Exhaust Manifold Heat Shield?

[SPF Required]

I am getting some advice that installing heat shields between the manifold and valve covers are a worth while investment as a part of my 440 engine rebuild. I am being told that installing these will greatly decrease the chance of the valve covers leaking over time due to the heat from the manifolds (which will run a bit hotter now with the EFI installed).

I am leaning towards a yes, but would love any input from all you folks. Do any of you guys have experience with this? and as a point of reference, this is ultimately a modified engine (hence the EFI reference above).

 

[Big_John]

There is a exhaust manifold gasket that has a flange that sticks out above the manifold. I believe it's used in an RV application. The PO of my 300 swore by them and my car has them.... BUT.... Like any exhaust manifold gaskets they also fail after a few years and mine did. One of my spring projects is to pull them off my car. The factory didn't use any and that's how mine will go back together.

So... Yea, the valve covers don't leak on my car, but the exhaust manifolds do. IMHO, it's easier to replace valve cover gaskets every few years.

 

[Davea Lux]

The valve cover gaskets usually leaked at the center line exhaust ports. Do not use cork gaskets, they will get hot enough under hard use conditions to burn the cork. The later style composite gaskets have a higher heat rating, but they will still crack and leak over time. Never used the heat shields on passenger cars and I doubt they would help that much since most of heat issues were caused by the close proximity, ie directly over, of the gasket to the hot exhaust ports.

Another choice is to put some 1/4" shims (or less depending on what thickness gasket you were going to run) under the bolts for the valve covers and run a thick bead of the Permatex black high heat sealant on the cover sealing surface. The black sealer will form the gasket and the shims keep the sealer from squishing out as the cover is tightened. Note that the black sealant is a mother to remove once it has set up.

Dave

 

[CBODY67]

A (now former) co-worker had a '78 Cordoba 400. He was a stickler for cleanliness. Hated valve cover oil seeps! He must have used a case of brake clean to get that motor cleaned after he got the car.

He bought new valve covers from Chrysler, painted them, and they all ended up seeping. When I was at the Dodge dealer one day, I asked my friend in parts to look for what the police cars had on them. He came up with some valve cover gaskets that were pure orange silicone! I got some for my friend. They ended up seeping too, so I got some for myself and forgot about his issues!

Seems like they were for a middle-'70s 440 police application? By observation, the rh manifold is closer to the valve cover gasket than the lh is.

CBODY67

 

[Davea Lux]

A (now former) co-worker had a '78 Cordoba 400. He was a stickler for cleanliness. Hated valve cover oil seeps! He must have used a case of brake clean to get that motor cleaned after he got the car.

He bought new valve covers from Chrysler, painted them, and they all ended up seeping. When I was at the Dodge dealer one day, I asked my friend in parts to look for what the police cars had on them. He came up with some valve cover gaskets that were pure orange silicone! I got some for my friend. They ended up seeping too, so I got some for myself and forgot about his issues!

Seems like they were for a middle-'70s 440 police application? By observation, the rh manifold is closer to the valve cover gasket than the lh is.

CBODY67

That was one "fix" for gasket burn out on sustained high speed pursuits on the '74 and later cruisers. Those red gaskets were resistant enough to heat that they did not usually burn out. Down side was that they did not bond to the head or the valve cover, so they always had some weeping. We applied a thin coat of aircraft rated sealer to both sides of the silicone gasket and then they usually did not leak. Pretty sure that those gaskets went obsolete many years ago.

Mancini racing sells a "Carbon X" gasket that is made out of re-formulated Graphite that seals really well for high performance uses. Spendy, about $35 per pair.

Dave

 

[CBODY67]

The "red" gaskets weren't inexpensive, either. I believe I used some high-temp silicone to aid in the sealing myself. I suspect there might have been some other things for the RV market, which Dodge was big into in the middle '70s, too, but those "motor home" heads had different exhaust flanges from the normal B/RB heads, circa 1972.

The "other solution" would be to wrap the manifolds in ThermoTech, or similar, as people have done with their headers.

CBODY67

 

[Davea Lux]

That was one "fix" for gasket burn out on sustained high speed pursuits on the '74 and later cruisers. Those red gaskets were resistant enough to heat that they did not usually burn out. Down side was that they did not bond to the head or the valve cover, so they always had some weeping. We applied a thin coat of aircraft rated sealer to both sides of the silicone gasket and then they usually did not leak. Pretty sure that those gaskets went obsolete many years ago.

Dave

I am getting some advice that installing heat shields between the manifold and valve covers are a worth while investment as a part of my 440 engine rebuild. I am being told that installing these will greatly decrease the chance of the valve covers leaking over time due to the heat from the manifolds (which will run a bit hotter now with the EFI installed).

I am leaning towards a yes, but would love any input from all you folks. Do any of you guys have experience with this? and as a point of reference, this is ultimately a modified engine (hence the EFI reference above).

View attachment 165929

How much hotter your manifolds will get depends a lot on what kind fuel to air ratio you decide to tune the engine for. If you leave it someplace close to the factory settings, you should not see a big change in the temps. The leaner you run it, the hotter it will get. Take care in the set up so you do not wind up burning a piston.

Dave

 

[live4theking]

There is a company I think in TN that makes valve cover gaskets that have thin metal boned in the middle, but I cannot remember their name. It is for reaching and they are supposed to be reusable.

 

[SPF Required]

Thank you for all the the input! If I am reading all these responses correctly, it sounds like the key to a solution is a better valve cover gasket and not to worry about the heat shield thing...

 

[CBODY67]

I was just in the Fel-Pro "Find My Parts" section of their online catalog. Doing the drop-down menu for Chrysler 440, then going down the list of build variations to the "U" Code motor and clicking on it, all of the gaskets which Fel-Pro has for that particular application are displayed.
Graphics of the items, too. Of course, they will fit other B/RB applications, as desired.

The particular valve cover gaskets are latex rubber coated fiber material. Supposed to resist the head better? Probably "resistance" from added mass to absorb the heat and dissipate it to the cylinder head without significantly degrading?

In other looking around at valve cover gaskets, I also ran across some which resisted vacuum from pan evacuation systems.

Have fun in the menus!
CBODY67

 

[Big_John]

These exhaust gaskets are what is on my car and have blown out.

 

[CBODY67]

These exhaust gaskets are what is on my car and have blown out.

Too much back pressure? Or a manifold retainer that got loose? Not endorsing the product, just advise that it is available, no more, no less.

CBODY6t7

 

[Big_John]

Too much back pressure? Or a manifold retainer that got loose? Not endorsing the product, just advise that it is available, no more, no less.

CBODY6t7

No to both issues.

The exhaust gaskets are just prone to failure and that's why the factory never used them.

Funny story... The PO of my car bought my A12 Roadrunner from me. Against my recommendation, he used those same exhaust gaskets. They lasted a month or two. I got to say "I told you so" to him.

 

[CBODY67]

I remember when exhaust headers were "big stuff" in the later '60s and into the '70s. A "blow'd out gasket" was somewhat common. Many "tricks" were tried to keep them from doing that. Nothing really worked. Then we found out about "the black ones", with wire mesh reinforcement and a higher-heat capable main gasket. End of problems, unless there was something else causing the failures. Haven't looked to see what the current "best thing" is in that respect.

Thanks for sharing your experiences, Big John.

CBODY67

 

[ayilar]

Mancini racing sells a "Carbon X" gasket that is made out of re-formulated Graphite that seals really well for high performance uses. Spendy, about $35 per pair.

Dave, is this the one you are referring to?

 

[68PK21 440.6bbl]

On my 1968 Fury's whether 318 or 440 I used the cork gaskets, check for bent over tightened bolt holes and flatten as necessary, clean all bolts, bolt holes & surfaces of oil, red Permatex sticky goo on gasket (both sides), 1 healthy dot of red Locktite on each bolt, torque to spec.

On my running 1977 PK41 when I did a tune up I think I checked/tightened the bolts with a 1/4 inch ratchet by hand feel (don't go overboard).

Sooooooo.....

I don't know wot'da'hell Y'all going on about these oil leaks. heh

 

[Davea Lux]

Dave, is this the one you are referring to?

View attachment 373946

That's it.

Dave

 

[ayilar]

Thank you for sharing your experiences. After reading of the many miles put by @cbarge on the Boab, and additional positive reviews from @Dana and @saforwardlook, I decided to get the Fel-Pro MS90425 exhaust manifold gasket set with heat shield. I bought it from O'Reilly, as it had one in stock locally. Here are a couple of photos that @71Polara383 sent to me after installation on Medina's freshly-repainted engine.