Cometics and hylomar

[8AV8]

Should I take the rivets out and spray hylomar between layers to prevent seeping?

 

[1FASTV6]

I didn't.

 

[Grumpy]

I didn't.

x2

 

[SNOWBIRD]

I Sprayed All The Layers...very Messy,,i Would Not Do It Again,do A Search On Block And Head Surface Preperation For Cometics (smooth) And If You Have Some Tiny Coolent Leaks ,throw In A Couple Of ...gm Seal Tabs In The Cooling System.....i Used Copper Spray

 

[8AV8]

So just dust off both sides with copper spray or hylomar?

 

[V6RACER]

If the surfaces are done right you should put them on dry..

 

[Big_D]

I spread the layers and spray them with copper with the rivets in tact.

 

[8AV8]

If the surfaces are done right you should put them on dry..

Cometic says 50 or smoother...have you ever used them with a little rougher finish. Maybe 60-70?

SCEs came off and they don't require as slick of a finish as Cometics.

I'm just trying to stay away from the machine shop.

 

[V6RACER]

I'd say get the smoothest finish you can... Find someone with a high speed surfacing machine for heads. Copper gaskets work better with higher RA as the copper is maleable..

 

[8AV8]

These were machined to 60RA. How much difference is that (other than the obvious....10RA:biggrin: )

Ever used Cometics on a 60RA surface?

I don't really mind getting the heads resurfaced, I just hate to disassemble the shortblock.
No metal in the oil and great oil pressure after a rebuild.

 

[blown okie]

I'm just trying to stay away from the machine shop.[/QUOTE]

yeah thats a good plan, i would hate having a flat true head.

 

[BEATAV8]

yeah thats a good plan, i would hate having a flat true head.

Meh... mine are flat and true. Still leaked coolant. Damn good gasket once you get past that little problem though.

 

[gnxtc2]

I drilled out the rivets and coated each layer with copper.

IMHO: I think the viton layer that Cometic applies is alittle on the thin side. If you every noticed an import multi-layer gasket, the coatings are much thicker. The new Fel-Pro multi-layer has a sticky surface and you can't open the gasket wrapping until ready to install.

and yes, I cleaned the head stud threads prior to appling moly lube. And they're not Mickey Mouse pistons either:tongue:

Billy T.
gnxtc2@aol.com

 

[1FASTV6]

Nice stuff Billy!

 

[8AV8]

I'm just trying to stay away from the machine shop.

yeah thats a good plan, i would hate having a flat true head.[/QUOTE]


I never said the heads weren't true. I was asking if how much difference there is in a 50RA surface and a 60RA surface....as far as it pertains to a cometic HG sealing up.
This is a fresh rebuild with SCEs that were seeping water into the intake. BTW a machinist has looked at the heads and block , like I said I hate to disassemble the shortblock as good as everything looks in there.

So...do you know if a 60RA finish seal cometics?

I feel like it will be fine but I was looking for someone who might have done this with success...

 

[Alky V6]

If you plan to use the Cometics, use the finish they recommend. You're not going to find an engine builder worth a darn admitting that he used the wrong finish on an engine build. If you must, use the rougher finish, then you can report to us if it worked or not.

By the way, nice Billy T. I didn't forget about the pump pic. I'm doing a pump today, so I'll have a chance to take that pic.

 

[blown okie]

I drilled out the rivets and coated each layer with copper.

IMHO: I think the viton layer that Cometic applies is alittle on the thin side. If you every noticed an import multi-layer gasket, the coatings are much thicker. The new Fel-Pro multi-layer has a sticky surface and you can't open the gasket wrapping until ready to install.

and yes, I cleaned the head stud threads prior to appling moly lube. And they're not Mickey Mouse pistons either:tongue:

Billy T.
gnxtc2@aol.com

i don't think there's anything mickey mouse about that motor( funny the dishes do kinda look like mickey) that looks sweet!!

 

[8AV8]

If you plan to use the Cometics, use the finish they recommend. You're not going to find an engine builder worth a darn admitting that he used the wrong finish on an engine build. If you must, use the rougher finish, then you can report to us if it worked or not.

By the way, nice Billy T. I didn't forget about the pump pic. I'm doing a pump today, so I'll have a chance to take that pic.

Thats what I'm gonna do. I hope time lets me get them on this weekend. If so ,I'll be able to make it to the track next weekend and I'll post results.

 

[vacuum 6]

I've had ok luck with my cometics. When the car sits for 2 weeks+ they'll weep on me. It seems more so since the weather is getting colder.

 

[gnxtc2]

Thanks all.......

From what I have gathered, in order to install Cometics, the machine shop should have a CBN or grinder type milling machine. In my case, I had to use a grinder type milling machine on the block because the shavings from the iron sleeves will stick to the cutter and gouge the aluminum deck. Also with the grinder, there is oil coolant flowing while milling and washes away the shavings. You could use either milling machine on the heads.

If the machine shop has a broach type milling macchine, just take your stuff elsewhere and not take a chance.

If you can take your nail and run it across the surfaces and if you feel anything, the surface is too rough.

Billy T.
gnxtc2@aol.com