Carb Dust Seal, Which Direction

[truckfarmer49]

Which way is in and which way is out? I was thinking that the open side should face out, and the flat side in, so that the vacuum from inside the carb could pull the seal tight around the shaft.

 

[truckfarmer49]

 

[truckfarmer49]

(dust seal for the throttle shaft)

 

[wore out]

Seal lips face what you are trying to seal, which in this case is external air and dust, you have it figured out.

 

[truckfarmer49]

(quoted from post at 11:58:08 11/05/20) Seal lips face what you are trying to seal, which in this case is external air and dust, you have it figured out.

Thank you!

 

[Tall T]

After installing the rubber cup until it seated, I saw that there would be excessive space between the outside of that seal and the brass plug. I didn't want to punch the brass inward until it touched the rubber to keep the seal in place and square so I installed the felt seal that came in the YT lit [b:bb80401b2d]after[/b:bb80401b2d] the rubber which left only the perfect space for the brass plug to be pressed in flush with the outside of the boss but bearing slightly on the felt.

In the kit diagram it actually looks like what I did was supposed to be the intended game plan because as you can see part 22 (rubber) and 22A (felt) are shown together with no special side notes indicating otherwise. the sheet also shows Type B and C carb designs, but the A of 22A, the part # of the felt dust seal, does not refer to another carb design.

Without the felt backing the rubber seal would have been too free to reposition itself in the bore.

 

[wore out]

(quoted from post at 00:36:00 11/08/20)

NO worries about the rubber lip seal going anywhere, as engine manifold vacuum will hold it inward.

The felt seal is for the choke shaft.