permatex copper spray vs mls head gasket
 

Hey guys, I've got this BP block, fresh honed cylinders, ARP main studs, and new mahle/clevite rings and bearings installed. I have one more piston to put in, but anyway, I'm wanting the engine together as soon as possible.

There are little dimples in the block around the water jackets. I have a stock felpro mls head gasket to put on it, and I was told by a (real) mechanic, and friend, to use copper spray on all my gaskets to seal any imperfectons, then I mentioned copper spray to another guy with 4 BP swaps and a few b6 swaps under his belt that I know of, and a lifetime of working on cars, and he advised against using copper spray with a mls gasket.

What do you guys recommend? Do you use copper spray? I just want the thing to seal. It's my first complete rebuild and third head gasket job, but the others were just normal head gaskets, I didn't know MLS gaskets existed until I found the one on this engine when I took it apart.

I don't use them with MLS gaskets. 4 heads I've put on with MLS now on various cars and never had a problem. Make sure you head is machined for an MLS gasket though.

No, no, no. Copper spray has never seemed like a good idea to me.

The head was shaved and had a 3 way valve job done, and new stem seals..

I cleaned the deck of the block with a scotch bright pad, and I was going to get a long sanding block and try running some 1500 grit sandpaper wetted with pbblaster over it to polish it up a little. You guys have experienced the pitts around the water jackets too right? Is that anything I should be concerned with? In my searches for information I've read it is common, but nobody says what they do about it.

To have a MLS seal properly, both the block and head surface need to be perfect.

I do not use copper spray on any head gasket.

You may want to pull the engine back apart and have the block milled.

You say the nead was decked, How was that done? What equipment was used?
Is the surface shiny? or Dull colored?


How a block is decked
https://www.miataturbo.net/engine-performance-56/how-deck-4-cylinder-engine-block-64577/

Surfacing a Head for a MLS Gasket
https://www.miataturbo.net/showthrea...818#post863818

Why NOT to have your head belt surfaced.
https://www.miataturbo.net/engine-performance-56/why-not-let-your-head-belt-surfaced-64394/

I don't mean to start any fueds here but several of us here in the Northwest have used permatex copper spray on the factory head gaskets for several years if you don't want to have the block decked each time. The block seems to distort around the head bolt area just a slight bit and if not decked well over time blow a head gasket, maybe soon or maybe not for a year, but seems to happen eventually as it did to me back in 07 after 500 miles with only 10 psi. I tried copper spray then and it has been on the car ever since with no issues. When Bob Bundy blew a head gasket several years ago running 18 psi, I mentioned it to him and that we used to run it on our race car corvettes in the old days and that I had used it on my 02 Miata after blowing a head gasket, and it was working fine so far. We used it on his back then and he hasn't blown anymore and has used it everytime he freshens a motor with no issues. A couple more people are doing it with no issues also.
I don't want to start a big deal here but just posting what has been done up in our area, and all these are boosted cars run hard on the track. I know most say not to use it, but don't really see why not as it was made for single layer steel head gaskets in the old days and has been working for several of us for several years on the miatas without having to deck the block about everytime. Thanks

jmann.... You are right, some use it and have great results, others use it and it about fails on the way out the shop.

This is a hot topic on many fourm boards.

It really will be up to the OP on what way he goes.

If the MLS gasket is already coated out the package, I will still say not to use it.

But if it is a dry/non coated MLS gasket, I do not see any harm in using it, as long as it is applied properly.
Such as the single layer gasket used back in the day on the SBC.

But I will say, I have a close friend that has and still dose use it, But this is on a USED OE MLS, that has been cleaned of all the sealent from the factory, and the HG is on its 4th torque that I am aware of.

Bogus Like I said, I am just posting my knowledge to the OP. As stated several of us are using it with none of us having an issue so far after several years, knock on wood :vash:, and continue to do so with the miata facory brand head gaskts in original condition, no coating removed and no retorques. I am not saying to do it one way or the other, just posting again our experience with using it and not surfacing the block and Bob's car is running a 2L stroker setup making around 370 whp..

The only gasket I ever had problems with was a non OEM MLS gasket might have been a felpro It was obviously of different construction than OE. I have done several both with and without Permatex and never had a problem ether way. Seems to me like it would help if the surfaces are not perfect.

Bob

The head is shiny, and has the rounded lines, not the cross hatch like a belt sander.

Honestly I don't know which way to go with this, I'm probably going to use the stuff anyway, there's lines around the fire ring like in the first link posted above, just not that bad where it goes all the way over to the bolt hole.

I put 1500 grit sandpaper on a (new) chopping block like you'd use in the kitchen, and used pb blaster to wet sand the deck, then used some degreaser and took all the slickness off the deck. Started to install the ARP head studs, and after I got the studs finger tight, I twisted them about another 1/8 turn to sink them into the block. I read in a couple books that will give a better torque reading and better clamping force.

anyway, after I got all the studs in I stood back and looked, and the 2 front (timing belt side) studs stick up at least 1/4" higher than the rest. I don't recall the old bolts being different sizes, and all the arp studs are the same size. I ran a tap down thru the holes again and came out clean, and I can't see anything in the holes with a flashlight...so is that normal?

Since the tap has a taper on the first few threads, you may not have reached the bottom threads in the bolt hole.

Arp head studs have a allen bit hole in the tip, use an allen key and see if that will level the front studs.

Also read the part on head bolt hole cleaning here....

https://www.miataturbo.net/engine-performance-56/how-final-wash-engine-block-64598/

You are on the right track for cleaning the gasket surfaces.

https://www.miataturbo.net/engine-performance-56/head-gasket-repair-how-clean-block-surface-w-pistons-installed-65074/

https://www.miataturbo.net/showthrea...665#post862665

^

Thanks for the links, I bolted the head on the other day, turns out, when you sit the head on the block the 2 front bolts/studs are stepped up in the head too, so it was normal I guess. Either way, its on there! Let's just hope for the best.

+1 for copper spray stuff when u dont resurface the block.