Not really, no. Nothing the coolant system can't handle, and all the oil holes are drains back into the pan, so the filtering system will pick up anything large enough to be a problem.

Exactly, the MLS shouldn't really leave much on the surface. The non-MLS leaves crap specially if some sort of a sealer was used as well.

Agree on coolant, but the oil holes? That grit will get through the pickup and directly into the oil pump/relief valve before ever seeing a real filter, right? Isn't that an issue? Or are you counting on the grit to be heavy enough to not get picked up?

In the past, I used the grease trick on the oil holes too. Then I would use a shopvac to suck up the grease/grit and do the best I could with a Q-tip right after. Maybe this is overkill. I can sure be persuaded otherwise, because it was a bit of a pain.

I'm about to swap an MLS gasket because I'm getting the head rebuilt after damaging my intake valves with an overrev. I'm pretty sure BogusSVO meant for this write-up to apply to composite HGs. Anybody use it on an MLS with success?

what kind of surface roughness does 80 grit leave? here is a quote from felpro website regarding MLS gasket surface roughness.

"Fel-Pro® surface-finish recommends a finish of 60 to 100 Ra (roughness average) for cast iron cylinder heads and blocks, and 50 to 60 Ra for aluminum."

I have no idea how one would test this at home unless you buy a baller surface roughness tester for like $2k.

They do sell surface comparators but they are $60 still too expensive for me to do a block or head every couple years.
http://ecx.images-amazon.com/images/...L._SL1024_.jpg

You already had the aluminum head surfaced. Is the block surface in good shape? If it is, I would just hit with brake cleaner and use a razor + soft bristle brush for detail cleanup. The instructions here are for composite HG, not MLS.

yes my block is in good shape and planned on just cleaning it as you describe. I wasnt posting just for my interest and the thread doesnt specify whether its for mls or composite. I was hoping someone had an answer for the DIY guy to get the specified surface finish at home.

I tried looking at a few charts that roughly showed what grits might leave equivalent surface roughness but my best guess was about 100 grit for the high end of the felpro specs. but it was confusing and not very clear so I gave up.

I know this is probably a bit too technical and precise but I was hoping like I said I wss hoping someone might have been through this and could say "always use 100grit aluminum oxide" for reference for us all.