Head Gaskets

moper said
If the block and heads were not surfaced properly to run the MLS that's why they leak. You can try heat cycling them a few times if you havent, but if they continue to leak the finish is too rough for them. I only use the 1008s because of the flattened fire ring.

Ya all the big block guys here run the cometic's and work fine.
As for surface it was all done for the mls cometic's and still leak.
Other small blocks have same trouble may just put in the fel pro like I had. But lots of work to do that. Heat cycling them has been done.
Less head bolts on small block also.