old briggs walbro LMT carb clean up

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  #1  
Old 10-15-06, 12:04 PM
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old briggs walbro LMT carb clean up

hello everyone i have an old snapper rider with an old vertical shaft briggs on it and i need to clean out the carb real good it is an old LMT walbro with removable brass pilot screw on the top by the mix screw

i need to know how the pilot screw works what they were for and how to adjust the mix screw properly on these and how to properly disassemble and clean these carbs up real good so i can take care of the stumbling it has sometimes while i am mowing


thanks for anything
 

Last edited by fast68; 10-18-06 at 08:54 AM.
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  #2  
Old 10-15-06, 11:16 PM
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The best thing I can reccomend is to remove the carb, disassemble it, and soak it in a bath-type carb cleaner. Replace the inlet needle and seat if it has a rubber seat (some had brass seats with viton-tipped needles, others had aluminum needles with rubber seats). Check the wear at the throttle shaft. The throttle shaft and carb housing often wears enough to cause performance problems. The nozzle you refer to basically helps atomize the fuel coming from the main jet into the carb throat near the venturi. The mixture screw should be set around 1 1/2 full turns out from lightly seated. Fine tune if needed at idle speed.
 
  #3  
Old 10-17-06, 03:24 PM
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awesome great info i appreciate

yeah this one has the aluminum needle with red rubber tip it looks in really great shape no damage or wear visible at all but i was told that if its leaking it can cause the fuel tank to go dry when it sits and it does do this, so hmm

on the pilot screw atomization thats interesting to know

is there somewhere i can read about how this works or is it real easy to explain ?

also the hole through the end of this screw is it supposed ot be in aligment with the tube that runs through the carb housing to it ? or does it not matter ?

when i pulled the bowl i found it to be VERY rusty and chunks of rust and flakes in it, tons of it

what do you do to prevent this from happening ?

the bowl itself is rusting, the tank is plastic and so it cant be from that or anything else,

can i tin or coat it somehow ?


thanks!
 
  #4  
Old 10-17-06, 03:52 PM
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I messed up in my previous post, I was thinking about an old flo-jet carburetor, I see you have a LMT series., but your description made me think it was a flo-jet.

What is the Model and Type number of your engine, I will see if I have any service Lit on your carburetor for you.
 

Last edited by 30yearTech; 10-17-06 at 04:05 PM.
  #5  
Old 10-17-06, 04:42 PM
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I see...I made the same mistake too. I was thinking Flojet carb. I assume the pilot screw you're talking about is the short brass screw at the side of the top of the carb. If I recall correctly, this is the idle jet.

I still reccomend replacing the needle/seat, but the float on these should be plastic, and they rarely go bad. The rust in the bowl was cuased by water in the gas. The carb is the lowest spot in the fuel system, and water is heavier than gas, so it goes straight to the bottom of the bowl and sits there. If you get the rust cleaned out of the bowl, it may be so far gone that it leaks...so replacement might be the only option. I wouldn't try to fix it...you can get one for a couple bucks.

The initial setting of the mixture screw would be the same as described earlier.

The throttle shaft problems I mentioned don't usually appear on the LMT carbs.

It doesn't matter where the hole in the tube is pointed on that "pilot screw"...just put it all the way in snug.

There are a few variations of this carb, so some details may differ according to which one you have.
 
  #6  
Old 10-18-06, 03:11 AM
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Briggs has a very comprehensive book on small engines. It covers carburetor operation very well. The Briggs part number is CE8020.
 
  #7  
Old 10-18-06, 05:51 AM
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so you can get new bowls for these??

its a 190702 and 0629-01 and 7202220

old 8 horse briggs, like 1972 year or so im thinking

it has nylon float yes

pilot screw on these is brass and has the hole across the end and it screws straight down into the top of the carb right by the air mix screw with the spring on it

here is exactly what i have:

http://img.photobucket.com/albums/v298/fast68/RandysWorld/walbr.jpg

i assumed everyone knew what the old LMT briggs carbs were, oops


the 1991 14 horse twinII briggs i was talking about towards the end of my original post is a whole different mower than this old 8 horse with the walbro on it that i am cleaning up


thanks
 

Last edited by fast68; 10-18-06 at 09:26 AM.
  #8  
Old 10-18-06, 06:31 AM
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Red face I am stumped ???

Well the model number of your engine shows an old Briggs Flo-Jet carburetor on it. The picture of the carburetor you have listed in your link I don't believe was available on engines manufactured in 1972 as this is a much newer carburetor.

It sounds like the screw you are talking about is the main jet, it is hollow and screws down into the nozzle and feeds fuel up through it to the low speed circuit of the flo-jet carb.

If the carburetor you have on your machine is the same as the one pictured, someone must have modified the original engine. The pilot jet in this carburetor is as cheese described, it is the jet for the idle circuit and the screw next to it is an air bleed and used to adjust the idle mixture.

Like cheese was talking about in his post the throttle shaft on the flow jet was subject to wear, it was mounted horizontal through the throat on the carburetor and the intake manifold was incorporated into the carburetor design.

The carburetor in your picture has the throttle shaft mounted vertical in the carburetor and the carburetor mounts to an intake manifold. I don't think this design was around until some time in the 90's, I could be wrong but I sure don't rember any of these in the 70's.
 

Last edited by 30yearTech; 10-18-06 at 06:44 AM.
  #9  
Old 10-18-06, 07:38 AM
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I agree there is way too much plastic on that carb to have been made in the 70's

The manual Puey mentioned would be a good resource, although you can view and exploded Illustrated parts list here http://www.briggsandstratton.com/display/router.asp?docid=78484 using your engine #'s you posted to view the carb it shows should be used. Possibly a retro by briggs??? or snapper???
Perhaps a bit more description on the "stumbling" symptoms you mentioned, could help to address the problem or nuisance...?
 
  #10  
Old 10-18-06, 09:27 AM
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hum well i dunno, the pic URL above i posted is the identical same carb as on this old 8 horse snapper, it took me a while to find it online lol

and mine has the separate intake manifold yes, it is also bare aluminum casting like the carb is


it all matches and looks stock correct to me, hmm

wierd.

way too much plastic ? huh ?
the only thing plastic on it is the inlet and the float,

thats all, well and the throttle or choke linkage plate

its a really old twist style chassis red snapper it is snapper all the way it stil has the chassis tag on it riveted and everything

why cant this carb have existed back then, it is an old style aluminum carb, it looks as old as the 70s to me, hmm,,

i dont see why its wrong to be on this old of a mower, but then i am an auto mechanic and by no means whatsoever small engine knowledgable, so..


i do have a '70's years engine right ? no ?

im not the only one who runs into wierd stuff right ? this was all supposed to be simple lol


anyways the symptom is that it stumbles sometimes when its hot after having run it under load for a while it will start to act like it is running out of gas and will die down pretty much til it dies, for no reason at all

it used ot never do it and its been getting more and more often last coupel of months

maybe its the points getting hot ?

i dunno ?

theyre probably original, who knows

strong running engine otherwise


thanks again
 
  #11  
Old 10-18-06, 12:37 PM
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The fact that it has ANY plastic at all on it leads me to believe it is much newer than 70's vintage.

It sounds like possibly the carb may be running too lean...have you adjusted the mixture setting as cheese mentioned above...?
 
  #12  
Old 10-18-06, 12:38 PM
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If you post the model of your snapper, we can probably determine what vintage and what engine is spec'd for it.
 
  #13  
Old 10-18-06, 03:23 PM
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Maybe someone put an old starter housing on a newer engine?

Check the fuel cap on the gas tank, make sure the vent screw is open, the fuel caps on older snapper riders had a manual vent that could be closed. If it runs for awhile then acts like it's running out of fuel that could be it. If the vent is closed then it will create a vacuum in the tank and it will run out of fuel.

You can download a "pdf" of your engine break down at the link listed below, and you will see the carburetor we all thought you had.

http://shop.briggsandstratton.com/BShopProductListingPage.asp?rsvp=0&PARENTID=0&SessionID=43C7B3A0-6A44-4EB2-B2CC-23B437198A68&MECID=100&CATALOGID=56B2B9A7-283C-11D4-8886-00B0D0203414
 
  #14  
Old 10-18-06, 06:59 PM
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howdy thanks

it has a red plastic square/rectangle tank i tried running it without the cap, it changes nothing

ill see about adding numbers off the mower chassis yeah, if i can get a chance to, i dont see the tag now i cant remember where i saw it on the thing now, hmmmmm lol


i appreciate
 
  #15  
Old 10-19-06, 12:54 AM
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According to the numbers you posted, it is a 1972 engine, or at least the shroud with the numbers on it is from a 1972 engine. That carb was not made or available until more than a decade after that. I believe someone either used the shroud off of an old engine on a newer engine...OR...swapped carburetors. To swap from the old flojet to this one, you pretty much have to swap the throttle control box on the side of the engine and the governor arm as well. One way to tell is to look at the bottom left mounting hole on the throttle control box, facing it directly. If there is no mounting screw in that hole, and no hole in the block or casting place for a hole, then that engine is old, but the carb is newer. Also, the original briggs engines used by snapper in '72 were painted white.

In any case, it appears you have the new style carb. I don't know that I would suspect the carb for your symptoms though. Does it have points for sure?
 
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Old 10-20-06, 12:46 AM
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howdy there,

yes this engine is white, no evidence of any other color under it, or of any repaint job ever,

it all looks to be around 72 vintage, and even this LMT carb in question too, nothing is rigged or hacked or anything else at all in any way anywhere on this engine and mower that points to any possibility of it having been converted or anything else,

for real

i dont think there's a screw or hole where you are describing but i could look and verify, because i am just not for sure off the top of my head now



so LMT didnt exist yet back then or what ?

when were these carbs first made ?


hmm..

also could i use the flywheel and starter off a 1992 or so 8 horse rider, same configuration engine and all that, even has the same control plate assembly design as this old white 8 horse in question

im tired of the old pull start, it has its problems sometimes and im tired of having to remove the starter housing all the time to re-string/unjam it and such when it messes up on me often

oh and how would a 1972 briggs not have points ?

how else could it make spark ?

it has a normal ignition coil and single wire to the control plate assembly like any other old points euipped engine, and thats all it has, nothing else, no other wires or anything else, its normal old style stuff



thanks again
 

Last edited by fast68; 10-20-06 at 01:09 AM.
  #17  
Old 10-20-06, 01:46 AM
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No, that carb wasn't available back then.

Yes, it could have something other than points. Just because (if) it is a '72 engine doesn't mean the coil has never been replaced. The replacement coil has a solid state ignition module on it. The newer coil would have a single wire also, like you described, going to the throttle control box, so there's no way you'll know if it has points or not without looking at it yourself.

Yes, you can use the starter and flywheel off the newer engine. You'll also want the alternator.
 
  #18  
Old 10-20-06, 07:55 AM
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hmm interesting

they have an alternator on the electric starter equipped ones ?

where is it ?

wow these engines are way complicated


dang

im definitely sticking with automobiles, wow

these things are just too much, what a pain :O


thanks
 
  #19  
Old 10-20-06, 10:40 AM
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If this engine has an alternator, and it likely does, it will be under the flywheel. Along with the stator plate - mounted to the block - there will be a series of magnets on the inside of the flywheel for the generation of power. As for the carburetor, it is highly unlikely that it is original. The Walbro's weren't used on Briggs until the mid to late eighties. This means that you'll have to figure out what kit you need since you have no ID numbers to go with the carburetor, other than the fact that it is an LMT series carb. There is not necessarily only one kit available for this series carb so you'll want to find an established, reliable Briggs dealer in your area for their opinion on the kit needed. Good luck.
 
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Old 10-23-06, 10:48 AM
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ok good info, ive learned quite a bit very interesting


so definitely not original carb and is a later one, and the system could be points or not

interesting

hmmm

is there no way at all to tell what system it has without pulling the flywheel ?

can i figure out if it has magnets in it without pulling it

cuz if it has no points then i have no reason to continue to try to remove the flywheel if theres no points to replace in it

in which is what i was planning on doing

if so equipped

thanks again
 
  #21  
Old 10-23-06, 12:45 PM
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Look for a wire leading from the coil to area underneath the flywheel, if there is no wire connected to the coil leading under flywheel then unit could have been upgraded to a magnetron ignition.

Early conversions had a little clear or white plastic solid state triggering unit attached to one side of the coil assy. Complete magnetron systems have the triggering unit molded into the coil assy. and one side of the coil winding is offset and squared off.
 
  #22  
Old 10-23-06, 01:40 PM
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ok i looked and theres a magnet piece inset into the flywheel outside diameter

and the top side of (where the air fins are on the flywheel) this magnet piece is aluminum and has its own few air fins- heres a pic of exactly what i have http://i17.ebayimg.com/01/i/08/bd/5e/ab_1.JPG

the wire from the coil goes down to the control cable panel assembly and no wire goes under the flywheel area and instead there is a wierd white plastic contraption/piece of some kind -mounted to the coil closer to the flywheel side of the coil-

and a part of this plastic piece extends below and under/into the flywheel area and looks like it probably sits just inside the flywheel inside diameter area

otherwise the coil looks like any other ordinary old style coil i dont notice anything offset or anything like that, hmmm but i guess i dont know what you mean by that actually :P

what do you think ?

this must not be a points controlled engine ?
right ?

i wish i could finx an xD pic card reader for my fujifilm 2650 digicam hmmm

anyone know of one anywhere?

thanks again
 

Last edited by fast68; 10-23-06 at 07:00 PM.
  #23  
Old 10-23-06, 02:13 PM
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also i have an engine i saved off another riding mower it is
281707
0317 01
87093011

12 horse I/C vertical shaft also same as this old snapper 8 horse

should i be able to use the flywheel and starter motor on the old snapper one ?

how can i check beforehand ?

if i can then i will weld up a battery box for it on the chassis somewhere and do it right

also how do you connect the battery to the engine to keep it charged ?

thanks some more
 
  #24  
Old 10-23-06, 03:06 PM
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The "white object" on the coil is an early style, add-on, Briggs Magnetron solid state module. With this you'll have no points and condensor. As for the other engine you have, my lookup shows no such model AND type, recheck these numbers. Before we get into wiring for battery charging, lets see about the spare engine first.
 
  #25  
Old 10-23-06, 03:08 PM
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Sounds like a magnetron conversion kit was installed on your coil. I don't think you have to look for any points.

Look up both engine break down's at the link I listed earlier and see if both flywheels have the same part number, then they would be interchangeable. I still think that they will both work as far as making the engine run, but there could be a difference if one engine has electric start and an alternator and the other engine does not, then one will have additional magnets on the inside of the flywheel and a ring gear attached to it, while the other may not.
 
  #26  
Old 10-23-06, 08:35 PM
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The flywheel on the 12horsepower engine is larger diameter than the one on the 8. The alternator and starter should be the same though. You'll just need a flywheel with a ring gear.

The battery on the old snappers mounts under the seat to the left side...the metal is made for a small engine battery to fit in place snugly.

The charging wiring depends on what style alternator you have. In either case, the red wire (possibly the only wire if yours is a single alternator) is the wire that goes to battery positive. The diode in line must remain in place. Very simple.
 
  #27  
Old 10-24-06, 10:17 AM
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hi there yeah the 12 horse engine i salvaged off another rider is electric start, i have the entire thing, starter motor and all

the 12 horse electric flywheel is thicker than the 8 horse manual one, but both are right about 8.5" diameter, and both have the same coil and other parts, same engine in appearance other than HP rating and color but then i am really unsure what HP rating the old white snapper engine is

the snapper has no red wire, and none at all cept the small black one from the coil to the cable control panel

thats it

and no place under the seat anywhere for a battery,

its one of those old timer red and white snappers with the round tube type steering handle/bar

but then i just assume it is an old snapper that is just what a couple ppl have said it was thta have sene it and i know where another one just like this one is sitting at just across from my brothers place just outside of town


i didnt think any of these were fitted with electric start engines,
it seems too basic of a chassis to be electric



hmmm

again i wish i had the card reader i need for my digicam,


thanks again
 
  #28  
Old 10-24-06, 05:36 PM
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http://www.snapper.com/#

Go to the above listed website and click on publications, on the selection drop down under model select 3080S and under manual type select operator then click the search button. A pdf will download that I believe is very close to the model you have. when you are looking at the chassis you will see the area directly under the seat, there is a channel here on both the right and left sides with just enough room for a standard lawn and garden tractor battery to be placed. On the newer models there was a bracket that bolts to the outside of the frame that holds the battery in place, I don't remember what held the battery down on the older models.
 
  #29  
Old 10-25-06, 12:30 AM
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Correct...there is a place under the seat...and many if not most all of these (even the old ones from the '60s and '70s were electric start. Basic, yes, but so was the electric start system. Didn't even use a solenoid. From the factory (on electric start models) the battery was located on the left side, and the starter button was on a panel over the channel on the right.

If the engine is the same dimension wise as the 12 horse, then it's not an 8 horse. The numbers you posted are for an 8 horse, but the 8 horse is shorter. The flywheels do have the same diameter (about 8.125") although the design is different. I don't know if the 12hp flywheel will work on an 8hp engine or not. What's wrong with the 12hp engine? Why not just use it?
 
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