Venturi stuck

[loch]

Hope everyone is having a great Holiday Season!

Actually the main nozzle is stuck as well. I've got some WD-40 soaking into right now. The nozzle moves up and down. But not down far enough to grab it with anything. And the Venturi is stuck as well.

What's the best way to dislodge the Venturi? I'm concerned about scratching the main nozzle tube by forcing the nozzle out with a pick or something.

I'm contemplating getting my plumber's torch out but I'm apprehensive about putting an open flame to the brass body. I used this method of heating when seating the throttle bushings for the Panhead M74. Smaller surface area to heat so I wasn't so concerned about it.

Thanks,
Loch

[T. Cotten]

The nozzle must come out first, of course, Loch...

The venturi can then be pressed out, usually easily.

Since the nozzle will move, there must be "crust" in the nozzle "well" beneath it, and a 38 caliber bore brush should clean it.
Then the nozzle can be pulled with a cable:

NZLCABLE.jpg

Good luck, and Happy Holidays!

....Cotten

[loch]

That was easy, T!

Found an old gun cleaning kit in the garage - from my days in the Navy. Nozzle is out!

The Venturi in the M74 wasn't this difficult to remove. Still working it.

[T. Cotten]

Its hard to hurt it with heat actually, Loch,...

But I refer a heat lamp for other reasons.

CHEMSOAK.jpg

Its best to drift it out the front of the carb, if you can find a puck just shy of 1 3/8" to put behind it.

It is not unusual for the venturi to prove quite loose after cleaning, which is yet another issue.

.....Cotten

[kitabel]

Apparently, my purpose (to provide information) merely exposes me to criticism. You'll find that, in almost every remark I make, someone is compelled to add, find fault, disagree, etc.

Please: have the last word, and explain...

I'll just use the only method available: don't help.

[T. Cotten]

The nozzle OD and body ID are .342”, making a 38 caliber (actually .357") brush a good fit.
The nozzle body center is this size for 1½" (4 bolt) models 1940-49 (M-25, M-75, M-35, M-36, M-45, etc.), in 1949-64 (M36A, M-45A, M-61, M-74B, etc.) the center diameter is reduced to .218".
All 1933-52 1" & 1¼" (3 bolt) models are the early type.
The nozzle ID is .1405" (#28 drill).
Indian (1" and 1¼" only) nozzles are a direct swap with H-D as to size, but have different air correction hole patterns and sometimes smaller ID. If you find on of these, it may be closer to what your modified engine wants than the original, just be careful.

Just to avoid confusion, Folks,...

The "nozzle body center" for the late models is indeed reduced (creating a larger reservoir for acceleration demand), but as shown here on the right,..

nozzls2.jpg

..the square shoulder at the top, and full circumference at the bottom still fit the same bowlstem nozzle 'well', which was the same for all Model Ms.

(Although HD nozzles were fairly consistent, I have logged #27 bores;
Indians used a half-dozen different Linkert nozzles, nearly all radically different from HD's, so I would caution against an arbitrary swap.. But would love to hear the results anyway!)

....Cotten

[loch]

So to be clear, this M31 is mounted on a '32 VL, 3 bolt manifold.

Clearly I have the nozzle pictured in the center. See the last picture here.

What is surprising is that despite the 24 hour solvent bath the nozzle is still covered with carbon. Notice how clean the carburetor body is now. The nozzle being stuck before the bath, I was hoping it would be freed when deposits around the base of the well were dissolved. I must confess, I did not use ultrasound and only depended on the strength of the solvent.

Nevertheless, a little scrubbing with the bore brush freed the nozzle. I was likewise hoping the solvent would free the Venturi as well, this is exactly what happened when cleaning the M74 this past summer. I was expecting the Venturi would drop from its position in the carburetor bore once the nozzle was out of the way. Since this has not happened I will attempt to drift the Venturi out with a puck.

Tom, good idea with the heat lamp, I'll give it try. Seems a little more controlled than open flame.

carbb4cleaning.jpg



carbafterclean.jpg


nozzle.jpg

[kitabel]

Sorry, no longer participating.

[T. Cotten]

I do use a flame, Loch,..

To loosen stuck gallery plugs, by cooking them directly with a jeweler's torch and then cooling them with penetrant.

You will want to soak it again with the plugs removed, as passages will 'airlock' while blocked.

Access for the solvent to the venturi is almost entirely through the open air correction hole behind the idle needle:

M31LFT.jpg

You may need to force-feed it if there is a lot of debris in the annular void around the venturi:

SNDYVNT.jpg

....Cotten
PS: Again to avoid confusion, the plating on the M31 above isn't like the original.

[duffeycycles]

I use a heat gun [or if in a hurry 2 of them] to release galley plugs & nozzles.I use an ultrasonic with heater & simple green/water mix to loosen crud,especially on pesky CV carbs that backfire & fill with carbon.Another method is a used slow cooker.

[T. Cotten]

Some nozzles are harder to pull than others, Folks!

NZLPULLR.jpg
(GX Scheblers are the worst, but I've had to drill out a potmetal DLX or two, always for a Four.)

....Cotten

[loch]

Thanks for the information and guidance, Tom!

I'm soaking the carburetor with ALL plugs removed this time. I'm afraid the Venturi might end up looking like the one in your picture.

I have an off-handed question about the various main nozzles and their purpose. Your picture shows vent holes of various quantity and size. I'm sure this will effect the mist of fuel that makes it to the throat. What if any affect does this have on which nozzle to use? Or, is there a specific nozzle to use for a specific carburetor?

Thanks,
Loch

[T. Cotten]

Any other nozzle than your original design, Loch,...

Would be an experimental risk!

Please clean your hardware and inspect the nozzle spigot for wear, and the corresponding hole in the venturi:

spgtvent wear.JPG


A poor fit of the two defeats the 'accelerator sump' function, but can be remedied by soft-soldering the spigot and carving it to fit the hole.
Minor wear is easily accommodated by a thin PEEK seal.

NOZLSEAL.jpg

I am only a student of these things, so I must defer to the Armored School Handbook to explain nozzle functions:

accltxt2.jpg

.....Cotten

.

[duffeycycles]

I always heat before removing the venturi.I should mention Simple green & some carb cleaners will darken the carb if left in too long,[worse on aluminum].

[Steve Swan]

Any other nozzle than your original design, Loch,...

Would be an experimental risk!

Please clean your hardware and inspect the nozzle spigot for wear, and the corresponding hole in the venturi:

spgtvent wear.JPG


A poor fit of the two defeats the 'accelerator sump' function, but can be remedied by soft-soldering the spigot and carving it to fit the hole.
Minor wear is easily accommodated by a thin PEEK seal.

NOZLSEAL.jpg

I am only a student of these things, so I must defer to the Armored School Handbook to explain nozzle functions:

accltxt2.jpg

.....Cotten

.

Tom, could you share a bit more about the "Armored School Handbook?" If it's possible, i'd like to find a copy for my reference library.