Surface finish for Cast Iron block/Aluminum Heads

[Chatt69chgr]

I read in another post that you need of have at least a RA50 finish to use MLS gaskets (like Cometic's) or the head may be prone to leak.  My engine is being assembled now and I am starting to worry about this.  I already bought $200 worth of Cometic MLS head gaskets but I sure don't want leaks.  We bored the 440 30 over but there was chamfer on one cyl so to prevent gasket overhang, we bought a larger dia MLS gasket.  I think 4.41.  My engine is zero deck and I am using the 84 cc stealth heads.  I seriously doubt that my machine shop had the ability to achieve RA50.  Should back up and use the Permatorque gasket.  I used a 45 thousandths gasket to give myself a little insurance against piston rock and bought the push rods accordingly.  What are my options as far as maybe using a Permatorque head gasket are concerned---don't they only make them in 039 and 051 thicknesses?  And I have no idea what diameters are available.

[Challenger340]

Yes, Cometic MLS Gaskets, ask for a finer surface finish when using their products.
That said,
There is far more to good sealing than "just the Ra factor", which has more to do with actual "Bite" impregnation of the Gasket surface.

Take it from a Guy who spent literally Thousands of Dollars upgrading my Surfacing Machine, so as to be able to attain Ra's of 30-35 for my Customers, only to see my Competitors stuff, done on a 1957 Broach, sealing just fine with FAR LESS pretty finishes !

440's have 17 Headbolts.
I wouldn't sweat it !
If it is FLAT, and Torqued with Adequate Clampload, I highly doubt you'll see a leak.
If it does, add a Can of Bars Leak and call it good.

[Chatt69chgr]

Thanks Challenger340.  That was the kind of info I was looking for.  I appreciate your insights.   Being the world's worst worrywort, I'll look for something else to worry about.