Heat Shield Placement?

[RichB]

I had exhaust leaks on my 273 4bbl engine, so I removed the exhaust manifolds to sandblast, repaint them and replace the gaskets. I have the original heat shield on the drivers side. I'm ready to re-assemble. On which side of the gasket should the heat shield be placed? On the head, or on the manifold? I don't want to repeat the exhaust leak problem.

FYI. For anyone removing the drivers side exhaust manifold, the only way I could get it out was to disconnect the brake line from the master cylinder on the power booster.

 

[dibbons]

I thought the heat shields served as the gaskets? Of course, if they do/did I don't know what happens if you try to re-use them.

I remember the heat shields being used on both driver and passenger sides from the factory (1965 small blocks anyway).

Forgot about this previous thread that goes into more detail:
Heat Shield Used With or Without Exhaust Gasket?

 

[mvh]

I put them under the gaskets, as the soft surface of the gasket is intended to seal against flat metal, while the textured surface of the gasket is intended to seal against the manifold. I don't know about originally, but I was dubious about using the heat shield as a gasket by itself, after being flattened so many times. It would probably work with a good sealer like Hylomar AF. I think by 67 the heat shield was on the driver side only.

 

[RichB]

From what I'm gathering, the metal heat shield on the left side was also the gasket.
The right side was a similar metal gasket but without the heat shield extensions.
I think what I will do is use the heat shield on the left side with high temperature sealant and no other gasket and use a gasket on the right side.

The coating I used on the manifolds is Seymour high temperature paint. I baked them for two hours at 425 deg to cure the paint and they look terrific. I will post the paint info and a photo of the manifolds.

 

[Cuda Al]

67 only had the driver side, earlier (not sure what years) had a smaller one (without the wings) on the passenger side. I had an NOS heat shield on my recent build so I treated it as a gasket.


Alan

 

[MoparLeo]

Very few manufacturers used exhaust manifold gaskets in the old days. Back then the exhaust manifold and head were both cast iron with pretty much the same expansion and contraction rates when hot or cold. Gasket are only used where either the materials are of a dissimilar material ( aluminum/cast iron ) or different surface finish. If your heads are true and your exhaust manifolds are straight, you won't need a gasket . only thread sealer on the outside exhaust manifold studs/bolts.

 

[FJRdoc]

Agree with the above post. The only issue is that sometimes exhaust manifolds can warp over time. I had my manifolds surface to remove high or low areas before reassembly.

 

[dibbons]

Some of the Fel-pro sets have the exhaust manifold gaskets in three pieces (one center gasket and two outside gaskets). Once I had an outside gasket flipped upside down and ended up with a slight exhaust leak-they only fit properly one way.