Which end of the needle valve seat should face the needle?

[erikpn]

No information in either the seloc or clymer manual. One face of the rubber needle valve seat for the carb has a molded ring and groove to the hole in the center of the seat. The other face is flat and featureless. Which face should the needle set into? If set into the grooved end, you can blow into the carb while its upside down. A little more pressure is needed to close the valve completely to shut off fuel. If set into the flat end, it's harder to blow into it even if the carb is right side up. help?

 

[jerryjerry05]

Re: Which end of the needle valve seat should face the needle?

There should be no resistance if it's installed correct.Find a site that has parts breakdowns and compare what you have.
There are lot's of sites with parts breakdowns. boats.net is one.J

 

[RRitt]

Re: Which end of the needle valve seat should face the needle?

typically the seat has a small ridge machined into the side that faces the needle. The ridge makes makes contact with rubber for seal and reduces cost of manufacturing by allowing both needle and seat to work without requiring absolute perfect machining.

 

[Frank Acampora]

Re: Which end of the needle valve seat should face the needle?

The plain face sits down into the brass fitting and the grooved face contacts the needle.

However: it will work either way. It is simply that the grooved face provides more flex for better sealing against the needle. I do have a three carb 90 where the grooved ridge was worn so I flipped them over and they have worked well for years. I did need to adjust the float height though.

 

[erikpn]

Re: Which end of the needle valve seat should face the needle?

I went with the flat face facing the needle and the grooved face down. I noticed a slight bevel on the grooved face and it matched with the seat on the carb. There were not only groove ring on the face but 2 grooves running from the ring to the hole in the center. I think this caused an imperfect seal, my carb bowl was leaking and I could still blow air into it when the carb was upside down if a blew hard. The flat face seals better.