Head to Cylinder Seal?

[Handyjay]

On my recent rebuild the shop told me to use Copper Coat on the mating surface between the head and the cylinder. Now that I have the engine apart again for a broken stud and cleaning up the remains of the Copper Coat I wonder how effective this is. What are others doing that have not fly cut and installed gasket seals? Thanks for any and all suggestions.

[totle]

Install dry. No gaskets or copper coat.

[CaptainCalf]

Originally Posted by totle

Install dry. No gaskets or copper coat.

+1, I don't think a gasket or copper coat would help any if a head decided to lift and shuffle around under high boost, but flame rings would

[Ken911]

either cut them for flame rings or some shops lap the cylinder to the head with lapping compound. Imagine Auto used to do that.

[Tom Oxner]

Where are the flame rings available? Thanks,

Tom

[sjf911]

Originally Posted by Tom Oxner

Where are the flame rings available? Thanks,

Tom

TurboKraft did mine and then recommended lapping.

[JFairman]

Do you use common valve grinding compoud to lap them? If not what do you use?

[sjf911]

Originally Posted by JFairman

Do you use common valve grinding compoud to lap them? If not what do you use?

Yes, valve lapping compound (fine) with the rings removed.

[JFairman]

Thanks, thats what I figured.
I'm guessing you put some on the surfaces and with light pressure rotate the head or cylinder back and forth by hand for a minute or two or until there is a nice uniform freshly lapped grey finish on the entire sealing surface where the head and cylinder meets.
Then wash it off of course.

[sjf911]

Originally Posted by JFairman

Thanks, thats what I figured.
I'm guessing you put some on the surfaces and with light pressure rotate the head or cylinder back and forth by hand for a minute or two or until there is a nice uniform freshly lapped grey finish on the entire sealing surface where the head and cylinder meets.
Then wash it off of course.

I think marking the surfaces with machinist's dye was recommended but I basically did exactly as you wrote.

[jwasbury]

This is exactly what I was told to do by a reputable Ducati shop when I was reassembling my 900cc Duc engine after head stud replacement. Ducati engines are similar to the Porsche in that they do not use any head gaskets.

Originally Posted by JFairman

Thanks, thats what I figured.
I'm guessing you put some on the surfaces and with light pressure rotate the head or cylinder back and forth by hand for a minute or two or until there is a nice uniform freshly lapped grey finish on the entire sealing surface where the head and cylinder meets.
Then wash it off of course.

[fredmeister]

I used a scotchbrite pad and rotated the cylinders on it until they cleaned up nicely then used the pad on the head surface with my finger in the sealing area.

This is not so aggressive to scratch the surface but does nice to clean it up.

[GJF]

Whether you have flame rings or not..... If.... you lift a head you will have the same results. A freshly machined set of mating surfaces lapped, will give you the best sealing. More surface mass area for sealing. If you run a gasket of some sort and lift a head the gasket can become damaged and ultimately top end tear down will be necessary for repair. There are ALOT of BIG HP guys running lapped cylinders without rings. Just saying....

[Tippy]

I used a scotchbrite pad and rotated the cylinders on it until they cleaned up nicely then used the pad on the head surface with my finger in the sealing area.



This is not so aggressive to scratch the surface but does nice to clean it up.

Exactly what I did too.

[Ken911]

Originally Posted by Tippy

Exactly what I did too.

me too then i lapped them in with valve grinding compound

[Kraftday]

Its important to have at least the 3 slugs on that side resurfaced and verified the same height. If the ni-resist rings and grooves are added, then resurfaced with machined precision, you shouldn't have to do any lapping.

Just tell your machinist these parts are going on the next Mars Rover so they have to be clean and tight!

This latest engine project had some divots and uneven surfaces.. which means you have to take off more material to get min clean up.

Here is some eye candy complements of PMS:

[fredmeister]

Originally Posted by Kraftday

Its important to have at least the 3 slugs on that side resurfaced and verified the same height. If the ni-resist rings and grooves are added, then resurfaced with machined precision, you shouldn't have to do any lapping.

Just tell your machinist these parts are going on the next Mars Rover so they have to be clean and tight!

This latest engine project had some divots and uneven surfaces.. which means you have to take off more material to get min clean up.

Here is some eye candy complements of PMS:

Can you show an example of a mild case that needs work (before its machined) to give us an idea of whats not acceptable and when clean up is going to be required?
It would be great to have a benchmark to know when one can skip this and save some time and money or when its needed for a successful build.

Not being in the biz and seen alot of damaged heads before its hard to make the call if you're a guy like me doing this himself.

Thanks for your experience,
Fred