IH Carb Inlet Threads

Farmall Cub Forum -- Questions and answers to all of your Cub related issues.

Moderator: Team Cub

Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
User avatar
Don B.
Cub Star
Cub Star
Posts: 142
Joined: Thu Jul 02, 2015 12:02 pm
Zip Code: 25314
Tractors Owned: 1951 Cub
1948 Cub
Circle of Safety: Y
Location: Charleston, WV

IH Carb Inlet Threads

Postby Don B. » Tue May 16, 2017 6:56 am

So when I bought my '48 Cub in pieces, the carb was literally just handed to me. There was no fitting in the inlet. It looked to be in decent shape so I cleaned it up, put a kit in it and set it aside. A couple days ago, I went to put on the fuel line and realized the inlet threads were way too big for the compression fitting. Turns out they are 9/16-18 rather than the 1/2-20. :? I suppose they were changed at some point but they must have done a good job because you can't tell.
So far I have not found a fitting that will connect the 9/16-18 inlet to the 5/16 steel tubing.
Does anybody know of a source or another option?
Thanks.
Circle of Safety

User avatar
Don B.
Cub Star
Cub Star
Posts: 142
Joined: Thu Jul 02, 2015 12:02 pm
Zip Code: 25314
Tractors Owned: 1951 Cub
1948 Cub
Circle of Safety: Y
Location: Charleston, WV

Re: IH Carb Inlet Threads

Postby Don B. » Tue May 16, 2017 7:11 am

Would this fitting be the easiest fix?
Hopefully, the text is readable.
fitting.PNG
Circle of Safety

User avatar
Shane Nelson
501 Club
501 Club
Posts: 2995
Joined: Wed Nov 22, 2017 6:24 am
Zip Code: 27284
Tractors Owned: .
1947 Circle Cub #1447 (Arnold)
195? Cub
1970 International 140 (Norman)
1949 John Deere A
1972 Schramm Pneumatractor
1993 Ford 4630 W/Loader
1965 John Deere 110
1961 Cub Cadet Original
Circle of Safety: Y
Location: Oak Ridge, N.C.

Re: IH Carb Inlet Threads

Postby Shane Nelson » Tue May 16, 2017 7:15 am

I would say they are 1/4"-18 pipe thread, that puts you close to 9/16". Depends on what tap was used rather they are straight or tapered though. If a tapered tap was used you have to grind the end of the tap off to get better threads because the hole isn't deep enough, I have a ground off tap :) You have to take about 3/8"-1/2" off the tap if it's tapered. Here's the tap, a new one on the left and ground one on the right.
Attachments
IMG_6457.JPG
God is good, all the time!
Every home is a school, what are you teaching?
Circle of Safety

Gary Dotson
Team Cub Mentor
Team Cub Mentor
Posts: 3093
Joined: Thu Aug 03, 2006 6:20 am
Zip Code: 43358
Tractors Owned: 48 Cub Diesel (Cubota)
53 Cockshutt 20 restored (Shooter)
52 Cockshutt 20 unrestored
47 Leader "B" (Herckie)
49 Leader "D" (Princess)
49 Leader "D" very rough
48 Leader "D" unrestored
Kubota B6200E
Kubota B6200HST
Kubota B8200HST-D
Circle of Safety: Y
Location: OH West Mansfield

Re: IH Carb Inlet Threads

Postby Gary Dotson » Tue May 16, 2017 7:28 am

Don, I have to agree with Chipmaker. I've seen a lot of Cub carbs, where a 1/4" pipe fitting has been cobbled into the inlet, usually because the owner did not know the difference. If it's trully 9/16 x 18, you should have little problem finding a brake line nut that will thread in. It will be either 3/16" or 1/4" tube and could be drilled & champfered to fit your 5/16" line. I'll look to see if I have one.

User avatar
Ken (48 Cub)
10+ Years
10+ Years
Posts: 868
Joined: Mon Feb 03, 2003 11:10 am
Zip Code: 40023
Tractors Owned: 1948 FCub
Circle of Safety: Y
Location: KY, Fisherville

Re: IH Carb Inlet Threads

Postby Ken (48 Cub) » Tue May 16, 2017 8:21 am

Usually they are boogered up by screwing a fitting made for a rubber gas line, mine was. Helicoil it.
Ken, Annie the '48 Cub & Marie the '57 Loboy.

I think we gotter if'n she don't kick, Andy Griffith.

User avatar
Don B.
Cub Star
Cub Star
Posts: 142
Joined: Thu Jul 02, 2015 12:02 pm
Zip Code: 25314
Tractors Owned: 1951 Cub
1948 Cub
Circle of Safety: Y
Location: Charleston, WV

Re: IH Carb Inlet Threads

Postby Don B. » Tue May 16, 2017 8:45 am

I'm curious. If it was changed to the 1/4-18 pipe thread, why not stay with it?
I suppose there is a reason.
Circle of Safety

User avatar
Shane Nelson
501 Club
501 Club
Posts: 2995
Joined: Wed Nov 22, 2017 6:24 am
Zip Code: 27284
Tractors Owned: .
1947 Circle Cub #1447 (Arnold)
195? Cub
1970 International 140 (Norman)
1949 John Deere A
1972 Schramm Pneumatractor
1993 Ford 4630 W/Loader
1965 John Deere 110
1961 Cub Cadet Original
Circle of Safety: Y
Location: Oak Ridge, N.C.

Re: IH Carb Inlet Threads

Postby Shane Nelson » Tue May 16, 2017 9:00 am

Don B. wrote:I'm curious. If it was changed to the 1/4-18 pipe thread, why not stay with it?
I suppose there is a reason.

Both of mine have been converted to 1/4"-18 pipe thread and I've had no problems with them. Whoever owned them before me tapped them that size, I only cleaned them up and sealed them good. I don't care what size thread is in mine as long as it doesn't leak :D
God is good, all the time!
Every home is a school, what are you teaching?
Circle of Safety

staninlowerAL
5+ Years
5+ Years
Posts: 3471
Joined: Fri Oct 29, 2010 11:34 pm
Zip Code: 36558
Tractors Owned: Cubs: (3)'49's, (1)'52, (1)'57 IH Cub LoBoy w/FH, (1)'72 154 Number Series Loboy, '76 Longstripe w/FH, Mowers: C-22, Bush Hog 412, Pennington 59, Woods RM42CF, Woods 42, assorted FCub plows, planters, discs, etc. OTHERS: '49 AC B & Ind. Sickle mower, '61 AC D12 Ser 2, '52 8N, '56 Ferguson 35 Deluxe, '53 MM BG (offset), (2) '49 Avery V's, '51 JD M (regular), '56 JD 420C, with Blade and fire plow, '85 JD 850 (Yanmar) w/72" belly mower, '76 Yanmar 1500, Sears Surburban's, MTD's, Jeeps & other misc. "treasures"
Circle of Safety: Y
Location: AL (Southwest)

Re: IH Carb Inlet Threads

Postby staninlowerAL » Tue May 16, 2017 9:24 am

Agree with Chipmaker. If the 1/4" pipe fits well, a 5/16 compression x 1/4 pipe adapter fitting can be installed with sealer and you're back to the correct size steel line with a ferrule. Makes it easier to remove the line later without having to deal with the possibility of cross-threading into the soft metal of the carb.

User avatar
Don B.
Cub Star
Cub Star
Posts: 142
Joined: Thu Jul 02, 2015 12:02 pm
Zip Code: 25314
Tractors Owned: 1951 Cub
1948 Cub
Circle of Safety: Y
Location: Charleston, WV

Re: IH Carb Inlet Threads

Postby Don B. » Tue May 16, 2017 12:21 pm

Alright, the threads are, in fact, straight 9/16-18 size. Definitely not a pipe thread even though I had convinced myself that they must be.
So now my plan is to take a brake line fitting which matches the threads and modify it. The closest brake fitting that NAPA had included a short piece of 1/4 inch flared tubing. I will remove the tubing and drill it to 5/16. Then I will "countersink" the end so it can receive the 5/16 ferrule.
Although I am no Chipmaker, I think I can make that work. :|
I will let you know what happens.
Thanks.
Circle of Safety

Bob McCarty
Team Cub
Team Cub
Posts: 8834
Joined: Tue May 25, 2004 8:02 pm
Zip Code: 80501
Tractors Owned: Cubs, MH Pony, Shaw, Allis G, 1934 Silver King, JD LA and LI, Gibson D, David Bradley Tri-Trac
Circle of Safety: Y
Location: CO, Longmont

Re: IH Carb Inlet Threads

Postby Bob McCarty » Tue May 16, 2017 4:17 pm

If the fitting looks the same as the 1/2-20, you can probably just cut the flare off, enlarge the hole and use a 5/16" ferrule that seats inside the carb inlet. I don't think you need to countersink anything unless I'm misunderstanding what you have....
"We don't need to think more,
we need to think differently."
-Albert Einstein

Matt Kirsch
10+ Years
10+ Years
Posts: 4591
Joined: Tue Jun 08, 2004 3:04 pm
Zip Code: 14559
Circle of Safety: Y
Location: Rochester, NY

Re: IH Carb Inlet Threads

Postby Matt Kirsch » Wed May 17, 2017 2:31 pm

I think I used a double-ended compression fitting to fix mine. Take the nut and ferrule off one end and it had 9/16-18 straight threads as I recall. The threads were pretty much gone so I ended up JB Welding the fitting into the carburetor.


  • Similar Topics
    Replies
    Views
    Last post

Return to “Farmall Cub”

Who is online

Users browsing this forum: Bob McCarty, BullDAWG, ericofmaine, Flemmingth, Scrivet and 7 guests