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B&S carburetors


Dudley

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I'm glad to have read about several fixes for that disk that falls out of the carburetor tube. I had used a cap off a prescription bottle with baling wire.

My engine starts and runs for a while, then will die. Fuel gets to the carb thru the fuel line. A little gas in the throat gets it to start for a few seconds. Does this sound like needle valve seat problems or what? The engine is a B&S model 7704111, 13 HP from a 1977 Simplicity Baron. Can I buy a rebuild kit, and where?

Thanks
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Hi Dudley,
That 7704111 might be the S/N, but it's NOT the model.
The original Briggs is likely a 302431, type 0155-01.
The problem very well could be the needle and seat, which would call for a carb overhaul with the parts cleaned in a suitable carb cleaner to remove varnish and such.
Follow the procedure in Briggs repair manual 270962. That, and a carb kit, are available from any Briggs dealer or distributor.
Fred
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Have you checked the fuel inlet fitting for dirt and debris behind it? I have seen them collect filth in there and starve the float bowl when RPM's are increased.
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Right you are, Fred.

Now, about the numbers for the carburetor...they're on the flywheel cover behind the air cleaner? I pulled this thing apart once to replace the magneto, and had a heck of a time even finding the engine model number. In fact, I took the cover to the dealer so he could try to find it...which he did, of course. Maybe I'm just blind! I'll check it out when I get home tonight.

BUT...what do you suppose that disk is for? Just to plug the tube? Then why didn't they make it closed instead of open? So I could run the tractor after it fell out and let it suck in all the dust as I rototill, then have the engine rebuilt??? I had sort of assumed that that opening couldn't be sealed air tight, but obviously that ain't the case.

By the way, how much do you think it ought to cost to have this kind of engine rebuilt?
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Fred, the model number was stamped on the flywheel cover. The B&S page lists this as a 1977 30 CID horizontal shaft engine with a Flo-jet carburetor. Is the number you listed a Simplicity number, or a number I could use to ask a B&S repair place for akit?

Brian, I could be wrong, but I don't think this carb has a float. Do you suppose it does? because I also have a little problem with the fuel slowly leaking out, and maybe it's because the float is stuck.
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Dudley,
The numbers I gave were all B&S, but not BS! ;<) (They came from the "Engine Reference" under "Parts" on the Main Page here.) As I said, that sounds like the third, the serial number. You need at least the "Model" and "Type", and sometimes the "Serial Number", to get the right parts.
And that definitely IS a float carb. That's what a "Flo-Jet" is. That engine would only be equipped with the "large Flo-Jet".
Please don't attempt disassembly without benefit of the Briggs manual I mentioned. The emulsion tube MUST be removed before attempting to separate the throttle body and bowl body.
Fred
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Fred is correct, if you do not remove emul. tube before separating carb. halves you will ruin emul. tube AND possibly carb. body.Also there are a series of #S stamped in the blower housing usually behind air cleaner assy. Those #'S will give you the proper carb. rebuild kit as there are about 3 different kits for that eng. In most cases the emul.tube should be pre-soaked with a good penetrating oil prior to removal as they can be a bear sometimes to get out. Good Luck with your project! dlc
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Dudley,
Sorry to be unclear. The numbers referred to are the ENGINE, not carb, numbers. They are used to get one to the correct parts list to determine the carb parts.
Yes, the Welch plug is just used to close the hole. It is necessary due to die casting requirements. It is a fairly common problem to have it fall out after long use. Apparently Briggs did not design quite enough 'meat' into the casting around the plug, and the aluminum fatigues allowing the plug to loosen, vibrate, and fall out. The replacement plug must be installed "by the book"; which means with a full-diameter FLAT tool of sufficient mass not to 'bounce' when hammered to flatten the plug. The plug MUST end up FLAT when installed; neither convex nor concave. It is also common practice to use a high-strength epoxy to seal in the plug at installation.
The cost of a rebuild will vary greatly depending on condition of major components and required machine work. Sorry, just not enough information to speculate.
Fred
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Guys, thanks for all the advice and information. I went out and bought the B&S manual and ordered a carburetor kit today, and I'm sure I'll have this puppy running great again in no time.

(Famous last words)
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Dudley, If the metal plug won't stay in get a rubber freeze plug the right size to fit in there and tight it up and you never have to worry about it falling out again. Tim
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Thanks, Tim. I had seen the discussion on the plugs falling out and planned on doing that. Is a hardware store the right place to get such a plug?

Dudley
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Dudley, A hardware store would be as good as any place else if they have them. If not try an auto parts store. Or you can do like I did and make one out of two washers and a rubber shock absorber bushing. Tim
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I put in the kit and the tractor runs great. Thanks for all the advice.

The kit had a replacement welch plug, which I put in, flattened some, staked, and then put RTV on. Hopefully it won't ever fall out again!
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