I would like to know of experiences with the new silicone head gaskets. Are they really an improvement over copper gaskets?
NO GOOD! Many reasons.
I bought one. It is like a modern gasket and they seem to work well. Most don't require any re-torqueing. However when I tried to use it I found that my oversize valves were too big and interfered with the gasket. The copper gasket cleared the valves just fine.
Herm: Can you expand on the "NO GOOD"
Check the other thread that tells and shows a pic of these gaskets.
They don't fit many blocks that have some rust pitting around the normal places.
Some don't line up with the water jacket very well, or not at all.
The fit, or coverage between the cylinders is to skimpy.
My opinion, they just don't have the sealing power of the copper gasket.
You can't seem to get by with just a little warpage either, with head, or block, like in a used motor.
Here is what the silicone gasket looks like.
Just tiny beads of silicone around the water jackets, but none between the cylinders. Pretty lame gasket for the needs of the Model T engine with its old and worn surfaces.
Silicone head gasket, the red lines are the silicone beading.
Gaskets on high compression heads or Ford heads can blow out at the cylinder area.
To have the best results, use a quality head gasket and coat it with a sealer, then torque the center head bolts first, to squish the gasket tight between the cylinders, where the gasket has the thinnest width.
I've got two new ones in the wrapper that I'll trade 2 for 1 new copper gasket. No matter how much I retorqued I got leakage around head bolt between cylinders 3 and 4. Engine was a fresh rebuild with resurfaced deck and head.
No Good. I had water leakage at the rear. Gasket disintegrated around steam holes and rusted.
Stick with the tried and true copper with copper gasket spray.
DANG, that thing is skinny between the cylinders! Is that an optical illusion or is it REALLY that skinny?!
To coin a phrase: "Don't Experiment; Just Buy The Ones That Tom Carnegie Makes."
His copper gaskets are the best, in my experience.
Dan says, "Just tiny beads of silicone around the water jackets, but none between the cylinders." That is where the silicone belongs, as a water seal. Silicone will not seal combustion pressure. That is what the metal "fire ring" around each combustion chamber is for. On Dan's gasket it appears that these metal edges have been removed leaving a very narrow gasket between the cylinders. This will not work! Look at the gasket in the third picture and the metal edges can be seen. They may have been removed on Dan's gasket due to interference with the oversize valves as I mentioned in my post above.
The silicone gasket is no different than a composition gasket except for the silicone beads around the water holes and should work fine on a small bore-small valve engine if the surfaces are smooth and clean. Exceptions may be as Herm said when there is excessive rust pitting around the water passages or as I said when the bore size and valve diameter is larger than the gasket opening.
Yes, the photo I posted did seem a misnomer. The silicone gasket is a steel composite, with red silicone bead running around some of the edges. Sorry my first picture taken off the internet of that silicone steel gasket was incorrect photo image.
As you posted, the steel crimped edges are around the combustion chamber of the silicone steel gasket.
Still, the copper clad gasket, which is a sandwich of copper sheet and with composition material inside is IMO a better gasket. You can coat the copper clad gasket with copper coat sealer, and it does a great job. And can be re-used if needed.
The silicone steel one cannot as the silicone bead will be compromised after install. And the instructions on the silicone steel gasket says to not use any sealer.
Have run copper clad gaskets always, and they are recommend for the high compression heads. Have run with and without sealer. But the sealer does help, in filling in micro grooves or pits in the head or block surfaces.
The top copper gasket in the photo was sealed with simple aluminum spray enamel, but you can see the detail of where that paint helped seal. The bottom one was run with no sealer, and combustion carbon can be seem, which would not have creeped into the gasket areas as much if a sealer was used.
Have no experience with the new silicone steel gaskets, but seems to me the narrow silicone bead is just not hardy enough.
Makers of the 'Z' high compression head do not recommend the silicone steel gasket to be used with their product.
What sealer are you guys using on the copper head gaskets?
Copper-Coat. It comes in a can with a dauber, and in a spray can.
Here is the spray can version.
I ones used the spray can, but now I can't buy a spray can anymore, because it is not allowed to send it to Holland by air.I don't know or Lang's or Snijders sells the [dauber can]
I prefer aluminum paint as a head gasket sealant. I use it just like the KW or Permatex copper stuff - spray it on the head gasket hanging from a wire, both sides of the gasket. Let the gasket become dry to the touch, then assemble. I buy the KW / Permatex Copper spray if I can't find aluminum paint.
Also, the white composition head gasket that comes in the full engine gasket sets has been my favorite one in terms of zero leakage. It does not seem to be available separately so I use the copper gasket if I am just buying single head gaskets.
An old timer (egads, this was a while ago, think I'm as old now as he was then) told me to soak the head gasket in water overnight before using it. Theory being the composite material would "squish" more easily into the surface irregularities.
What's the group's opinion?
I got similar advice, also from a "old timer", when I was a kid, and soaked my copper/composition type head gasket for my high school Model A overnight. Don't know if it helped or not, but I never had any trouble.
Other advice from "who-knows-who", to grease both sides of the head gasket (copper/composition) so that it is lubricated which would allow the gasket to "spread" easier as the head bolts are torqued down. That did seem to make sense to me at the time and that also seemed to work just fine.
More recently, upon advice from club members, sprayed both sides of gasket (same type gasket) with copper coat and install gasket when copper coat was "tacky". Worked fine.
Have also installed new head gaskets perfectly dry and had no problem.
I guess if I have come to any "conclusion" from my previous experiences with head gaskets is that if the gasket is of good quality, and you torque it down properly, and if you "re-torque" the head bolts a time or two after the engine has heated up and cooled a time or two, you probably won't have any problem.
Only head gasket problems I've ever had were with those that somebody else had installed,....FWIW,.....harold
I should have said one more thing I guess.
Because I've always had good luck with head gaskets that I've installed, I guess I see this new type silicone head gasket as somebody's "solution" to a problem that so far, I've never had!
"If it ain't broke,....don't fix it!"
My farther told me many years ago that soaking head gaskets was only done on used ones.
Knock on wood! The copper head gasket on Nelybell was a used one from another engine. I did use Copper-Coat on it but have used grease on one side and CC on the other in the past. I drive a good amount and so far so good. Most stock engines are in the 50 to 55 LBs compression range or lower and only turn about 1500 RPM tops. People back in the day I am sure didn't go buy a new head gasket every time they scraped carbon or did valves and probably used grease on both sides to boot.