Using a MLS head gasket and only decking the head. Only reply with first hand exp

[sbeck]

I want to hear from some people who have actually attempted only decking the head and not the block when installing an MLS head gasket. I come from mainly the LS1 world and no one decks there blocks unless doing a full build when going to MLS head gaskets.

Was head gasket leaking / lifting before doing it?

Brand of MLS head gasket?

Stock or built shortblock?

Did you have any leaking issues after install?

Amount of boost and turbo also please.

 

[WES_393]

Was head gasket leaking / lifting before doing it?

Yes. Car was purchased with blown head.

Brand of MLS head gasket?

Cometic MLS

Stock or built short block?

Built. Manley/Eagle combo.

Did you have any leaking issues after install?

Immediately. The engine was leak-down tested before startup. With the head resurfaced and torqued to 90 ft/lbs (ARP studs) on a "cleaned up" deck surface, the gasket couldn't hold more than 100psi of pressure between cylinders 2 & 3. We pulled the head, wrongfully blamed the machine shop who resurfaced the head again, checked for straightness, and even gave the head a finer surface finish. We cleaned the block some more (fine grit sandpaper on a block) and verified it was straight as an arrow. The gasket again leaked during testing. Less this time, but still leaked. Whether it was gasket problem or not I can't say for certain. But I wasn't about to blow another $100 on MLS. I went with a Mitsu composite and have pushed it to 25psi with a 16g and 17* peak timing on E85. I plan to make 500hp on a Holset this summer and I haven't thought twice about the head gasket.

Amount of boost and turbo also please.

None

If your looking for success stories, you won't find many. Some guys have had success by spending countless hours resurfacing the deck by hand. Others have even had the deck resurfaced and blown the MLS gasket due to improper surface finish. If you ask me, they are completely unnecessary in the first place. With studs and a composite gasket guys have made well over 400hp, some over 500hp, without trouble. If you truly get to a point where you need a stronger gasket (not just blowing them with a crap tune), rather than resurface the head/deck for MLS I would have them setup for metal O-rings.

 

[turboglenn]

It's not my car but a close friends I helped build the last few engines on.

His car is in the 750+ range for HP. and originally the head and block were surfaced for MLS gaskets and it held until a wrist pin area of a piston let lcracked causing a knock and power loss... we replaced the piston and rod, honed the block by hand in the car, and put it back tother and it held fine until the next piston let go at the wrist pin (same place exactly as first one)

After that failure we put a new block in, resurfaced them upon building the fresh engine and again went MLS and this time the trans let go... while the trans was out we pulled the headfor some other work and ended up replacing it with a surfaced new head. butleft the block alone and again put an MLS on and it held good for a while until he wanted to change rods... he got the aluminum rods and had theblock worked over for them, then put it together thinking the surfaces were fine but this time the MLS wasn't holding well at all... would be fine driving normal,, but under pressure it would leak between 1&2 and 2&3....

We pulled the head again, checked the surface and it was good for a composite gasket and so that's what went on and it's held since but he's kept power a tad lower (not using nitrouse since either) the car made 672 last dyno it's on the collowing

PTE6765 billet wheel

Head gaskets hav ebeen both mitsu and felpro MLS not sure what one was on when it leaked i'll jhave to ask

Blocks were OEM style 6 bolts with nothing more than bore and clean up work until the aluminum rod clearancing on the last build

BOost ranges from 27 to 35psi and uses H11 head studs on the composite gasket he now runs