Manifold crack? What you think?

[Gsw234]

So I'm replacing my carb with the one that Jim rebuilt for me. I took off the carb insulator and saw this. Is this a normal casting mark, or do you think it's a crack?

Also, I forget what the deal with gaskets on the insulator. Am I remembering correctly that they are not necessary?

Thanks gurus!

 

[NeverGiveUpYota]

Weirdest type of crack I’ve ever seen! IF it is. Only way to know is to pull the mania and see if there’s a ton of built up carbon on the underside. Mine was a thin line from front to back.
Regarding the gaskets, they aren’t necessary unless your insulator surface has a bunch of imperfections.

 

[Spike Strip]

I don't see a crack, I see casting marks, but difficult with these pix.

No gaskets if your insulator gaskets are intact. Give them a thin smear of Sil Glyde to keep them from sticking, next time.

 

[Gsw234]

Thanks! It doesn't look like a crack to me.. But some of the ones I've seen are tiny! I really don't want to pull the manifold as I've heard that can cause more headache if it's not leaking already. Any other way to know for sure?

 

[Spike Strip]

There's no crack that I can see. Even a hairline one you can see... Nothing under the PCV tube?

 

[NeverGiveUpYota]

Those pics are way better. I say it’s a casting mark too.

 

[HemiAlex]

Either a casting flaw or something tightened up too much into it.

A crack won’t run into itself like that in a stationary application.

 

[Gsw234]

There's no crack that I can see. Even a hairline one you can see... Nothing under the PCV tube?

I didn't take the tube out yet. I guess I should?
Thanks!

 

[Spike Strip]

Just use a mirror to look. That gasket is $20

 

[Spike Strip]

Cracks will usually be in this direction, following the rubs underneath....

 

[Gsw234]

Cracks will usually be in this direction, following the rubs underneath....


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Thank you! So helpful!

 

[Thornton Melon]

Cracks will usually be in this direction, following the rubs underneath....




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I recognize that crack anywhere.
Made the truck idle at a very quiet 1500 rpms.