After spending some time talking with Cometic about their new MLX gasket, I pulled the trigger and ordered one. I planned to put it on my Junker thinking it could solve my head gasket woes, but Cometic recommended I don't run an oring with the gasket, even a softer copper oring was a no-no, so I put it on the shelf. Luckily a few weeks later the head gasket blew on our other 1995 test mule. We didn't machine the block (it was within 002" but we wanted to test this as a viable option for guys not pulling the entire engine. If an engine is going to the machine shop, it's going to get fire rings or orings, but for the average customer with a blown head gasket, this might be a fix. We started with a fresh machined head and new ARP 2000 head studs torqued up to 125 ft lbs, drivin cautiously for a couple days, then warm re-torqued to 130 ft lbs. We gave the gasket a fair chance to hold power since the previous setup was the original 280k headgasket with simple re-torqued head bolts (old gasket blew first dyno run with compound turbos when torque surpassed 1200 ft lbs). The MLX gasket immediately spewed fluid the first hard pull on the dyno. We checked the studs and all were good and tight at 130 ft lbs, but we cranked them up to 135 ft lbs to really get some additional bite on the new MLX gasket. The next dyno pull, it mixed fluids and pushed lots of soot into the coolant.
We made a couple more dyno pulls to finish our numbers testing and then quit before we hurt the engine. Removed the head and fire had traveled between the layers of the MLX gasket, punched through the pinch weld that holds the layers together around each cylinder, and then allowed all kinds of mixing and problems between the gasket layers. There were no signs of leakage on the top or bottom of the gasket, no flame trails through the viton coating, so the gasket did flare out nicely and seal well to the head and block, it simply was too weak and allowed the fire and combustion to travel through and between the layers.
In short, new MLX Cometic Gasket is ABSOLUTE JUNK!!!!
We went back with an in-frame Isky Groovomatic 041" oring and aftermarket head gasket, did our usual retorques, using same head, same studs, same everything other than new gasket with orings, and the head gasket held up to several hundred more test sessions ranging from 1000 ft lbs to 1400 ft lbs. It held up to several abusive burnouts, track outings, employee parts runs, a couple sets of tires, etc. The in-frame block oring setup isn't reliable for big HP, but it held great on this truck in the 500 to 650HP range and proved to be much better than the new MLX trash gasket. Maybe the MLX will hold with perfectly flat micro polished bllock deck and cylinder head, but why waste money on the gasket when OEM gaskets with orings are so much better or firerings for big HP setups.