Mopar Big Block Exhaust Manifold Gaskets with Heat Shields

Postby cv70chall » 19 Oct 2015 20:47

Anyone having issues with these? Just curious.
Seems like a good idea.
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby Adrian Worman » 19 Oct 2015 22:56

No, never seen em, what are they then?
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby cv70chall » 20 Oct 2015 20:37

They are exhaust manifold gaskets with attached heat shields.

Here:

s-l1600.jpg
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby Adrian Worman » 20 Oct 2015 23:35

Ah, I see.
I take it they are shaped for factory cast manifolds?
Does the shield go over the top of the manifold ?
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby dave-r » 21 Oct 2015 9:31

Ugly.
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby cv70chall » 21 Oct 2015 11:43

The gasket with the shield is the passenger side. (How convenient)
I had thought that the shield was catching the tabs on the vc gaskets as the cover was seated down and forcing them upward/ outward.
It's the only explanation I have.
Have either of you ever heard of a way to space the passenger side exhaust manifold away from the valve cover?
Does anyone make a wider passenger side gasket- or can I use multiple gaskets sealed together?
There has got to be a way to space that manifold as it is so damn close to the Valve cover.

Any thoughts?

Ever since I replaced that valley pan and solved the vacuum leak I didn't know I had- she purrs now-
I just have to stop the leaks!
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby dave-r » 21 Oct 2015 13:18

Why are you using a gasket with a shield? I haven't seen one before.
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby cv70chall » 21 Oct 2015 13:26

It was a decision we made when assembling the motor to try to offset the fact the fact that the factory HP manifold was so close to the valve cover.
I'm now at a crossroads of deciding whether to remove that gasket and replace with a regular style one.
Any way to space the HP manifold so it's further away from the valve cover on that side?
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby dave-r » 21 Oct 2015 15:18

I'm not sure what you mean by "too close" to the valve cover?

If the manifold is too close to the valve cover to fit correctly there is something wrong with it or the valve cover.

I wouldn't double up the gaskets. You will be asking for leaks.

The manifolds should be able to physically fit even without any gaskets.
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby dave-r » 21 Oct 2015 15:19

You not just over tightening the valve covers?
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby cv70chall » 21 Oct 2015 17:25

Nope. I'm certain of that.
There is no way to space the passenger side out even an 1/8"? Either way, I will need to remove the heat shield gasket and replace with a regular one.
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby dave-r » 22 Oct 2015 7:48

I don't understand why it would need spacing out at all. What is different to your engine than anyone elses?
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby fbernard » 22 Oct 2015 8:57

Sometimes the manifold (right-side I think) is so close that it cooks the valve cover gasket.

It happens especially if the manifold flange has been milled to remove pitting. You can see it on manifolds for sale on eBay from time to time, some have a suspiciously wide flat surface because the flange has been milled so much there is no "lip" anymore, the whole manifold is the flange.

Some have a very wide lip, I guess those have never been milled.
I've read a lot of forum posts where people say manifolds should be mounted without any gasket. I'm too lazy to check in the shop manual, but I find this strange.

I've seen [copper] spacers from time to time on eBay for that purpose, milled in the shape of a gasket.
Or you could use a header flange (.25" thick) for the same purpose.
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby cv70chall » 22 Oct 2015 11:35

Mine look to be "un-milled". Still just horrifically close to the VC.
Anyway, I removed the cover and found that- once again- the gasket had been "pushed" inward away from the valve cover in the middle area and near the front lower stud area.
I picked up a tube of Permatex Copper this time and snagged a set of rubber coated fiber gaskets.
After some light work at the wheel to get them to fit snuggly into the cover, I did a test fit onto the head with just the gasket- and found that- due to the angle of the head (normal) and closeness of the heat shield on the exhaust gasket, when you set the valve cover gasket down, it actually hits the center 3 springs and forces the gasket to deform- thus pushing it "upward and outward". You actually have to work it down onto the head, past the springs and heat shield and then it sits fine.
So, I applied permatex to the head rail and then gently fit the valve cover over it and onto the head. This time, the gasket "snapped" into place and it felt like a good solid mating.
Hand tightened the studs and let her sit over night. We shall see this evening when I crank her up and look for leaks.
If this fails, then my only option will be to partially remove the manifold on the right side and replace the gasket.
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby dave-r » 22 Oct 2015 12:02

I have heard Mopar didn't use gaskets on the manifolds from the factory.

I still don't see how the manifold could push the gasket in enough to cause a leak. The edge of the valve cover would stop it.

But if the gasket is catching the springs then that would do it for sure.
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Re: Mopar Big Block Exhaust Manifold Gaskets with Heat Shiel

Postby cv70chall » 22 Oct 2015 16:21

Yup, that seems to be the main culprit. Had to "metal tape" the heat shield to the manifold to keep it clear while seating everything.
Final torque down tonight- and maybe will be driving by tomorrow.
Fingers crossed.
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