Briggs Intake Manifold Gasket

[depawl52]

Greetings. I'm changing the carburetor on my 23 HP Briggs V Twin on my JD Zero Turn. The new carb comes with gaskets, which include gaskets for the intake manifold (see attached), which are different than what I found when I removed the carb (O Rings).
So, when installing the new carb, should I remove the existing O Rings (even if they appear to be in good shape), and install the new gaskets, or install the new gaskets over the existing O Rings, or just do nothing and reinstall the manifolds and leave the existing O Rings untouched?
Anyone know why the O Rings supplied with the carb are different than the original?
Thanks.

 

[ILENGINE]

If the existing O rings are in good shape then reinstall them. Don't remove and use the other gaskets or try to put the gaskets over the O rings. The plastic intake that is used with the O rings is not rigid enough to properly torque a normal gasket. And could create an air leak at the junction.

 

[depawl52]

Thanks ILEngine. That's kind of what I was thinking. Makes one wonder why they even include the gaskets with the carburetor.

 

[Forest#2]

I take little bit of extra care in this area especially if the engine has a surging and hunting issue. (and a dreaded Nikki carb)
I use the gasket over the o-rings, but I've also used the gasket W/O the o-rings. If I have no new flat gaskets available I make the manifold gaskets myself. I trust the gaskets with the Permatex more than I do using the old or even new o-rings.

I always use a light smear of permatex gasket maker on each side of the gasket when re-installing.

If you look at the plastic manifolds they have a steel collar insert through the mounting holes that limits the amount of plastic compression to the manifold seal and can result in leakage when re-using old o-rings. If too thick of a gasket is used it's possible that the plastic ear on the manifold might crack when installing.

 

[ILENGINE]

If you look at the plastic manifolds they have a steel collar insert through the mounting holes that limits the amount of plastic compression to the manifold seal and can result in leakage when re-using old o-rings. If too thick of a gasket is used it's possible that the plastic ear on the manifold might crack when installing.

I haven't seen any crack from people trying to use the paper gaskets, but I have seen them warped at the mounting flanges so bad that the O ring won't even make contact with the head mounting surface after somebody tried to use the paper gaskets, and the mounting ears compress into the paper.