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dynodave

B&S 10-13-16hp carbs

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dynodave
I would like to find out what are (if any) identifing features between the carbs (before and after) the 1981 change over date. My 7016 has a date code 92 engine. Yet I think the carb is the original from 75. With 4 carbs from 3410,7013,7016 & now a spare. I have not been able to visually pick out any external identifing feature making them early or late. The repair kits are 391071 for early and 394989 for after 81. Whats the difference with the carbs and the kits? Can I only tell them apart after disassembly? thanks

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RayS
They seem to be the same to me. I have a brand new 10hp 243431 in the box (NOS). Any time I have a problem and think it is carb related. I use that carb to check if it is a carb issue. Since it came off of a 10hp I know that it work on a 10hp. I always use it on diagnosing problems with the 14, 15, & 16hp engines. It always performs flawlessly. They must be the same or very close.

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dynodave
So far I have only seen 2 extra features. 1. the little extra bump in the casting under the idle screw. 2. the choke cable casing clamps some carbs IIRC 2 on rear only.... and some 2 front and 2 rear. but I don't know if they are early/late distinguishing features? internal only? maybe all 4 of my carbs are 2 variants of early

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larry8200
my 78 7013S has the choke cable on the side away from the engine, all the rest are on the inside. The original carb off my 3416H is now on my Big 10, all of my carbs use the same rebuild kit. The 7013S also has a taller paper filter with foam pre-cleaner instead of the oiled foam filter the rest have.


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msiebern
Looking at the two different kits for the old vs. new cutoff, the difference that I noticed was in the high speed jet and emulsion tube. Not sure if that is the only difference, but would be an easy way to identify if it was. Before Changeover Date


After Changeover Date


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HubbardRA
I bought a late model kit, and tried to use it to rebuild the carb from a 243431. The needle valve was solid for the rubber seat, mine needed the needlevalve with a neoprene tip. The other problem was that the emulsion tube was too large to fit into the bore up inside the carb. After that I assumed that I would need the older kit on any future rebuild.

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D-17_Dave
There are a number of carburetor variables that are mostly cosmetic in nature. This will depend on the application of the engine. Some have automatic chokes, inside or outside choke cable connections, choke tension springs or without springs. This is just a few examples externally. There are several variables internal also. The basics include different emulsion tubes, this allows for larger jets for larger displacement engines. There are also float seats that are solid with Viton tipped needles, others have Viton seats with solid needles. These may look interchangeable but are not. As far as the main jet needle goes, the T handle needles are only the old style. Everything made by Briggs at one time used the T handled adjustment screws. All these carbs are interchangeable as far as mounting is concerned and most will run without any problems. They may not be a direct interchange for fuel rates and air flow though so performance will be altered.

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dynodave
Thanks for all your inputs. I suspect since the change over (1981) is after most of the Simplicity/AC machines this forum will deal with that I will assume all of my carbs are the early type. I will buy an OEM repair kit and an aftermarket kit to see if there is any significant differance. The 3410 would not make spark...even after cleaning the points. it feels like a loose flywheel....clunk clunk slop when rotated back and forth. OR a bad rod journal? Last night I got my 7013 engine to fire up on ether :D ...once I diagnosed a bad plug...It would spark in air but not under pressure...tried a different plug and it immediately made noise and smoke. Time to try with a carb and gas. sm06

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dynodave
In the last few weeks I have learned a fair amount about these carbs. There are early and late types...and several variants within those. The basic first difference is the float needle. early- viton tip needle on brass seat (large diameter=.218") late- cheap small bore (.183") needle on replaceable rubber seat. even later has a secondary low speed tansition port /plugged with round shot, just below idle mix screw. your pix does not have it... I am going to try and pull the brass seat body to upgrade to the superior earlier style. The late rubber seat seems to suffer from alcohol fuel. The early style needle/seat are offered for sale as repair parts. There are two emulsion tubes that seem to be common. A "40" for early and a "B" for later. I can see the difference but do not know the performance difference. It seems the cheaper aftermarket are soldered two piece and I found one that had separated/cracked at the solder joint. and was the cause of the fuel leak. The tiny air bleed holes just above the threads easily clog and must be cleared. As stated, pull the emulsion tube before pulling the top off the carb.

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dynodave
I made another discovery though I'd hope most of you seasoned tractor guy know this. Carb leaks/drips: I found that my engine almost always drips at least a little gas out the sintered brass filter after the engine is shut down. Thinking it leaked I had to reclean and reinspect the needle and spray tube seating. So now...Since I leave the fuel shut off--- open it does NOT continue to drip so it must obviously be raw fuel in the manifold/carb back-draining and the dripping is not a leaking needle/seat or fuel spray tube. sm06

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timflury
quote:
Originally posted by dynodave
I made another discovery though I'd hope most of you seasoned tractor guy know this. Carb leaks/drips: I found that my engine almost always drips at least a little gas out the sintered brass filter after the engine is shut down. Thinking it leaked I had to reclean and reinspect the needle and spray tube seating. So now...Since I leave the fuel shut off--- open it does NOT continue to drip so it must obviously be raw fuel in the manifold/carb back-draining and the dripping is not a leaking needle/seat or fuel spray tube. sm06
I recently repaired a carb leak using the "Grind the threads off of an old emulsion tube and using toothpaste, lap the seat, blow out excess, and reassemble." trick and it worked. Briggs has a small Teflon washer you can buy to help seal the emulsion tube seat. And yes, I would most certainly not run these tractors without a fuel shut off. Either inline, or on the bottom of the gas tank. I also shut my gas off before shutting off the engine.

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