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Anybody know tap size for main nozzle on Walbro carb?

#1

C

coinman66

I think I can salvage this carb. Boogered up threads on main nozzle in my Walbro 4993 carb. Briggs part # on carb is 799727. Just wanting to know tap size where brass emulsion tube goes.
THANKS!


#2

S

SeniorCitizen

Can you measure the diameter of the threaded portion of the tube with a micrometer?


#3

C

coinman66

SeniorCitizen said:
Can you measure the diameter of the threaded portion of the tube with a micrometer?
Click to expand...

Don't own a micrometer.


#4

reynoldston

reynoldston

if you own a tap and die set run the nozzle through a die first just to get the size. don't be surprised if its a odd size.


#5

C

coinman66

reynoldston said:
if you own a tap and die set run the nozzle through a die first just to get the size. don't be surprised if its a odd size.
Click to expand...


Don't own a tap and die set.


#6

C

coinman66

Wonder if I could contact Walbro techs and they could tell me?


#7

reynoldston

reynoldston

Very hard to work without tools. Maybe bring the nozzle to a repair shop and they will check it out for you. I can't see them charging you very much or anything to run their tap for you. You can buy a cheap tap and die set from HF for around 10 dollars. They work fine for a home shop. get both sets SAE and metric


#8

I

ILENGINE

Don't remember the size but it is an odd size not available in any tap and die set. Briggs has their own carb tap set for cleaning those threads, but I am not even sure it will fit the newer walbro carbs, because the set was originally used for the old briggs carbs used one their engines similar to the 8 horse side shaft, and the carb used on the vertical snapper rear engine mowers.


#9

reynoldston

reynoldston

ILENGINE said:
Don't remember the size but it is an odd size not available in any tap and die set. Briggs has their own carb tap set for cleaning those threads, but I am not even sure it will fit the newer walbro carbs, because the set was originally used for the old briggs carbs used one their engines similar to the 8 horse side shaft, and the carb used on the vertical snapper rear engine mowers.
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Seeing its something I have never had a need for I never gave it any thought. I know in my own mine I was thinking odd sizes but didn't know for sure. Sure sounds like new carburetor time to me.


#10

C

coinman66

reynoldston said:
Seeing its something I have never had a need for I never gave it any thought. I know in my own mine I was thinking odd sizes but didn't know for sure. Sure sounds like new carburetor time to me.
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Nope gonna, gonna try and tap it and fix it. I won't give up without a fight!


#11

reynoldston

reynoldston

coinman66 said:
Nope gonna, gonna try and tap it and fix it. I won't give up without a fight!
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Sounds like something I would do. As for myself there times I have given up after I have take apart and put together a carburetor several times. Give it a try and good luck.


#12

C

coinman66

reynoldston said:
Sounds like something I would do. As for myself there times I have given up after I have take apart and put together a carburetor several times. Give it a try and good luck.
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I'm gonna try and contact Walbro for tap size info. Wish me luck!


#13

reynoldston

reynoldston

coinman66 said:
I'm gonna try and contact Walbro for tap size info. Wish me luck!
Click to expand...

If it is a special tap??? don't be shocked when you hear the price, that is if you can buy one. If It is odd size I have bought some odd tap sizes from Granger.


#14

C

coinman66

reynoldston said:
If it is a special tap??? don't be shocked when you hear the price, that is if you can buy one. If It is odd size I have bought some odd tap sizes from Granger.[/QUOTE
]
I'm sure it's gonna be an odd size. But if they tell me the size, hopefully I can order one somewhere online. It would be good to keep around because I'm sure most all carbs brass emulsion tube are same diameter?
Click to expand...


#15

S

SeniorCitizen

So you have no tools to work with but you do have good common sense.

Let me tell you of some old mechanic tricks. Red Neck micrometer - If you at least have a good adjustable wrench ( cresent ) if you will, you can get real close to the diameter by adjusting the wrench snug to the threads and then without moving the wrench jaw insert feeler gauges until they fit snug within the cresent wrench jaws. Add the total of the gauges and you have the diameter in thousandths.

At the hardware store ( Ace ) find a screw that diameter and lay your threads on top of the screw threads. If they have the same pitch ( threads / inch ) the two will interlock and match perfectly. To make a Red Neck tap of that screw, file a v groove in the screw at about a 30 degree angle at the end effecting the first 3 0r 4 threads. Remove any burrs from filing and there you have a thread chasing tap to correct your screw up.


#16

B

bertsmobile1

SeniorCitizen said:
So you have no tools to work with but you do have good common sense.

Let me tell you of some old mechanic tricks. Red Neck micrometer - If you at least have a good adjustable wrench ( cresent ) if you will, you can get real close to the diameter by adjusting the wrench snug to the threads and then without moving the wrench jaw insert feeler gauges until they fit snug within the cresent wrench jaws. Add the total of the gauges and you have the diameter in thousandths.

At the hardware store ( Ace ) find a screw that diameter and lay your threads on top of the screw threads. If they have the same pitch ( threads / inch ) the two will interlock and match perfectly. To make a Red Neck tap of that screw, file a v groove in the screw at about a 30 degree angle at the end effecting the first 3 0r 4 threads. Remove any burrs from filing and there you have a thread chasing tap to correct your screw up.
Click to expand...

And don't forget cutting a nut in 1/2. linishing the cut faces flat then clamp the 2 halves back on the shaft / bolt and use it to chase the damaged threads.
When you get to bigger sizes a thead chaser can go into 3 figure numbers.


#17

I

ILENGINE

The Briggs tap set was for the 2 piece flo jet carbs, they are 1/4 x 32 and 5/16 x 32 Seems like I have used the 5/16 size on walbro carbs in the past. but it could of also been a standard 5/16 x 24 or 18 thread tap. Been too many moons ago.


#18

C

coinman66

ILENGINE said:
The Briggs tap set was for the 2 piece flo jet carbs, they are 1/4 x 32 and 5/16 x 32 Seems like I have used the 5/16 size on walbro carbs in the past. but it could of also been a standard 5/16 x 24 or 18 thread tap. Been too many moons ago.
Click to expand...

Ok thanks. I will look into these sizes.


#19

reynoldston

reynoldston

ILENGINE said:
The Briggs tap set was for the 2 piece flo jet carbs, they are 1/4 x 32 and 5/16 x 32 Seems like I have used the 5/16 size on walbro carbs in the past. but it could of also been a standard 5/16 x 24 or 18 thread tap. Been too many moons ago.
Click to expand...

Seeing its a 1/4X32 or 5/16X32 you can buy that size taps from McMaster-Carr. That is where I bought mine from.


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