Cork versus Rubber Valve Gaskets

Mustang Jim · Dec 28, 2011

I've developed a leak on one of my valve covers, so I will be changing the gaskets soon.

I see that there's the traditional cork gaskets and more modern (I assume) rubber gaskets. What are the advantages of rubber gaskets? They cost a bit more than cork, so I'm assuming that they seal better. Before I go and order a set of rubber gaskets, I would like to know what everyone thinks.

Thanks,
Jim

WTFO · Dec 28, 2011

We use the Felpro rubber ones on my buddy's Falcon. It's a solid cam engine so we're in the valve covers pretty regular but it's also a show quality car so no leaks on the ground is key.

69Rcode_Mach1 · Dec 28, 2011

Yeah the cork work fine, but the rubber ones are great if you are going to be taking the covers off every now and again. I have rubber ones as well and never had a drop.

gdog87 · Dec 29, 2011

Rubber most deffinatley

2+2GT · Dec 29, 2011

Cork gaskets are more conformative. I use them on my 289HP, and they hold up just fine to repeated R&R. Of course, I have stamped steel valve covers. Here's the deal- If you have stamped steel covers, use cork, rubber ones just don't seal well on them. If you have cast aluminum, you can use the rubber ones.

Hack · Dec 29, 2011

Rubber gaskets last longer and seal better. Cork dries out, becomes hard over time, then cracks and crumbles. Rubber is also less likely to stick to parts and tear when you pull them apart multiple times. Rubber doesn't permanently deform like cork. Also rubber can be molded in complicated shapes - excellent 1 piece oil pan gaskets come to mind.

I've used both and rubber is by far superior to cork in my opinion. However you will spend more for good rubber gaskets compared to cork. The cheapest gasket sets typically have cork. If you are doing a cheap re-gasket and then selling the car you might use the cheap cork gaskets. They do work - they just aren't the best.

horseballz · Dec 29, 2011

I like these:
http://www.summitracing.com/parts/MOR-93060/
A little pricey, but can be R&Red repeatedly, seal well and the extra thickness provided by the steel core gives that little bit of extra clearance needed for most roller rocker arms with standard-ish valve covers.
HTH,
Gene

iskwezm · Dec 29, 2011

I bought the Moroso gaskets above ^^^^^^. Waste of my money.Leaked A LOT. I have cast aluminum Motorsport valve covers, dont know if that matters.I went back to cheap cork gaskets and no leaks.

2+2GT · Dec 29, 2011

I consistently get about 6 R&R from a set of cork gaskets. Use expensive ones, not cheap ones. Makes a big difference. I've never had them crumble.

95Vert383AOD · Dec 29, 2011

Not to hi-jack but....

Does anyone know why they don't make plastic gaskets with the raised rubber seals (Like on Mod motors) for older motors like 289/ 302/ 351?

Mustang Jim · Dec 29, 2011

After removing my valve covers to repaint them, I put on a new set of cork gaskets and, after 3 months, they developed leaks. Granted, I bought the set for $5 at Carlisle. But, I thought they would have lasted longer. My last set lasted over a decade without so much as a drop of oil from them.

I found a set of rubber Fel-Pro's for $15 at Mustangs Unlimited. I don't expect to have to take the covers off very often, but I think I'm going to give the rubber gaskets a try. I hate leaks!

Thanks,
Jim

Rick 91GT · Dec 30, 2011

I like the cork composite ones, Mr.Gasket makes a decent set and I alwasy permatex them to the valve cover so they stay in place and remove with out ripping...no leaks

rbohm · Dec 30, 2011

i tend to prefer the rubber gaskets over the cork, mostly because the cork gaskers have a tendency to crack and leak over time.

Mustang Jim · Dec 30, 2011

Just so I understand, rubber gaskets DO NOT require gasket cement. Is that correct? Also, if I am to use cork, gasket cement should be used only on the gasket side facing the valve cover?

Thanks,
Jim

Rick 91GT · Dec 31, 2011

Mustang Jim said:
Just so I understand, rubber gaskets DO NOT require gasket cement. Is that correct? Also, if I am to use cork, gasket cement should be used only on the gasket side facing the valve cover?

Thanks,
Jim

Correct, here is the cork/rubber composite gasket I use Mr.Gasket 5870, they are .172" thick

BuckeyeDemon · Dec 31, 2011

i've used Permatex High Tack Sealant (80062) to hold the rubber valve cover seal to the valve cover. the Fel Pro set i was using wanted to curl in between the studs.

rbohm · Dec 31, 2011

Mustang Jim said:
Just so I understand, rubber gaskets DO NOT require gasket cement. Is that correct? Also, if I am to use cork, gasket cement should be used only on the gasket side facing the valve cover?

Thanks,
Jim

correct, rubber gaskets do not require sealant, however it is good to glue them to the valve covers with something like 3M weatherstrip glue. a few dabs in strategic locations will do nicely. and with the cork gaskets, you dont need sealant either, but again they should be glued to the valve covers as well, again 3M weatherstrip glue does real nice here as well. remember that while there is a fair amount of oil that gets up to the top of the cylinder heads, by the time it gets to the valve cover gaskets there is little pressure, so as long as the gasket is properly installed, the valve covers properly tightened up, and the gaskets in decent shape, there should be no leaks. over tighten the valves covers, especially the steel covers, or damage the gasket, and you will have leaks.

EP429 · Jan 1, 2012

rbohm said:
it is good to glue them to the valve covers with something like 3M weatherstrip glue

Ive used this in the past and will never do so again. It is a chore to remove A dab or two might do okay, but don't get overzealous. I had a friend once who put a solid bead of this stuff around his valve covers, we had to use a crow bar to remove them

BuckeyeDemon · Jan 1, 2012

EP429 said:
Ive used this in the past and will never do so again. It is a chore to remove A dab or two might do okay, but don't get overzealous. I had a friend once who put a solid bead of this stuff around his valve covers, we had to use a crow bar to remove them

in the future, try the Permatex mentnioned in my post. it's high tack to help hold gaskets in place. it kind of dries like bubble gum stuck to a table. i only put it on the valve cover side to hold it in place. thinner will easily remove it.

Mustang Jim · Jan 1, 2012

Well, I ordered the rubber gaskets from mustangs unlimited and I should have them in a couple of days. I'll try the high tack sealant.

Happy New Year
Jim

Cork versus Rubber Valve Gaskets

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