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2025/06/15 17:57:31

Jchaps20

The mounting bolts shrank- Briggs mower carburetor reinstallment

Hello!

I worked on Briggs and Tecumseh but it was 30 years ago,
so I'm lost.
I bought a carburetor kit for a Troy-bilt LTX-1842 online.

It has a Briggs 16.5 HP I/C engine (331877-0036 G1)

It runs good and mows good but was running hot and the carburetor
Was dropping fuel, so I bought a new one.

I removed the (black intake tubes?) bolts from the engine, removing the
Choke and linkage wire. Loosened the carb mounting bolts and
The carburetor was free.

I put the mounting bolts in the new one, but now the bolts are too
Short. I checked the old carburetor. The bolts are too short
To go from one end of the carburetor to the other, much less
Through the intake system, so now I cannot reattach the new carburetor.

I checked online and no one has ever had issues with these bolts
shrinking before, and admit I've never had luck with repairs,
So I would greatly appreciate any help.
I can pay or offer video or photos if helpful.

I literally just need the carburetor and the two plastic tubes
On either side reattached.

Thank you 🙏🙏

20 comments Leave a comment

Conrad Sigona

I'm sorry. I'm not quite following your story. It seems you're saying that the new carburetor doesn't fit, but are you also saying that you wouldn't even be able to reinstall the old carburetor? Maybe a few pictures would indeed help.

By the way, you say that you replaced the carburetor because the engine was running hot and the carburetor was leaking fuel? I don't see how the engine being hot would be the fault of the carburetor. Are you perhaps running the engine with the cowl off? Are the air passages around the engine clean? As for leaking fuel, it's likely coming from the float valve not seating properly, probably junk in the fuel got stuck in the valve. Take off the bowl and then clean the bowl and the valve seat. In light of the poor quality of many brand-X replacement carburetors, I very much prefer cleaning and keeping the original than swapping it with a new one.

2025/06/15 18:34:53

Jchaps20

I'm sure the smoking muffler wasn't related,but since the fuel smell was very strong and I finally found gas
On the bottom of the carburetor (it did not have an anti-fire plugto disconnect btw), I heard on a video that the
Carb rebuilt kit was only $26, that also came with a new plug, fuel filter and gasket,though I'm very grateful that you
Mentioned the float/seat because that was mentioned in one vid I found.
The carburetor does seem to be a duplicate to the original on the engine.
The problem is the bolts. When I try to put the carb mounting bolts in the breather tube throat, it isn't long enough to reach the opposite end of the carburetor, so I am unable to reattach it. The only possibility is if those adjustment nuts on the mounting bolts are adjustable, andi just moved them further down onto the bolt so that now it will not go back through the breather tube assembly.

I downloaded the owner's manual and it just says "do not adjust the carburetor".
I downloaded the parts manual,but it just shows the carburetor assembly, but no pages or instructions to how it connects
To the breather/intake assembly.
I tried chat GPT, but it just says "re-attach the bolts to the breather throat/nipple/flange".
Since Briggs is now out of business, I couldn't find any other support.

I will try to attach photos again, but it just kept giving the loading icon the last two times.
Thank you thank you for your response!

2025/06/15 19:10:02

Jchaps20

The breather assembly, carburetor and mounting bolt (the end of the bolt just barely reaches the
mount on the left side, and the ridged area on the bolt does not fit through the carb mounts or go through
The breather mounting holes.

I can't reattach the old or new carburetor because the bolts aren't long enough to go through the length
Of the carburetor and also secure the breather assembly on both sides.
I recall detaching the breather throat (right side) with a bolt on the outside and once removed, I saw the tiny nut that is
Attached to the mounting bolt, but unless I use a hammer, I'm not sure I can get the thick threaded areas of those bolts
Back inside the breather tubes to attach to either end of the carburetor.
I tried to attach both photos.

One is the bolt in the old carb and the other is using the new carburetor, so you can see it makes no difference
Which carburetor I try to reattach, there's no connecting the three with these bolts alone

2025/06/15 19:25:04

Conrad Sigona

Can you not reattach the original carburetor?
For photos, if you continue to have trouble, you might be able to upload to a photo sharing site and send us a link.

2025/06/15 19:29:36

Jchaps20

The carburetors seem to be the same size, so I have the same issue getting
Both sides of breather assembly attached to both of them.

I posted the photo of the original carburetor and bolt, so you can see the bolt that I removed
No longer goes into the carb or through either side of the breather tubes.

2025/06/15 20:23:08

SRTsFZ6

Admin, posts are either not showing or posting (my own posts).

Numerous posts just for this thread are showing "approval pending"... ???

2025/06/15 21:29:41

Conrad Sigona

I can see the photos now. There seems to be a knurled bushing behind the nut on the bolt. My guess is that the bushing used to be inside the bolt hole of the plastic part (air cleaner assembly) that fits on the carburetor, or inside the bolt hole of the intake manifold (if it's plastic) as an anchor for the bolt. Examine both to determine which side used to contain the bushing. In either case, remove the bushing from the bolt and fit it back into the plastic. Now the bolt is, so to speak, longer! Examine the inside of the bushing. Does it have threads or is it smooth?

If the bushings were the bolt anchors of the intake manifold, you will no longer be able to secure the carburetor to the manifold unless you first get the anchors to hold tightly to the manifold. But let me not get ahead of myself. Remove the bushing from the bolt and try to figure out how things fit together.

2025/06/16 07:16:11

SRTsFZ6

I think your putting the carb on in-correctly. We can only partially see what's on each end of the carb with your pic's...

The choke side of the carb should be facing the right, (closest to the air filter) as you look at it on the engine.
Choke being the black plastic lever atop the carb.

The intake manifold obviously bolts to the head, then the carb in the PROPER orientation.

Those long bolts would only bolt on one way. I do have to admit, I've never seen
shouldered/splined bolts as what you have.

Do you know if those are factory installed bolts, or the machine is newish to you and someone's
been playing mechanic?

.

2025/06/16 10:42:59

SRTsFZ6

Does that splined part come off (threaded spline) spin off of the bolt?

If so, I believe that spline SHOULD be embedded in the intake manifold (acting as a nut for the long bolts).
Obviously on the side leaving the carb to manifold spot air tight..

If not, please separate the manifolds, bolts, splines, etc so we can figure out what goes where...

.

.

2025/06/16 10:50:16

SRTsFZ6

Does this help?

2025/06/16 11:00:15

Conrad Sigona

Yes, I agree with SRTsFZ6. The carburetor is backwards, and yes, the splines would go into the intake manifold.

2025/06/16 11:01:00

Jchaps20

I can see an imprint of the "splines" on the black manifold mount holes, but those small nuts do not seem to adjust on their bolts, and short of using a hammer, I'm not sure how to get the splines or the tiny nuts on the bolts to fit back into the manifold. I will try to get more photos.

I can't say if the previous owner made changes, but the carburetor was definitely old and used, and everything
Fit together just fine before I removed these three pieces from the engine.

And thank you for the tips!

2025/06/16 11:56:06

Jchaps20

SRTsFZ6
Does that splined part come off (threaded spline) spin off of the bolt?

If so, I believe that spline SHOULD be embedded in the intake manifold (acting as a nut for the long bolts).
Obviously on the side leaving the carb to manifold spot air tight..

If not, please separate the manifolds, bolts, splines, etc so we can figure out what goes where...

No, I've not been able to get the small nuts or splines on the bolts to move.

I noticed yesterday the carb was reversed, but the length of the bolts don't reach both ends with the manifold ends in place. I only took off a nut from each bolt when I removed them, so I just have to find a way to force the splines back inside the manifold mounts

.

.

2025/06/16 12:05:17

Jchaps20

I have photos but they just keep loading and not posting.

. The mounting bolt (splines/flange and the attached small nuts are fixed onto this bolt)
And the entire assembly with the engine bolts I put in on the left to go onto the engine.

I kept all the parts together in a box, so just the nuts are for the opposite ends of the bolts I guess?

2025/06/16 12:26:15

SRTsFZ6

Go to "Post image", which is free, open an account and up load your pictures:

https://postimg

Use the "hotlink for forums" to copy, paste here, and it'll show as a large pic.

Please post all your parts end to end so we can figure out what goes where...

.

2025/06/16 19:51:49

SRTsFZ6

IE:

2025/06/16 19:58:04

Jchaps20

Thanks man! That helps. I copied hotlink to forum and will try to paste the link below.

I encouraged the bolts through the manifold mount with a hammer
for about an hour, with the help of some 3-in-1 oil, so now the bolts
Are now flush with the flange/rim area, but still not extending outside
Of the opposite end of the carburetor.

I used pliers and an adjustable wrench to see if I could move the small
Nuts on the bolts up further to give them more length, but no luck.

So as of now, the bolt end is ALMOST out the other side, and they are
Sticking out about an inch on the left side.

2025/06/16 23:17:02

Jchaps20

Link attempt with parts..

I click the "hotline for forums" icon to the right

It says copied.

I see either a url option or https option to paste.

I pasted 4 photos, but when I click submit or save changes, they vanish and are no longer inside
My reply post.

2025/06/16 23:25:09

Jchaps20

Hyperlink for forum attempt 3

One hour hammer results with 80% bolt target depth

3in1 oil utilitzed with hammer to encourage flange/ridged grooves into manifold/intake
Bolt holes.

Bolts are about 1cm from the exit port on the opposite carb end.

Bolts protrude about 1 inch from their point of entry on left side of carburetor.
(Photo of parts before hammer bolt assistance also included)

2025/06/16 23:39:45

SRTsFZ6

Don't hammer on anything, period.

Those threaded bolts are 1/4" x 20.

There are threads inside the intake manifold where the carb bolts to, correct?

As something definitly isn't right, get some "all thread, 1/4 x 20".

You can measure and cut "longish" for now..

With the 2 new studs, thread them into the INTAKE manifold FULLY, just slightly snug.

Put your gasket over the studs and slip the carb on over the assembly.
MAKE SURE THE THROTTLE PART (METAL) OF THE CARB IS CLOSEST TO THE INTAKE MANIFOLD.

You can very loosely attach two 1/4 x 20 nuts to hold the assembly together FOR NOW.

Slip your throttle linkage the the carbs throttle and choke.

Remove the nuts and slip the AIR FILTER OVER THE STUDS (with the round gasket).
Re-install the nuts, snuggly.

Slip choke linkage into place and make sure throttle linkage is installed.

Bolt the assembly to the head and then once all aligned, tighten the nuts. Small flat washers
would be good under the nuts as the nuts are up against plastic...

.

.

2025/06/17 07:19:47

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The mounting bolts shrank- Briggs mower carburetor reinstallment

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