Marvel Schebler question.

SouthIL400 · May 8, 2022

Trying to screw in a 90 NPT into Marvel Carb. Hand tight stops at about 6 o'clock. Backing it out to 3 o' clock leaks. What are my chances of getting another 3/4 tight turn to 3 o'clock?
I don't want to split the cast iron carb top. I'm looking for some guidance to make a 90 NPT to a compression fitting.
Thanks for taking the time, it is appreciated.

Steve@Advance · May 8, 2022

If it will hand tighten to 6, it should make it to 3.

If it doesn't feel like it will, the choices are try a random shot at a different fitting, run a die on the fitting, or try to tap the carb deeper.

The only practical way to change the NPT 90 to compression is an adapter or find the correct fitting. Try McMaster or a local industrial hose and fitting supply, should be able to find the correct fitting.

If this is for the carb fitting, it should have a steel line, not copper. If using steel, it needs a steel compression fitting, not brass. Chances are it was originally a flare fitting. You can buy preflared steel line at the auto supply. Intended for brake line, it hand bends well, makes a good replacement.

jimtrs · May 8, 2022

(quoted from post at 13:14:46 05/08/22) Trying to screw in a 90 NPT into Marvel Carb. Hand tight stops at about 6 o'clock. Backing it out to 3 o' clock leaks. What are my chances of getting another 3/4 tight turn to 3 o'clock?

Should easily get at least another full turn from hand-tight. I do all the time when rebuilding carbs. Try a little Teflon tape for lubrication and sealing too.

I'm looking for some guidance to make a 90 NPT to a compression fitting

Sounds like you need a 1/8 NPT(M) x compression (whatever size tubing you are using - 1/4, 5/16, 3/8, etc.)

Any good hardware store should have an array of brass fittings / adapters.

Or to adapt from a 90 degree 1/8 NPT x 1/8 NPT you may already have, use a straight connector

old · May 8, 2022

Is it a brass fitting like i should be?? If yes it will strip out before it will harm the carb

wore out · May 8, 2022

(quoted from post at 10:14:46 05/08/22) Trying to screw in a 90 NPT into Marvel Carb. Hand tight stops at about 6 o'clock. Backing it out to 3 o' clock leaks. What are my chances of getting another 3/4 tight turn to 3 o'clock?
I don't want to split the cast iron carb top. I'm looking for some guidance to make a 90 NPT to a compression fitting.
Thanks for taking the time, it is appreciated.

Since the others have brought up suggestions as to what fitting you are using, may I ask what you are working on?

Several makes of tractors typically used a special inlet fitting with an attached screen, a GOOD thing to have.

If an IH, they used a special "compression nut" that screwed into the carb fitting, standard/generic parts don't match those and won't seal correctly.

SouthIL400 · May 8, 2022

1956 Case 400 (411)

SouthIL400 · May 8, 2022

Yes, just a brass NPT into the Carb. 90* to a 5/16 compression fuel line.

SouthIL400 · May 8, 2022

Yes, Steve, it is a steel fuel line. NPT into the carb, fitting is tight at 6 o'clock. I need it to be at 3 o'clock to meet the fuel line compression fitting at level. 3 o'clock leaks. I am asking for others with experience. Do you believe I can tighten it a 3/4 turn back to 3 o'clock without busting the cast carburetor top?
It is seriously the only leak on the entire tractor, other than a drop of hydraulic fluid in a week.
Thank you!

SouthIL400 · May 8, 2022

Exactly the fitting I have. As I explained steel fuel line is at 3 o'clock, and the fitting is hand-tight at 6 o'clock. Backing it back to 3 o'clock leaks. In your experience can I get another 3/4 turn tight up to 3 o'clock without cracking the cast carburetor top?
I appreciate your time and help.

jimtrs · May 8, 2022

(quoted from post at 15:48:57 05/08/22) Exactly the fitting I have. As I explained steel fuel line is at 3 o'clock, and the fitting is hand-tight at 6 o'clock. Backing it back to 3 o'clock leaks. [b:660b5ae42d][u:660b5ae42d]In your experience can I get another 3/4 turn tight up to 3 o'clock without cracking the cast carburetor top? [/u:660b5ae42d][/b:660b5ae42d]

Are you reading replies?

(quoted from post at 14:03:10 05/08/22) If it will hand tighten to 6, it should make it to 3

(quoted from post at 14:22:14 05/08/22) Should easily get at least another full turn from hand-tight. I do all the time when rebuilding carbs. Try a little Teflon tape for lubrication and sealing too

(quoted from post at 14:39:44 05/08/22) Is it a brass fitting like i should be?? If yes it will strip out before it will harm the carb

YES, YOU CAN TIGHTEN MORE THAN HAND TIGHT. IN FACT, HAND TIGHT ONLY, IS NOT TIGHT ENOUGH.

stevieb49829 · May 8, 2022

Run a NPT die a little further into the carb. Just a little at a time, until your brass fitting can be wrenched down tight at the right angle. Grease on the tap will bring most of the debris out of the hole.

matthies · May 8, 2022

If you wrap teflon tape enough times it will tighten to where you need it. I do this on sediment bowls and it works!!

rustred · May 8, 2022

this is making no sense. tighten by hand then loosen ?? tighten it with a wrench to where u want it. u will break off the brass fitting way before splitting the carb top. are you sure its npt in the carb.

Mike M · May 8, 2022

get some hardening pemetex I think it is # 1 Turn it to where you need it and let it dry. No breakage and no leaks.

Papaw8 · May 9, 2022

The carb inlet will crack if the pipe thread fitting is screwed in too tight. Been there done that on a tractor and screwing a gauge on a well tank manifold. Stupidity on my part trying to get facing the right direction. I think the no. 1 permatex on the threads as mentioned below is the right answer.

SouthIL400 · May 9, 2022

Thank you

SouthIL400 · May 9, 2022

That is the plan.. for now. I ask this because I have cracked an inlet on another tractor before. I don't want to do it again!

Marvel Schebler question.

SouthIL400

Member

Steve@Advance

Well-known Member

jimtrs

Member

old

Well-known Member

wore out

Well-known Member

SouthIL400

Member

SouthIL400

Member

SouthIL400

Member

SouthIL400

Member

jimtrs

Member

stevieb49829

Well-known Member

matthies

Well-known Member

rustred

Well-known Member

Mike M

Well-known Member

Papaw8

Member

SouthIL400

Member

SouthIL400

Member

Similar threads