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3.5 Briggs & Stratton runs w/o a carb�s welch plug

Posted by loger (My Page) on
Mon, Apr 18, 11 at 16:45

Is it common for a 3.5 Briggs & Stratton to run w/o a carb's welch plug? The plug that is missing will let you see 2-3 very small holes with daylight just inside the choke plate to carb area. It appears there was a plug in place at one time due to lack of paint and no grime. The engine seems to run ok even though you have the machined air metering holes behind where the plug once was. Since my small engine work (since 1970) I h/n seen a plug missing or replaced one. I feel I have seen the plugs in 2-cycle carb kits vs 4-cycles. Please share your experiences with welch plug missing or welch plugs period on old Briggs engines.

Engine's Specs: B&S 3.5, Model # 90702, Type 305801, Code 8733002

Thanks! loger

Follow-Up Postings:

RE: 3.5 Briggs & Stratton runs w/o a carb�s welch plug

  • Posted by baymee LehighValleyPA (My Page) on
    Thu, Apr 21, 11 at 5:13

Probably one of those holes comes off the idle circuit and maybe the engine doesn't need the other two for high speed. It's probably running lean.

RE: 3.5 Briggs & Stratton runs w/o a carb�s welch plug

loger: It would probably be smart to seal off this port. You can use tape to check effect on performance then use a silicone for better longer term sealing or purchase another welch plug .

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