Gen 1. 120ft-lbs on cylinder heads??

[maverickagm]

So I'm preparing to have my OEM composite head gaskets replaced with Cometic MLS gaskets on my 7500 mile 93. I've got all the gaskets, new cylinder head bolts, and new heater hoses.

When it comes to torque, the service manual says 30ft-lbs, then a quarter turn after that. The cometic manual says to follow the manufacturer's spec. I contected them to see if a different torque spec was needed since the gasket material was changing from composite to mls. They said to follow the factory spec. All over forums, the recommended torque sequence is 40-80-120-120.

Here's my problem. I having the work professionally done. Imagine going up to a career mechanic and saying "I know the instructions and service manual say this, but I want you to crank those mofos to 120 because the internet said so".

My question is, where did this revised torque spec come from?? Does anyone have a manual or service bulletin to cite?

P.S.: 120ft-lbs into an aluminum block scares me. I know the Gen 1 bolts are gigantic chonkers, but jebus cripes that's a lot.

 

[Viper Specialty]

The torque spec came from me.

You're welcome. LOL

Just tell the tech doing it that they are free to use the OEM torque spec, and then when it leaks they can do it over again and pay for another set of gaskets. The original spec will NOT work properly with a compressible embossed MLS gasket.

 

[maverickagm]

Cool cool cool. Thanks for the reply. To be clear, I'm not claiming the information is incorrect. It's just confusing.

Out of curiosity, and I hope you don't mind me asking these questions:

How many mls head gasket swaps have you done at this spec? Also, do you know if there was ever any problems removing the cylinder heads at a later time, after they had been torqued to 120?

 

[Old School]

The torque spec came from me.

Does the 120 apply to Gen3 also? OEM gaskets were MLS and factory spec was 90.

 

[Viper Specialty]

Cool cool cool. Thanks for the reply. To be clear, I'm not claiming the information is incorrect. It's just confusing.

Out of curiosity, and I hope you don't mind me asking these questions:

How many mls head gasket swaps have you done at this spec? Also, do you know if there was every and problems removing the cylinder heads at a later time, after they had been torqued to 120?

<Activate Salty>
I literally designed and paid for the production of those gaskets, they only exist because of me... and if it wasnt for Cometic sticking it in my @ss, you would have bought them from me... as they continue to sell them to everyone else. New owners are great people, as they dissolved the agreement I had with the previous owners and now sell *my* products built with *my* subsidized tooling to everyone under the sun.
</End Salty>

By now, I have sold, installed, or directed over 1000 installations since 2007 when these were developed.

There have been dozens of subsequent removals and reinstallations in many cases, be it from other failures, rebuilds, or botched installs. I am not sure why you are so hesitant, 120 on a 9/16 bolt with literal inches of engagement isn't even that tight. I run our studded 9/16 Gen4/5 blocks at more than that... on moly lube on a fine thread. Thats WAY higher of a clamp load.

 

[Viper Specialty]

Does the 120 apply to Gen3 also? OEM gaskets were MLS and factory spec was 90.

No. Gen2/3 and 4/5 are totally different fastener sizes.

 

[maverickagm]

Oh snap. I didn't know the history of these cometic gaskets. I really appreciate the insight.

 

[Viper Specialty]

Oh snap. I didn't know the history of these cometic gaskets. I really appreciate the insight.

The biggest thing that people need to understand is that Cometic is only a manufacturer. They make excellent parts, and they also make trash. Just because something is branded Cometic does not mean its not the garbage version of it.

While I have my issues with Cometic and all of the BS over the years, I still use them as a manufacturer. We have more versions of higher level gasketing than anyone else in this market, by leaps and bounds. We have unique materials, designs attributes, high power versions, conversion based gaskets... you name it. None of these things are generally available through competitors. Unfortunately, the G1 head gaskets, because they are a more standard design largely "one size fits all", they made it into pretty much everyones ordering books.