Inliners International Forums General Discussion Engines MLS head gasket on regular block?

A couple years ago I built a new short block, 307 pistons, mild cam, etc. Block had a clean up pass but was not zero decked.
Just picked up a rebuilt head that had a very light cut to clean it up.
Neither of these had anything above and beyond standard machine shop work, ie nothing specific on the head gasket surface.

Can / should I run MLS head gasket? Now that one of our inline boosters has them available! I've heard they are much more resistant to failure which the 4 bolt head pattern and increased CR makes me a little leery of. If I did that I would use studs. Other option is reuse head bolts and run a conventional gasket (have McCord, Victor, Detroit, and Fel-pro hanging around the shed).

Input / opinion?

They do require a much finer surface finish on both the head and block or they will not seal as intended. And both the block and head have to be machined, its not an either/or option. This is also something that not all machine shops can perform that has older outdated equipment, so it may make you have to travel farther outside your area to find a shop that is qualified to do it. Adding to the cost of your budget also. But it is money well spent.

Oh, I was considering using their 0.027" gasket when I do a head swap, to decrease compression over the replacement 0.040" gasket. The head obviously will be decked down to 70cc or the smallest chamber I can get. So that surface should be fine. But my 42k mile bottom end I'm planning to keep as is, since it is low mileage and pretty tight. But it sounds like the factory deck finish might not be compatible with the MLS gasket? Maybe I need to stick with the rebuilder gasket until I rebuild the bottom end when I can afford the machine shop work and a decent set of pistons?

The finish that most machine shops put on the block and head is too rough for use with an MLS gasket because their equipment can't provide the finer surface finish that is required. So don't assume that because a shop can resurface your head and block that it will be ok. If they have to ask you what surface finish means, then they probably can't perform the task correctly.LOL

Well I was planning to just a head through Tom and have him do all the work. So I assume his heads will be MLS gasket friendly. But I was wondering about my factory deck finish on the block? Like I said, I'm postponing a bottom end rebuild for later on down the line. Focusing on swapping out the integrated top end and doing a cam swap.

I tried a MLS gasket without putting a mirror finish on the sealing surfaces and it failed. Make sure your machinist knows you plan to use a MLS gasket. And if you ever have to go back to a more conventional head gasket and you are running a lot of squeeze then you will probably have to re-cut the surfaces with a more aggressive surface finish. That is why I decided not to continue my R&D program with MLS - too much machining involved on my engines and prototype MLS gaskets were costing me $200 a piece.

You're correct Greg, that's one reason i've been so adamant about the minute details required to run this type of gasket. Unless the shop or person doing this is completely knowledgeable and experienced in the steps needed to perform the tasks precisely, it will fail as you have experienced. And I know you are a perfectionist and do everything top notch.

I thought MLS gaskets are reusable.
That is what attracted me to getting one, that and being able to run more boost without worrying too much about blowing a head gasket.

They are reuseable, just like a copper head gasket.

They ARE reusable - up to a point.
Depending on the type of coating on the composite layers it is possible to remove the gasket without disturbing the coating and reuse it. But my experience (on V8s) has been that after a couple of remove/installs the coating will delaminate and further use is risky.

So, just as you can reuse head bolts a couple of times before they start to take a permanent plastic set, you may also reuse the head gasket a couple of times, assuming all the laminations survive the previous head removal process.