MLS Head gasket .030 Over Okay for Stock Bore?

Blown331LX · Feb 16, 2008

Rebuilding my engine again, just switching to forged bottm end and ditching the stock 94 HyP pistons. I plan on upgrading to ARP head bolts and ARP intake bolts as well as the MLS (multi layed steel) head gaskets because I plan on boosting or spraying down the road. My problem is the smallest bore I can find the MLS gasket for 302 in is a 4.030 bore made by MR Gasket. Is there a problem using a .030 over gasket on a stock 4.0 bore? Is there a head gasket that would be better suited for my application that would be standard bore?

5spd GT · Feb 16, 2008

Many headgaskets are 4.100". They run just fine

Many MLS gaskets are on factory rides as well.

You have no worries...

Blown331LX · Feb 16, 2008

You want your headgasket bore as close to cylinder bore as possible. The .030 are for 30 over bore and .060 for 60 and so on. I have never fun a MLS gasket on a 5.0. I know that the modular 4.6 and 5.4 use the MLS style and seem to do okay even though the first gens were know for leaking oil from the back corner of the headgasket. Are they worth the added cost? Are also heard some people are re-using them, is this possible?

Fast63 · Feb 16, 2008

like said earlier, most head gaskets are 4.100 I highly doubt it makes any kind of difference if you have it exactly the size of the bore or bigger by that much. It will just make a small difference in compression, very negligable.

vristang · Feb 16, 2008

fabfordtech said:
You want your headgasket bore as close to cylinder bore as possible.

Ideally... yes.

For 99.99% of what is being built on this site... diameter of the gasket will make no difference...

Run the gasket, and enjoy the motor

jason

Rick 91GT · Feb 17, 2008

vristang said:
Ideally... yes.

For 99.99% of what is being built on this site... diameter of the gasket will make no difference...

Run the gasket, and enjoy the motor

jason

I completely agree with that statement.... I actually use the Fel-Pro 1133 MLS on any bore under 4.100"

Besure to retorque them after you get some heat into the motor, thsi will ensure a leak free expierence. You would be fine using the standard Fel-Pro 1011-1 gaskets, I've run a ton of power through them with no issues. If you get greedy any gasket will blow, the MLS just tends to do a little more damage

Yes you can drill out the rivots, clean all layers, coat them and re-use them in a pinch. I still prefer to just replace them.

Blown331LX · Feb 17, 2008

Rick 91GT said:
I completely agree with that statement.... I actually use the Fel-Pro 1133 MLS on any bore under 4.100"

Besure to retorque them after you get some heat into the motor, thsi will ensure a leak free expierence. You would be fine using the standard Fel-Pro 1011-1 gaskets, I've run a ton of power through them with no issues. If you get greedy any gasket will blow, the MLS just tends to do a little more damage

Yes you can drill out the rivots, clean all layers, coat them and re-use them in a pinch. I still prefer to just replace them.

What do you mean they do more damage? My car is going to be a street car not really building a drag motor. With this said should I just run the standard Fel-Pro 1011-1? And is this one just a regular graphite style?

BlownFiveLiter · Feb 17, 2008

MLS gaskets aren't very forgiving, so if something is amiss with the air/fuel and you would have normally just popped the gasket, you may end up with something like a hole in the piston instead. I can't really answer which you should choose because it's ultimately up to you. My personal take, I'd probably run the 1011-1 and hope that if I ever lost a gasket, that's all I lost. With the MLS, you're probably not going to lose the gasket first.

Rick 91GT · Feb 18, 2008

StangGT1995 said:
MLS gaskets aren't very forgiving, so if something is amiss with the air/fuel and you would have normally just popped the gasket, you may end up with something like a hole in the piston instead. I can't really answer which you should choose because it's ultimately up to you. My personal take, I'd probably run the 1011-1 and hope that if I ever lost a gasket, that's all I lost. With the MLS, you're probably not going to lose the gasket first.

Matt is correct they also require the heads and block to have a specific RA finish for proper sealing.

The 1011-1 is a composite gasket (Performance Series) with a stainless steel fire ring, the 8548PT2 is a graphite (OEM style replacement gasket).

TokyoJoe · Feb 18, 2008

I have a .30 overbore and I use a felpro 3311 mls gasket that is for 4" - 4.1" bore diameters without any problems. AFter seeing a standard gasket after a few months of nitrous I switched to MLS. Don't let these guys scare you, you can pop a piston just as easily on a regular gasket. Just keep a good tune and you won't have any problems.

And yes the surface RA is essential on the type of gasket you are using

giddyup306 · Feb 18, 2008

I personally would stay away from MLS gaskets. As mentioned they can be a lot less forgiving as a printoseal type gasket. Some guys that run high boost applications refer to them as "fuses".

But you CAN burn a MLS gasket. I replaced this one last weekend.

Rick 91GT · Feb 19, 2008

Nice Job Mike.... What happenend?

I typically only put a MLS style gasket on a high compression or high cylinder pressure set-up, otherwise the standard style gaskets work just fine, require a standard surface finish and are a lot cheaper.

millhouse · Feb 20, 2008

+1 on using the gasket as a fuse.

The 8548's (tin firing ring) have been proven to work well as have the 9333's (stainless).

giddyup306 · Feb 20, 2008

I just remembered something. MLS gaskets usually have a thinner compressed thickness. This can change quench and in some cases cause p/v issues.

Rick 91GT said:
Nice Job Mike.... What happenend?

Rick,

This isn't my doing. lol I replaced that for a customer. The guy got the engine REALLY hot!

Blown331LX · Feb 21, 2008

What are you guys refering to when you say surface RA? And I know a good tune is important. Any gasket made or piston available can fail for alot of reasons.

millhouse · Feb 21, 2008

fabfordtech said:
What are you guys refering to when you say surface RA? And I know a good tune is important. Any gasket made or piston available can fail for alot of reasons.

RA stands for roughness average….and that's exactly what we are referring to in this case. The Comteics require a much finer surface finish, most likely because they don’t have the deformation properties that softer gaskets do. When you don't have the heads and deck machined to the appropriate finish, you'll most likely have issues with coolant leaks.

MLS Head gasket .030 Over Okay for Stock Bore?

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