atljar

Anyone used the copper spray with cometics and still have them leak?

SStrokerAce

Jared.... Only reason them puppies leak is due to the surface finish on the heads and block. I have the tool to measure that which makes it easier to check, if you don't have a smooth enough finish then those bastards leak.

Bret

rskrause

What Bret said. They are very unforgiving of improper surface prep, any MLS gasket is. Not only does the surface have to be smooth, it has to be flat.

Rich

atljar

Ive read a little on the Ra of the machine work, problem is i have no idea what mine is. As the two of you are telling me, and as i have read everywhere else, that seems to be the biggest deal when using cometic gaskets.

On ls1 tech it seems to be pretty common to spray them down with some copper and I didnt see anything not seal after that. I would assume the copper spray is enough to get into the microscopic finish and have them hold.

SStrokerAce

Yeah i've seen that on felpros too for high cylinder pressure setups.

The Ra on the heads and block has to be below 60. Only way to tell is with a profilometer.

Bret