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Discussion Starter · #1 ·
I've had gasket failures in the past with 11:1 motors so I'm asking the forum what precautions they take on a 102mm build to prevent blowing pressure into the coolant system on a 13.5:1 motor. I was planning on running the stage 2 cam and that's going to make a lot of cylinder pressure. I've milled the surface on the head and bought new ARP head studs. Is anyone using copper coat spray on the Cometic gaskets? and how much more are you guys torquing the ARP head studs over stock recommendations?
Thanks,
 

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From The Stix 2 Da Brix
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Idk if comitec makes a 660 gasket or not but I've had good luck with them before. Now I'm running a SCE head gasket now again I'm a 700 guy but I'm at 778 and 13.25:1 with stroke and it's been fine even dragging back2back in 95 degrees with 90+ humidity And never over heated good luck bro.
 

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Cometic EST (HD) Head gasket with studs. I did spray mine with coper coat as well. The EST gasket has a dead soft ring that goes around the bore of the cylinder.

http://www.cometic.com/est.aspx
 

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Discussion Starter · #5 ·
Thanks for the replies, I hadn't noticed the EST cometic gaskets were different from the others...I'll bet I have the regular 102mm top end kit sitting on the bench.
03 is the EST gasket teflon coated and are you spraying the head and deck or gasket or both?
What are you torquing your ARP studs at motojeff?
thanks,
 

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Thanks for the replies, I hadn't noticed the EST cometic gaskets were different from the others...I'll bet I have the regular 102mm top end kit sitting on the bench.
03 is the EST gasket teflon coated and are you spraying the head and deck or gasket or both?
What are you torquing your ARP studs at motojeff?
thanks,
Yea the EST gaskets have a couple layers, and there is a round ring that is inbetween them. That way the gasket is slightly thicker around the bore. Then when you torque it down it really clamps down around the bore. They are coated with that black stuff. I dont know what it is exactly. I still sprayed both sides. I also sprayed the single layerd base gasket with it.
 

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Discussion Starter · #8 ·
With my 3/8 bolt conversion I torque my head to 40 FT LB. I also use the 102mm Cometic MLG with no issues ...
What is an MLG? I tried to google Cometic MLG and didn't come up with anything? thanks
 

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From The Stix 2 Da Brix
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I talked with my very reputable builder he said cometic all the way.
 

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You should not have problems with your commetic MLG. I think the EST is a standard on the larger bore gaskets. I suggest you use ARP tourque lube to insure proper tourque on bolts. Remember-- If you up your tourque on head bolts, espesialy a 102 bore, you can distort the cylinder bore and effect ring seating. This is assuming no tourque plate was used durring a rebore. Make sure your matting surfaces are dead flat. Good Luck.
 

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I think you guys mean "MLS" which is the multi-layer steel gaskets which come in most of the Cometic top end and full kits you buy over the counter.

I have used them with 11:1 100mm engines for years without issue. Currently running a Cometic MLS on my 105mm 12:1 without issue.

The EST gaskets are nice, but of course cost more. I haven't had any issues with pump gas compressions on Cometic MLS gaskets.
 

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Discussion Starter · #15 ·
Thanks for all the info, and Thumper, no I did not use plates on the final bore and hone for this piston but I generally use motor oil when torquing anything over 25flbs. On a side note, I've always ran the stage 2 cam because it has produced so much bottom end power for the woods but now I'm approaching the big 5-0 and I don't race this Raptor in the woods, I mostly trail ride it, drag race and kick around with boys half my age on 450s so I'm considering dropping in my stage 3 cam. If I continue to go with the stage 2 and Kenz 13.5:1 piston that will make a crap load of cylinder pressure hence the ARP stud kit and all the questions I've ask. Anyway, I'm bolting up the head with clay on the piston this week to check clearance still considering the stage 3. I've set up my springs at 55lbs seat 160lbs open at 0.400",which I believe will be fine for either cam. Thanks again everyone.
 
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