Head and Block Machined??

[TONY!]

Yes, both need to be machined to get an RA of lower than 50 for Cometic (as their tech staff recommends) and even a lower RA for some other HG makers.
Lower RA's = smoother surfaces. It is not like with sand paper ratings: with RA's (roughness average), the lower numbers are a smoother surface.

Some do lap the block, but I am very much against that because lapping may not create quite as flat a surface as milling. Not only must the surfaces be smooth, but they have to be very flat.

Another method:
IF you really wanted to use a MHG without having it machined, some people are using Permatex Brake Quiet and spraying that on to help aid in the sealing since this material will conform to very small surface irregularities.

Some do just go ahead and not go by the manufacturers' recommendations of having the block milled. Some of those have had luck--although it is not recommended that way. Although some had luck without milling, it is not the book as the proper way to set up for a MHG. You would be taking a chance not going by the proper recommendations.

[kewlcoconut]

im also in the process of replacing my HG. you mentioned "Permatex Brake Quiet", but I heard that a copper spray works good as well because it has high heat resistance. which would you recommend that works better?

[Strannik]

use copper spray
and i would use it not only on headgasket, but on other gaskets as well (like intake, exhaust etc...

[rnoswal]

Almost no head gaskets require any adhesives at all. They are not recommended. If you need clamping power then go with ARP studs. Metal gaskets are usually only for the turbo engines. A FelPro head gasket works just fine in an N/A.

If you do pull the engine, make sure you keep the front aluminum cover on the engine so it can be milled too.

As I said before inanother posting. Don't worry about buying an extra thick headgasket either if it is a N/A engine. The extra compression helps and the cams are easy to retime with the adjuster holes in the cam gears.

Russ

[TONY!]

Originally Posted by kewlcoconut

im also in the process of replacing my HG. you mentioned "Permatex Brake Quiet", but I heard that a copper spray works good as well because it has high heat resistance. which would you recommend that works better?

The Permatex Brake Quiet also has a high degree of heat resistance. Brake pads get really hot too.
The Permatex Brake Quiet is being used by some of the more experienced guys.
One of those guys put down like 900 HP at Vegas.
From the 4 guys that I know who have used it, they highly recommend it.

Originally Posted by rnoswal

Almost no head gaskets require any adhesives at all...

From the first statement statement, it implies that so some actually do recommend using a sealant. I was not aware that any manufacturers recommended a sealant at all. I know that Cometic does not.

Originally Posted by rnoswal

… They are not recommended…

What is recommended is that the head and the block be milled to a low RA. Some are not taking the block out, in that case, they are not following the manufacturer’s recommendations. If the block is not to be taken out, to get a low RA, then yes, Permatex Brake Quiet will be of great help. Some are even using it whom have had their blocks milled anyways.

Originally Posted by rnoswal

…If you need clamping power then go with ARP studs…

Clamping power is not the same as good sealing. Ideally, people should be going with ARP studs anyways, but clamping power will not fix surface irregularities. People do get BHG’s even with lots of clamping power.




All that said, use whatever you fancy.