Best sealing valve cover gaskets

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Fel Pro cork for me. Cheap and affective.
I get the bottom of the valve cover nice and straight, and hospital clean. Get out my Gasgacinch, and glue the cork gasket to the valve cover. Then I set it on a flat bench with some weight on top, and let it dry. After they dry, put them on, and torque to spec.

Through my experience, the oil gets out between the gasket and the valve cover, not the gasket and cylinder head. Its also, usually at the bottom of the valve cover.
 
You should be able to set the valve cover on the head without the gasket and have it touching the head all the way around. Try that and look through the holes to make sure it is seated all the way and not hanging up somewhere. A normal cork gasket should work unless something is screwed up. Put a straight edge or ruler on the cover rail and make sure it isn't warped.
 
RustyRatRod said:
Well, by GOD you got SOMETHING wrong somewhere. At this point, I would literally get a magnifying glass out and look at those valve cover rails on the heads. I have seen a couple have cracks in them before.
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Well I'm thinking maybe the winged bolts aren't tight enough, so I went and got some 1/4" 20 nuts, going to install them first and torque them down, the wing nuts will go over that.
 
gzig5 said:
You should be able to set the valve cover on the head without the gasket and have it touching the head all the way around. Try that and look through the holes to make sure it is seated all the way and not hanging up somewhere. A normal cork gasket should work unless something is screwed up. Put a straight edge or ruler on the cover rail and make sure it isn't warped.
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I couldn't get the cork local had to run the Felpro black composite (hard as hell) crap...that and the wing nuts can't get it tight enough? Gonna snug up with 1/4" 20 nuts first.
 
Johnny Dart said:
Fel Pro cork for me. Cheap and affective.
I get the bottom of the valve cover nice and straight, and hospital clean. Get out my Gasgacinch, and glue the cork gasket to the valve cover. Then I set it on a flat bench with some weight on top, and let it dry. After they dry, put them on, and torque to spec.

Through my experience, the oil gets out between the gasket and the valve cover, not the gasket and cylinder head. Its also, usually at the bottom of the valve cover.
Click to expand...
Ahh sounds reasonable, yeah I glued these on, they have a ridge around the sealing surface...ever see that, I bet the cork is softer and will seal better. I'm gonna try a 1/4" 20 tomorrow and see if I can get it tighter than the T nuts
 
InRogue said:
Well I'm thinking maybe the winged bolts aren't tight enough, so I went and got some 1/4" 20 nuts, going to install them first and torque them down, the wing nuts will go over that.
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should only snug the bolts with a 1/4 inch ratchet.
1/4 inch ratchet is all I use on 1/4 inch nuts and bolts.
Sometimes I just use a nut driver.
 
gzig5 said:
You should be able to set the valve cover on the head without the gasket and have it touching the head all the way around. Try that and look through the holes to make sure it is seated all the way and not hanging up somewhere. A normal cork gasket should work unless something is screwed up. Put a straight edge or ruler on the cover rail and make sure it isn't warped.
Click to expand...
The factory steel unit deffently wasnt flat, I removed the drivers cover (aluminum) and just look at the oil on the head surface...I'm checking them now

Screenshot_20200525-090209_Gallery.jpg
 
Try the straight edge on the head surface too. Could be the casting is less flat than normal.

I have the engine out of my car and pulled the valve covers yesterday. Cast aluminum Mopar performance with cork FelPro gaskets. When I put them on last year, I used RTV to adhere the gaskets to the cover and lightly tightened the bolts and let it set. Next day I torqued them lightly, and repeated the following day until the gasket stopped compressing and the bolts held torque. Fast forward to yesterday, two bolts on each side were "loose" or just over finger tight, yet I had no leaks. Process and decent parts will bring success.
 
gzig5 said:
Try the straight edge on the head surface too. Could be the casting is less flat than normal.

I have the engine out of my car and pulled the valve covers yesterday. Cast aluminum Mopar performance with cork FelPro gaskets. When I put them on last year, I used RTV to adhere the gaskets to the cover and lightly tightened the bolts and let it set. Next day I torqued them lightly, and repeated the following day until the gasket stopped compressing and the bolts held torque. Fast forward to yesterday, two bolts on each side were "loose" or just over finger tight, yet I had no leaks. Process and decent parts will bring success.
Click to expand...
Well I just removed and reinstalled, I clearanced the #1 and #5 area a bit more seemed a little close also added nuts to the studs before the T nuts, maybe the studs were a tad too long? Time will tell, had to clean up the underside of the car of oil and now it's raining out...

Go figure
 
I hope you got your leaks contained! Just ran across this thread, and figured I'd let others know what I found. I installed my 340 back in '89 and always had valve cover leaks. I finally found the problem - there is/was a bulge on the lower center valve cover bolt hole boss! It was at least 1/16" tall. The engine is apart now, so I ground it down flat, and when I put a straight-edge to it, I found that the area to the left of that bolt hole was also taller than the rest of the rail! I ended up hand-filing it down. It was maybe 1/32" or less. And I found that on both heads! Attached is a pic...it's hard to see, but the bump is just 'above' the bolt hole and slightly off-center.

20200530_175653.jpg
 
Good post. If your suffering from constant leaks having a good straightedge and carefully inspecting the sealing surfaces is definitely a must. With cast heads who knows how straight yours may be, not to mention who knows the history of 50 year old parts and what may have hit, scratched banged into these things over that many years.
 
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