I'm thinking of doodling a custom gasket up in CAD and using some place like SendCutSend. They can do cork, but I'd like to do this one time.
Should I use copper, aluminum, steel, or a composite? Is there a right thickness or just thin enough to be deformable?
The application is just sealing air, no coolant running through.
I would use something really soft. Intake plenums aren't torqued down very tight. Metal gaskets need to be crushed to work and I wouldn't expect the 10ftlb on an intake bolt to be enough.
Copper, something like hylomar blue on either side?
spandak said:I would use something really soft. Intake plenums aren't torqued down very tight. Metal gaskets need to be crushed to work and I wouldn't expect the 10ftlb on an intake bolt to be enough.
Engines that had stamped sheetmetal intake gaskets from the factory tended to have intake torque specs in the 40ft-lb range.
It should be noted that these gaskets would not be "flat" but would have raised embossments around every port and passage, and it was still a good idea to use a product like Gasgacinch or Hylomar to seal them up.
The reason why modern (V) engines use low torque gaskets is that the intake manifold torqued down that tight turned into a splitting wedge against the block, and it warped the heck out of everything. The less iron you use in the block for less weight and faster warmup, the more you are concerned about ring seal and keeping bearing clearances tight so you can run thinner, lower pressure oil, the more this block warping is a problem.
For an inline engine, I've made intake gaskets out of Mountain Dew boxes 
You can still find rolls of gasket material at auto parts stores in the sealants aisle. Gaskets aren't all that hard to make, and in the old days, you didn't call up a parts store and buy a gasket, you sat down and made one from material.
I've had custom copper exhaust manifold gaskets made before. I contacted an established gasket manufacturer who was happy to sell me a few dozen made off my CAD file. They may not be so accommodating with onesy-twosey orders.
What problem are you trying to solve that makes a metal gasket better than one cut out of gasket paper or Pete's soda case cardboard? BTDT, too, with something like a Wheat Thins box and a little cherry Chapstick for gasket dressing. Worked just great.
To add to the above, you could easily whip up a CAD drawing and print it out on paper, then use that as a template to cut/punch one out of real gasket paper if you want something a little fancier.
I'd put the gasket material up against the intake manifold, then tap around all of the ports and the bolt holes with the ball end of a ball peen hammer. This either cuts the gasket, or makes it easy to transfer out to cut with a razor or whathaveyou.
I first saw it in Pat Ganahl's book about Ford engines, in a photo where they were making new timing cover gaskets for a 427 SOHC. I guess you couldn't just pop down to the parts store and buy them.
I was thinking of copper with sealant but I have not seen anyone do this for the intake.
The ones I've seen have the passages embossed like Pete described or a with a rubber material embedded.
In reply to DarkMonohue :
I'm looking at metal for reuse-ability. I don't plan on taking the intake off often, but just in case I decide to switch setups.
In reply to j_tso :
Understood. I'd just plain old gasket paper coated in Chapstick. That makes it peel off easier.
A metal gasket will want to be embossed to seal the ports. If you have money to burn having an embossed shim steel gasket made, by all means do, but in that case you don't need advice from the proles...
I've hand cut them from 2mm ptfe with copper spray and they worked well. I think copper wod be similar.
Even embossed metal gaskets are for one time use. Fro re-use, you'd need tp build something with o-ring grooves on both sides, and I bet you could buy a crate full of regular gaskets by the time you get one re-usable one built.
Streetwiseguy said:and I bet you could buy a crate full of regular gaskets by the time you get one re-usable one built.
Good call. Price out buying a dozen gaskets and one copper gasket?
In reply to Mr_Asa :
that's the way it's looking, 1 out of 1/16" copper is $50, same price as 4 out of cork.
This seems like a lot of effort to avoid having to possibly buy another gasket some time in the future.
As far as gasket material is concerned there are a bunch of factors to consider. Including but not limited to:
If you don't want to buy a gasket in the future, coat both sides with Vaseline. It will come off at least one side intact, and the gasket will be reusable.
DarkMonohue said:In reply to j_tso :
Understood. I'd just plain old gasket paper coated in Chapstick. That makes it peel off easier.
A metal gasket will want to be embossed to seal the ports. If you have money to burn having an embossed shim steel gasket made, by all means do, but in that case you don't need advice from the proles...
Thinking about this more, embossing should be relatively easy. 3D print a male and female stamp.
Pete. (l33t FS) said:The reason why modern (V) engines use low torque gaskets is that the intake manifold torqued down that tight turned into a splitting wedge against the block, and it warped the heck out of everything. The less iron you use in the block for less weight and faster warmup, the more you are concerned about ring seal and keeping bearing clearances tight so you can run thinner, lower pressure oil, the more this block warping is a problem.
Modern engines have plastic intake manifolds with rubber O-ring gaskets, don't they?
In reply to codrus (Forum Supporter) :
They do NOW, but I'm thinking of all of the Ford and GM V6s and V8s with aluminum intakes that used low torque plastic/rubber intake gaskets to limp older designs through the increasingly more stringent emissions requirements.
All those Chevy 4.3s and 5.0/5.7 engines limping 50s era designs through into OBD-II, all those Ford 4.2s, all those Buick V6s and especially those narrow angle Chevy 60 degree V6s. You know, all those engines with intake gasket fretting issues.
Note that the Ford Mod motors and Dodge Hemis have flat intake flanges, and the LSs are really laid over. Sure they used plastic manifolds, but not all of them.
Can we ask what the application is that makes a custom gasket necessary in the first place?
Nothing too special, it's for a 13B rotary.
Just like the pic below, but the center ports need to be taller. The tiny center strip tore when I cut a stock gasket I had lying around.
So more like this one?
https://www.racingbeat.com/RX7-1975-1985/Intake-Gaskets/16733.html
If you put an adhesive (Indian head shellac or similar) on the manifold side, and vaseline or Chapstick on the engine side, the gasket will likely stay on the manifold and come off the engine cleanly if and when you change manifolds. You would have to use a new gasket when you introduced a new manifold for the first time. After that, each manifold you reinstall now has a gasket pre-installed and ready to go.
You could also stick it to the engine side instead, but I like the idea of the gasket coming off the engine cleanly. Leaning over a fender and scraping gaskets off, should you need to, is not much fun.
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