This should be an easy one for anyone who has an unused one lying around:
I just need to know what is an approximate thickness for the inlet and exhaust side valve cover gaskets? Most of the major suppliers seem to be out of these gaskets at the moment and it’s easy enough for me to order some cork/ rubber blend gasket material from McMaster-Carr and make my own in the interim. For an XK120, but that shouldn’t matter as these gaskets were used through the mid-70s.
Thanks.
The factory ones are typical “thin” gaskets. But better ones are made by Cometic. They are quite thick–a gasket-aluminum-gasket sandwich. Either works so clearly the thickness isn’t critical. IMHO; hopefully others will chime in.
Payen gaskets, made of a gray cardboard material, are roughly .04” thick.
This is what I’m looking for – thanks. I’ll round your number up slightly to 0.06 which would be 1/16" and looks to be what is currently on the car too.
I would order Cometic gaskets either from Terry’s or directly from Cometic. Cork is a pretty terrible gasket material for that application, and you’ll soon have seepage.
Why is that? Because it doesn’t go all the way around and could shrink?
Transmissions snd parts of the engine seal up well with cork…
Cork is not dimensionally stable over time and exposure to petroleum products. It’s fundamentally porous as tree bark tends to be. Cork gaskets tend to need ‘nipping up’ from time to time to minimize the weeping, and the long XK cam cover has too few fasteners to provide a nice even pressure on such a squishy gasket material. There was a time that cork, or rubberized cork, or paper (aka wood) were the deal for certain engine gaskets when used with the best goo of the day, but that time was like 4 decades ago. The Cometic gasket uses a modern polymer over a stainless core to provide a conforming leak free seal (without any sealant!) that lasts for years (maybe indefinitely? My E type is about 10 years dry with Cometics). And they are reusable virtually indefinitely if reasonable care is exercised in their use, making them very economical over the long haul. Even if someone is a factory original spec, old school points loving Luddite, why would you not use modern gasket materials, because why would you not want a clean (mostly) leak free engine?
Hey !! I resemble that remark!
I think there might be a disadvantage in that the copper washers don’t get enough load and will leak a little. If that’s not the case I think cork may be pretty good (for being ancient) because it doesn’t need much pressure to seal. It‘d have to be thin cork though so the rear half circles can still seal. So roughly a cereal box cardboard thickness. I think I‘ll spend the money for the cometic next time, like the idea.
I just measured a spare I have with a digital micrometer. The blue paper ones I bought from SNG measure 0.033", so, about matchbook cover thickness.
Much better, IMO, and well worth the cost.
I used Cometics on Tweety, and they were far superior to the paper gaskets.
I bought a 36" X 36" sheet of rubber/ cork blend from McMaster-Carr at a very reasonable price. I then placed each cam cover on top of the gasket material, marked out their profile with a black marking pen, cut them out with scissors but leaving a generous overlap, then placed a bead of black sealant to the underside of each cam cover followed by placing the covers weighted on top of the gaskets overnight on a wood floor. The next day I trimmed the excess gasket material away from the cam cover edges, placed a small bead of sealant at the cylinder head/ cam cover interface and secured both in place by finger tightening each nut as best as I could followed by one full turn of the wrench on each nut.
Its been this way for a few months and I have yet to see any leakage of note. My car is one of those with the “studless” cam covers (no nuts around the cover up front) too. A thorough cleaning is key and it’s imperative to not overtighten the nuts. Also, I reused my old copper washers by annealing them with a propane torch.
Annealing has always worked for me (especially for the cam oil feed lines) and my paper gaskets are almost leak free (especially since I sometimes reuse them, they are a bit damp), only a bit of sealant at the back of the head. Seems like cork does work well!