'57 Cadillac Eldorado Biarritz RH exhaust manifold

[raul.kolk]

I'm having a few questions about '57 RH exhaust manifold.

According to '57 and '64 MPL '57 shares its RH exhaust manifold with '58, which has generator on it's right in the engine bay. Although I'm unable to get a clear reading of the part number on installed manifold, it looks like any other that pops out in Google for "1469298". Are the studs on '57 just unused? Or does something actually mount there in '57?

There are listed exhaust manifold bolts (8.4433 SCREW, EXHAUST MANIFOLD; 7/16" - 14) and washers (8.4445 WASHER, FOR SCREW OR STUD; 13/32"). Converted to millimeters, it seems that washers inner diameter is less than bolts outer diameter. Does that mean that the manifolds are fastened with just bolts, no washers used? Seems uncommon to me but thought that I'd ask while I'm at it.

[David King (kz78hy)]

I've noticed in several MPL books that washers are not always noted.   It has been my experience that lock washers are needed on the exhaust manifold bolts as the thermal cycling will cause the bolts to loosen and drop out. 

These are special bolts as the flanged head is undersize for thread size.  I have these bolts available to the OE specification.  Here is the link to my webpage  http://www.keepemrunningautomotive.com/engine.html

David

[The Tassie Devil(le)]

The general rule is that Exhaust Manifolds are attached to the engine via a bolt with a built-in washer.

This allows the bolt to be torqued down, and then, as the engine goes through its heating and cooling cycles, the Exhaust Manifold is allowed to "slip and slide", under the solid washer headed bolts, whilst remaining tight to ensure no leakage.

In most Manifolds, there are two bolt holes that are "smaller" than the rest.   This is so that the Manifold is aligned at the smaller holes, and the larger holes allow for the expansion and contraction to take place, without cracking the manifold.

One has to remember that the Exhaust Manifolds suffer greater heat and heat up a lot faster than the metal they are attached to, and if they don't move, they WILL crack.

Using Lock washers could enable part of the end of a washer to get caught in the hole, thereby not allowing the movement.

Next time you look at a new car, or an unmolested engine, have a good look at the Exhaust Manifold bolts.   You will never see spring washers there.

Bruce.