How smooth for metal headgasket?

[v8s_are_slow]

I'm wondering how smooth of a surface I need to get the head and block for a metal headgasket. I mean what could I use to get it really smooth? My motor only has a few hundred (maybe around 1,000) miles on it. Had to take off the head (along with the Cometic headgasket) but wondering what I should do to clean off the residue to make it the nice mirror finish it was. I wanna make sure it holds tight. Wouldn't think it'd need to be decked would it???

Thanks!
Scott

 

[BrokenTsi]

Ive put MLS HG's on undecked heads/blocks with ARP's and copper spray. Properly done, its yet to fail on me. If your having the head resurfaced etc, id look to get 20RA or better if possible, but otherwise its not absolutely necessary. And the copper spray allows it to be a little more forgiving imo.

 

[v8s_are_slow]

I dunno, I read up on the copper spray and supposedly you shouldn't use it. I know it says NOT to use it on the package that my Cometic gasket came in. The expansion rate of the metal of aluminum and the block is different and the metals in the gasket can't move like they should thus making it bow up (best terminology I can think of at the moment) and possibly leak.

I wouldn't think it'd need to be decked other than just making it clean and smooth cause I know it should be pretty straight. I could be wrong though. What to use to make it smooth though? Wire wheel or something? What's 20RA?

 

[GVR4592]

Ideally it should be resurfaced again, just removing the cylinder head can cause it to warp. Ra is the specification for how smooth the surface of an object is. The surface the Cometic is sealing against needs 50 Ra or better.

 

[v8s_are_slow]

K what about the block then? And thanks for the info.

 

[GVR4592]

The block is your call, most people leave it alone. A scotch brite pad will usually take off any residue that's left on the block. Permatex also makes a spray on gasket remover that will dissolve a lot of residue's on the block.

 

[Spoolin98]

A scotchbrite pad can clean the block up real nice. Just need some time and a lot of elbow grease,

 

[v8s_are_slow]

Eh, if it needs to be resurfaced, I'll probably just go ahead and get the block done as well. I need to take the shortblock out and have it checked anyway cause somehow I dumped a ton of oil on my way back from the track about a month ago. Already have the head pulled. Thanks!