Copper w/o-rings vs. Cometic HGs

Slysc

Registered User
I have an O-ringed block and I was running rubber coated copper HGs. They leaked and so the next step would be to cut receiver grooves in the heads. That's gonna cost me $150 plus a new set of copper HGs ($125).

If I were to switch to Cometic HGs, I would need to take out my o-rings and fill in the grooves. Has anyone sucessfully "filled in" their O-ring grooves in the block? If so, how so?

Which would be more robust? o-ringed block with rubber coated copper HGs and receiver grooves in the heads or Cometic gaskets with filled in o-ring grooves?

Also, are the cometics readily available or are they still in development for the SC? How much do they cost?
 
The cometic headgaskets come with a ring around each cylinder on the top and bottom layer of the headgasket, therefore, deleting the purpose and reason for running O-rings. We have cometics on our race car and they seal great. They are reusable and you dont have to scrape off headgasket material everytime you pull a head off.
 
Dan,

Chris Mendola had receiver grooves cut in his block and wanted to use the late model Ford MLS gaskets. The grooves were filled with JB Weld and sanded smooth. To my knowledge the MLS gaskets never leaked.

If it worked with them I'm sure it will work with the Cometics. If I were doing it, I would spray the block side of the gasket with Permatex copper and allow to get tacky before installing. If you don't have time to wait for the Cometics you can use the MLS gaskets.

David
 
Dan, Cut the head and you will get the seal you should get. cutting the block is only half. On a diesel truck motor both are cut for a good seal. under boost a big cunnins is at 35-40 lbs boost all day all the time. I have never seen one blow a gasket unless it was over heated. I have my block and if I ever blow a head gasket I will o-ring the head too. How much boost are you running. A 25% jackshaft pulley probably wont help either. :rolleyes:
 
Thanks for the info Dave. I'm still undecided about which to go with. I though Mendola parted out his engine. I know Jim Demmit runs o-rings with copper and receiver grooves and he seems pretty satisfied.

What's the latest as far as the avialability on the Cometics?

Tim, I'll probably run about 15 psi boost this year but I'd like it to hold together if I end up putting an AR on it and want to run 20 psi.
 
Are the MLS gaskets really necessary if running the o-ring block and heads?

What other factors come into play when using the o-ringed setup?

I have been planning on this when I rebuld my engne, but still need all the advice I can get...

BTW, I will be running a small to med shot of N20 (probably not over 100 HP shot).


thanks!
 
sizemoremk said:
Are the MLS gaskets really necessary if running the o-ring block and heads?

What other factors come into play when using the o-ringed setup?

I have been planning on this when I rebuld my engne, but still need all the advice I can get...

BTW, I will be running a small to med shot of N20 (probably not over 100 HP shot).


thanks!

You should be asking is it really necessary to oring the block and or heads or will MLS gaskets do the job.

Oringing is old school...MLS gaskets are new school. Some people still perfer oringing over MLS gaskets, because the gasket will usualy blow before bending a rod.

I'm using the late model F-150 4.2 MLS gaskets on my 3.8 and the 347 turbo motor has Cometic MLS gaskets. Both are super strong and IMO way better than oringing.

David
 
David Neibert said:
You should be asking is it really necessary to oring the block and or heads or will MLS gaskets do the job.

Oringing is old school...MLS gaskets are new school. Some people still perfer oringing over MLS gaskets, because the gasket will usualy blow before bending a rod.

I'm using the late model F-150 4.2 MLS gaskets on my 3.8 and the 347 turbo motor has Cometic MLS gaskets. Both are super strong and IMO way better than oringing.

David


So are you saying that you believe MLS gaskets will hold better than o-ringing?

Can I also deduce that I may not want too good of a seal, as I would rather replace a HG than a rod?

Thanks!
 
sizemoremk said:
So are you saying that you believe MLS gaskets will hold better than o-ringing?

Can I also deduce that I may not want too good of a seal, as I would rather replace a HG than a rod?

Thanks!

Yes, I think MLS gaskets will hold as good or better than than oringing.

The rod bending thing is on a v8 turbo motor with thick deck aftermarket heads, not an SC motor. On an SC motor, before bending forged rods, the heads will lift causing either the oringed gasket or an MLS gasket to leak.

MLS gaskets are just easier to use. Just deck the block and heads real smooth and bolt them on.

David
 
I personally dont agree with David.

I have always used various oring setups to great success. When done properly YOU WILL NOT have a problem.


One thing to keep in mind is that head gaskets are a SAFETY ITEM. They save your motor. WIth that in mind...

I have had great success with stainless steel oringed heads with felpro head gaskets.

I have also had great success with stainless steel oringing the block along with copper headgaskets.

I have also used copper orings in both applications.

I perfer the stock gasket/ ARP head studs/and Oringed heads
 
I personally dont agree with David.

Damon,

Please be more specific, because it sounds to me like we agree on everything except which style we perfer to use.

You like the idea of using the headgasket as a saftey valve, and I don't.

David
 
The way i see it is that headgaskets are being overrated. I dont see how you need O-ring with an M90. Even with an AR an Oring motor wouldnt really be necessary. Cometic has a ring around every cylinder on the top and bottom layer of the headgasket and thats what seals it. There are 7 second turbo cars running cometics like we run.

Pro Mod cars running 6.10's at 240mph are running cometic headgaskets and they are running somewhere along the lines of 150psi from a weiand 14-71. And the flow of these blower are alot more than an M90 or an AR.
 
David,

Actually I perfer to not have the safety factor!!!..It loses races

I'd bend a rod before blew a gasket.

The problem with fords 3.8 or 5.0 is the amount of head bolts and head lift. Regardless of the size of our blower or motor 17psi of pressure is 17psi. I have lifted many a head at that value on a small block ford. This is why I perfer to use Orings and why the Cometic gaskets will work great. EVen if the head lifts it will reseal.

As far as why not use the MLS or Cometics?

Without properly machining your block and heads they will not work properly. Not all machine shops get the correct surface smoothness even if you go that way.

Oringing the heads and a stock gasket....It doesnt get much easier then that. The Felpro replacements also have stainless steel rings.

Also torque to yeild bolts dont help at all

And as for the guys running real fast with cometics....Those motors get torn down often, use 1/2 inch studs, have beefier blocks and thicker head decks...All of which help NOT to blow a gasket. Im not saying an MLS is not a good thing....Its just not all that easy a fix.
 
DamonSlowpokeBaumann said:
David,

Actually I perfer to not have the safety factor!!!..It loses races

I'd bend a rod before blew a gasket.

The problem with fords 3.8 or 5.0 is the amount of head bolts and head lift. Regardless of the size of our blower or motor 17psi of pressure is 17psi. I have lifted many a head at that value on a small block ford. This is why I perfer to use Orings and why the Cometic gaskets will work great. EVen if the head lifts it will reseal.

As far as why not use the MLS or Cometics?

Without properly machining your block and heads they will not work properly. Not all machine shops get the correct surface smoothness even if you go that way.

Oringing the heads and a stock gasket....It doesnt get much easier then that. The Felpro replacements also have stainless steel rings.

Also torque to yeild bolts dont help at all

And as for the guys running real fast with cometics....Those motors get torn down often, use 1/2 inch studs, have beefier blocks and thicker head decks...All of which help NOT to blow a gasket. Im not saying an MLS is not a good thing....Its just not all that easy a fix.
Just because the boost gauge says 17psi doesnt mean that 17psi is going into each cylinder. The back cylinders will get most of the boost and the front cylinders dont get as much. You can fix this problem if there was some type of individual runner system made in our intake manifold.
 
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