block surface question

[91Supra313]

I have done a bit of searching on here and maybe I am just missing it, but I am trying to find out what rating the block surface needs to be for an HKS stopper MHG. I have heard that it needs to be prepped a special way to make it seal properly.

 

[hvyman]

Needs to be machined to 30ra or better.

 

[91Supra313]

Thanks so much! Mods feel free to delete this one.