Currently rebuilding my engine and I got the block decked and told the machinist I'd be using mls gaskets. I dont know if the surface is good enough though. I got the gaskets off of LCE. I also have a set of toyota head gaskets in case I should use those instead.

 

Ask the machinist what surface RA (Roughness Average) the block is finished to.

From LCE's website, the RA should be 15-30. Being in the 15 -20 range is probably the best.

 

Here's the page (I think) old87yota is referring to: https://www.lceperformance.com/MLS-H...-p/1024040.htm (yeah, I like to see the cite) Why LCE would specify RA in uInches instead of umm is beyond me.

But what does that actually mean? This chart gives some examples. https://www.cnccookbook.com/surface-...e-calculators/ 30 uIn RA is a very smooth milled surface. Your machinist may have a gauge like this: https://www.mscdirect.com/product/details/00355172 (compare with your fingernail). I'd be really surprised if an automotive machinist had a profileometer.

 

If you hold your fingernail 90 degrees to the surface of the block and drag it across can you feel the ridges? Does it feel like your nail “catches” it? Not terribly scientific, but not a bad way to check a machined surface before reassembly.

 

Have the shop pull the alignment sleeves out of the decked surfaces on the block. Take a drill press cast iron tool rest and spray it with adhesive and attach 320 grit 3M wet or dry Emery cloth to it and wet with WD-40. Move the tool rest in large sweeping figure eight motion across the deck and head surfaces. As you take off the machining mark's from the fly cutting you will see that the webs between the cylinders will not be cleaning up. That is because the surface machining tool pressure varies as a function of the machine tools rigidity, how fast the machine shop made the cuts and the surface area that is cut as the tool crosses the deck surface. Because the webs are slight in surface area the cutter takes an ever so slightly deeper cut as it crosses the webbed surfaces between the cylinders. Thus the deck is not flat and will be recessed slightly between the cylinders. Lap the decks of the block and the heads until the machining mark's go away. This took three applications of different grits at 320, 400 and 600 3M wet or dry Emery cloth to get my block and heads in order for the MLS gaskets. The heads process much faster with the aluminum. I used the LC engineering kit with Greenlee MLS head gaskets with ARP head studs.

 

Hey guys, thanks for all the replies and information but i decided to go with the toyota oem gasket. The surface wasnt to my liking. I did also put headers and ARP studs on though so hopefully that makes a difference.