Why is there an opening here?

[george culolias]

I'm putting back to stock an L71 so I never had this apart, as the car came with a four barrel. I have the correct 840 heads now and the right manifold but why is there this exposed hole? Am I missing a spacer or something? I put a pen in the hole to show what I'm talking about. It's the same on both heads
Thanks for any help!




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[george culolias]

One more question on the manifold?

I have a threaded opening behind the last carb that didn't come with any fitting. Anyone know what goes in here? A part number would be awesome!
Thanks




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[John H.]

Re: Why is there an opening here?

George -

Those are the exhaust crossover passages - what intake casting # do you have?

[Joe L.]

Re: Why is there an opening here?

George-----

The opening that you have pictured is part of the heat crossover system. It will be covered when you have the proper intake manifold gaskets installed.

[Joe L.]

Re: One more question on the manifold?

George-----

I don't think that orifice goes "through" to anywhere (i.e. it's a blind hole). I don't think that anything goes in that orifice.

[Phil P.]

Re: One more question on the manifold?

nothing in the first pic--- the second pic looks like a power brake fitting if you have power brakes otherwise a pipe plug

[george culolias]

So just the gasket sitting over the top is right?

It is the heat crossover hole in the head that is exposed. And yes the gasket does sit over it. But nothing seals it???? It doesn't matter? The manifold doesn't touch there. Seems kinda odd but you guys know...

[george culolias]

Thanks Phil. *NM*

[Joe L.]

Re: So just the gasket sitting over the top is rig

George-----

The gasket "seals" the hole, regardless of whether the manifold overlies that area. Does it work? Well, millions of Mark IV engines have been made that used this same system and configuration. I don't know of one that's had a problem with it.

[Steve Wallach]

Re: So just the gasket sitting over the top is rig

My 68 L71 has this same set up, Joe is correct, the proper gasket (and Orange paint) are all that cover that opening. The threaded hole is for a vaccuum fitting. The right one depends on the options and year of your car. Paragon has many different configurations shown in their catalog. The Assembly Manual for your car will show the proper configuration depending on your options and it will give the part number.

Good luck,

Steve

[Stephen L.]

Re: So just the gasket sitting over the top is rig

As stated above, the gasket covers the hole. The gasket that is available today doesn't follow the outline of the original gaskets. You can make the aftermarket gasket look like an original by t******* the gasket appropriately. Easy to do.....

The top gasket is an aftermarket (GREY)
The center gasket is a correctly trimmed gasket (GREY)
The bottom gasket was trimmed to the contour of the manifold and exposed the heat crossover holes. INCORRECT. (BLACK)


The 1967 SERVICE MANUAL Photo of the manifold gasket I used as my example to trim the gasket.


Correct outline gaskets in place on the heads of a 427


INCORRECT gaskets on heads exposing holes


Hope these help.
Steve

[george culolias]

Awesome! Now who knows about the paint?

Did the gasket get painted orange? How did they do this at the factory if the manifold had no paint on it? I can tape it off, just curious.
Thanks everyone for the wealth of knowledge.

[george culolias]

Was the pipe plug, a square, out or in?

Or some other type, like an allen. Thanks again you guys are awesome!

[Joe L.]

Re: One more question on the manifold?

George-----

The reason that I mentioned that this was a blind hole on this manifold is that it does not appear to have any threads in it. If it actually does have threads in it, then it's likely not a blind-tapped hole and then requires a plug or a vacuum fitting.

[Terry M.]

Re: Awesome! Now who knows about the paint?

If the intake was aluminum they covered it with a mask and sprayed orange all over everything. The mask sometimes was not positioned exactly right and some of the intake got a little bit of orange paint on one side or another. Other times the mask was properly positioned, and it stayed in place, and the orange got only on the gasket and not the intake.