340 Valve cover gaskets.

[Chris Pauluk]

My cars 340 has Mopar Performance finned valve covers and they're leaking. 

I can see they are cork, is there a "go too" gasket that everyone prefers?

Thanks. 

[burdar]

The cylinder head isn't a machined surface. It's just "as cast". This can make sealing a cast valve cover difficult. The stock stamped steel covers bend and conform to any irregular surfaces. A cast cover doesn't. Also, the stock covers have a couple notches in them on the inside lip to clear the intake runners. It's common for a cast cover to hit the intake in these locations. Make sure you clearance the valve cover so there isn't any contact. You can double up on the gaskets to get some extra height to clear. I've had to use two gaskets AND clearance the valve cover lip. It can be a PITA. If the cover is touching the intake at all, it's not going to seal.

Finally, I personally have no issue with using a little rtv on the head surface. Just don't go overboard.

[69bcuda]

My cars 340 has Mopar Performance finned valve covers and they're leaking. 

I can see they are cork, is there a "go too" gasket that everyone prefers?

Thanks. 

Get a straight edge and check all the mating surfaces. At least you will know where the irregularities are. Also make sure the cover is not hanging up on your intake. It really should lie flat w/o a gasket.
Some heads are flawed from the factor like this 360 head was. Notice the grind marks at the bolt hole. It was still a high spot even though it sealed...................

[cudabob496]

remove high spots

clean real good both surfaces

turn valve cover upside down.
lay bead of RTV on cover
place gasket
lay bead of RTV on gasket or head seating surface
place valve cover on engine, and tighten down half way
let sit for 3 hrs
tighten down all the way
don't run engine for 24 hrs

this is the only method that has worked for me, as surfaces are not perfectly
flat on my covers.
I use the gaskets from Mancini

[Chris Pauluk]

remove high spots

clean real good both surfaces

turn valve cover upside down.
lay bead of RTV
place gasket
lay bead on RTV on gasket or head seating surface
place valve cover on engine, and tighten down half way
let sit for 3 hrs
tighten down all the way
don't run engine for 24 hrs

this is the only method that has worked for me, as surfaces are not perfectly
flat on my covers.
I use the gaskets from Mancina

Thanks

Sent from my SGH-M919 using Tapatalk

[cudabob496]

I corrected some typos on my previous post

sometimes I have to trim a little off the gaskets, to get them
to fit properly on my valve cover.

when initially putting gasket on upside-down cover, I put
bolts in holes to keep gasket aligned.