How do you install brass seat in B&S Carb?

Discussion in 'Mechanic and Repair' started by Rain Man av, Oct 17, 2007.

  1. Rain Man av

    Rain Man av LawnSite Member
    Posts: 133

    I have a Walbro carburetor off a single cylinder 12.5 HP Briggs and Stratton engine Mod 289707, Type 0179. Carb has the numbers 41 in raised lettering just above and to the left of where it says Walbro. Walbro and 41 are on the side of the carb which faces the engine block when mounted. It does not have an adjustable fast idle screw. The riding lawn mower is Poulan Pro/Weedeater with 38 inch cutting deck. I read information on how to remove the brass seat of the carb, which I have not yet done. The problem I am having is that it appears that the needle is not seating properly while sitting still and not running. This was a prexisting condition of the mower when I bought it. I took the carb off, cleaned it, and reinstalled. It sat for two days, no flooding. On this particular carb/intake set up, the breather intake tube is attached to a point before and just above the carb bowl and before the venturi. When the bowl floods, gas runs thru the breather tube, into the breather, and into the engine. <BR><BR>I can start and drive the RLM around and mow just fine, no problems while it is running, it is not running rich. However, after I park and turn it off, after a while, gas leaks slowly out of the breather intake tube. It acts like the needle is not seating properly, as gas will slowly drip/seep out of the breather tube connector. I disconnected the breather tube to prevent gas from entering the engine. It's not a quick flood, just a slow annoying type of seep. I thought debris might be the problem, that is why I cleaned it. When I turn the carb upside down, the bowl actually sits below level. e.g. the end of the bowl opposite the pivot point sits below level. There is no way to adjust the bowl to level. The float is plastic and I have checked it for leaks. I have even replaced the float with one from another carb that does not have this problem, and still, problem persists. I've purchased and installed a new needle, problem persists. At this time, I want to learn how to replace the brass seat. I read how to remove the brass seat via a different thread on this forum. How do I install the new brass seat?. And if I install a new brass seat, will this cure my problem? P.S. How come you guys don't have a smiley of a guy banging his head against a wall? It would be so appropriate to me. Thanks in advance for any information you may have to help me end my woes.
     
  2. leeker

    leeker LawnSite Member
    Posts: 51

    yes the needle and seat is your problem. i have a self tapping bolt that screws into the seat made by briggs. the seat is then pulled out of the carb. i then carefully press the new seat in with a brass driff.

    i am trying to remember, but i believe it is a 1/4" self tapping bolt that is about 4 inches long.

    you will want to cleaned the carb well after this to get all the brass filings out of the carb
     
  3. Rain Man av

    Rain Man av LawnSite Member
    Posts: 133

    Hey Leeker, Thanks for the reply. What is a brass drift? I think I know what you refer to, but I want to make sure. Also, when you press in the new seat, are you doing it by hand, are you using some kind of machine? Can I use a hammer with the brass drift to press/hammer in the new seat ? Should I apply some sort of lubricant on the seat before pressing it in ?
     
  4. leeker

    leeker LawnSite Member
    Posts: 51

    yes i just tap it in lightly with a hammer and brass Punch, along as you are careful i have never had a problem doing it this way.
     
  5. Rain Man av

    Rain Man av LawnSite Member
    Posts: 133

    I pulled out the old seat - that was so easy. Now that I have the old seat out, I see how only the top 1/3 is actually "touching" the carb. I assume when I press it in, I want to press against the top of the new inlet seat, and not the bottom. The bottom being the point where the needle closes off the gas supply. I went ahead and placed the old seat back into the carb. Installing the new seat looks like it is going to be a piece of cake. And here I thought it was some deep, dark and mysterious process. Turns out, it's easier than hitting your thumb with a hammer. Thanks for your help. I've been asking detailed questions so hopefully the next guy can find all the answers he/she needs in this thread.
     
  6. leeker

    leeker LawnSite Member
    Posts: 51

    yes, you are right. press on the top of the seat not inside of the seat. glad you got it !!!
     
  7. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Hey leeker,

    I made the below tool for installing these seats.

    This distributes the shock of each tap around the whole top edge of the seat. So, No worry with making sure a drift is held straight so not to tap on one side more than the other.


    [​IMG]
     
  8. Rain Man av

    Rain Man av LawnSite Member
    Posts: 133

    Very nice, well done image. Thanks for the info on how to install the new seat. I will build myself one of those jigs in your picture. again, thanks:drinkup:
     
  9. leeker

    leeker LawnSite Member
    Posts: 51

    hey restrorob,

    thanks for the input, that is a good idea you came up with. i have had success with the way i was doing it, but i am always up for a better and easier way. by the way i was very impressed with your picture

    thanks leeker
     
  10. SLR

    SLR LawnSite Gold Member
    Posts: 3,218

    Another restro-rescue-remover!Brilliant as usual!
     

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