as you can get it. Most of the time, either the shop is stuck on a rough finish because it's the way they've always done it, or they don't have a machine capable of machining a surface as smooth as it should be.

With your CR, if you don't detonate the hell out of it, a Fel-Pro blue gasket will be fine. Detonate it and you can kiss any head gasket goodbye.
Click to expand...
I read this commentary with interest, 'speically the comment of flatness being most of the battle. The one thing that I question is on the dowel pins; I can't see where they do anything to to help the gasket stay in place in the narrow webs between cylinders. It is just clamping pressure and surface friction that keeps them in place in those areas.

With grinding type surfacers still around, the rough surfaces in rebuilds aren't going away IMHO.
 
nm9stheham said:
I read this commentary with interest, 'speically the comment of flatness being most of the battle. The one thing that I question is on the dowel pins; I can't see where they do anything to to help the gasket stay in place in the narrow webs between cylinders. It is just clamping pressure and surface friction that keeps them in place in those areas.

With grinding type surfacers still around, the rough surfaces in rebuilds aren't going away IMHO.
Click to expand...


You are right in the dowel pins only hold the gasket in certain areas. They have zero affect between the bores, where most failures occur. I'm talking about what they used to call gasket migration, where the entire gasket would move around. Every time a cylinder fires it lifts the head off the block. Every time. And the gasket has to follow this movement or it fails. That's what the dowel pis do after the head is bolted down.

If you control speed and feed, and grinding stone will produce a mirror finish. It is the multiple cutter style of surfaces that have issues. Especially if you have one or two cutters not perfectly located.
 
yellow rose said:
You are right in the dowel pins only hold the gasket in certain areas. They have zero affect between the bores, where most failures occur. I'm talking about what they used to call gasket migration, where the entire gasket would move around. Every time a cylinder fires it lifts the head off the block. Every time. And the gasket has to follow this movement or it fails. That's what the dowel pis do after the head is bolted down.

If you control speed and feed, and grinding stone will produce a mirror finish. It is the multiple cutter style of surfaces that have issues. Especially if you have one or two cutters not perfectly located.
Click to expand...
Thank you; I learned something new on the milling processes.

I ran some rough numbers, and if the typical peak combustion pressures were static (i.e., held forever), then a typical stock SBM head bolt would be stretched a few thousands over the normal torqued-in-place length. Of course, the peak pressures only last a millisecond or less, so that makes the actual movement much less. But I never considered how much it might move the head just from combustion pressures. So thanks for bringing that up.

Here is an article that gives some info on the forces and bolt/stud elongation involved. The numbers mentioned hang with the numbers I was running.
Perfect Engine Sealing Starts With Proper Head Bolt Use - Engine Builder Magazine
 
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