B/C/CA Zenith Carb?

I need to chase the threads in the top casting for a new Fuel Valve seat. I need to know the correct tap size to use.

I have several complete Zenith carbs that are externally bass-ack-wards. Don't know what they fit. Are the internals all the same? Thinking of using them if I have enough correct "for AC" shaft assemblies and can get fuel IN at the front. Some appear to have 3 IN positions. Front, Back and End. Not sure if all INlets have threads. One I'm thinking just has a flat brass plug.

Steve. The fuel inlet tap size I knew. Its the inlet Valve Seat Thread size I have a question about.

I did take a valve seat to Fastenall yesterday after posting to get a matching tap. After about 30 minutes of trial and error, it was just as I figured. It is a special thread. There is only one tap and it must belong to Zenith Inc.

Fastenall can get close but not spot on. Turns out only 2 common standard thread sizes are close , A metric 10 and a 3/8-24 both are loose fitting but snug up when the shoulder on the valve seat makes contact. I bought a new 3/8-24 bottom hole because it fit a little less loose than a M-10. I will let you know how it works out after I use it.

Steve

I beg to differ with you on the needle valve fuel inlet seat having the same size threads as the external fuel inlets to the carb and other external tapped openings.

All you have to do is measure OR try to thread the valve seat into a !/8 NPT hole. The valve seat measures .348 across the threads. Thats about exactly the ID of a female I/8 NPT fitting. A 1/8 NPT male fitting measures across the threads .396. A Valve seat fits loose in a 1/8 NPT tapped hole without touching the sides.

How do you logically manage to straighen up the valve seat threads with a 1/8 pipe tap when they are so obviously different?

By the way the 3/8-24 tap worked OK and I could use the Zenith Core I had. A little loose threading in but the seat tightens up OK when the shoulder contacts the gasket. A little research and a clue or two from DickL on straight pipe threads for special applications still hasn't turned up the actual tap size for the valve seat threading.

You being in the business of Carb restoration should be able to find out what special #tap correctly matches the valve seat threads.

DickL

I looked up "Treasured Tap" in all the Catalogs I have and on several internet sites. No such animal listed. lol

I'm sure glad I didn't use a 1/8 NPT pipe thread tap like Steve uses to straighten up those treasured tap threads. I would need to have used JB weld to hold the seat in.

Lesson Learned

Don't ever assume anything from all the answers you get to Questions on the forum.

Ken - I don't see anywhere where you gave Steve the model number for the specific Zenith carb you were working on. He asked you for the carb ID and later gave you a generic answer without the benefit of the model info. While it's possible Steve made a mistake or typo, I'm sure his answer is accurate for many other carbs, obviously just not yours. Steve gives out lots of FREE expect advice on carbs & electrical on this forum. I can certainly understand your frustration in having an oddball problem but dinging people who are trying to help is going to turn people off to wanting to answer questions. Just my 2 cents. Mike

1981 Gleaner F2 Corn Plus w 13' flex
1968 Gleaner EIII w 10' & 330
1969 180 gas
1965 D17 S-IV gas
1963 D17 S-III gas
1956 WD45 gas NF PS
1956 All-Crop 66 Big Bin
303 wire baler, 716H, 712H mowers

Hi guys!
It took me a while to get back on the forum here, but been busy at work with the weather Mother Nature is dealing us. When you work for a utility, things can get a little crazy. Whew! Ken, I apologize if you felt that you were misled on the thread size, but as I said, that's what I use to straighten or remove heavy rust from the seat threads both on the Marvel as well as the Zeniths. An 1/8-27 tap is what I believe it is. Haven't had a problem where a seat was loose, and I've done a couple of those Zenith carbs over the years. I don't know, can't explain it. Maybe my tap is worn? On the carbs that don't have a lot of rust in the threaded area, I use a tiny wire brush in the end of my portable hand drill to run in and walk out a few times. Gets the threads nice n' clean. That same brush I use in the inlet port also. Works great for removing that trapped rust, pipe tape, and debris in the threads and at the back of the inlet. There very well could be a special straight line tap for those particular threads as you and Dick L presume, but the tap I have seems to work fine for getting things straighten out or cleaned... Sorry, just trying to help ya out there.....
Steve@B&B

Steve@B&B

Next time you rebuild a B/C Zenith please remember this thread cause its all about threads. Thread a valve seat into a nice clean 1/8 NPT threaded hole and give us a honest report. No need to try to thread a 1/8 NPT pipe thread fitting where the valve seat goes. I don't want you to mess up any threads.

Oh. After that explain to DickL and I what the meaning of Presumptuous is. We certainly don't want to be the O'Reilly word for the day, "Presumptuous"

Like I said above. I solved the crappy seat thread situation with a 3/8"-NF 24Thread bottom tap. But that still don't make it the right tap for the job and I would discourage others from doing as I did just because it worked for me.

I thank you for trying to help a fella out. A guy with your excellent connections can probably solve the valve seat thread dilemma and come up with a size thread cut by what DickL calls a treasured tap.

Be carefull out there. Mother Nature and her weather can be cruel at times. K in TX

Thanks Steve

I'm Gone Trout Fishin. Wish me Luck. It ain't every day you can do this in NE TX. I can smell that apple wood smoke already and haven't caught any yet.

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Ken in Texas Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Henderson, TX Points: 5919	Post Options Post Reply Quote Ken in Texas Report Post Thanks(0) Quote Reply Topic: B/C/CA Zenith Carb? Posted: 07 Dec 2009 at 3:04pm
	I need to chase the threads in the top casting for a new Fuel Valve seat. I need to know the correct tap size to use. I have several complete Zenith carbs that are externally bass-ack-wards. Don't know what they fit. Are the internals all the same? Thinking of using them if I have enough correct "for AC" shaft assemblies and can get fuel IN at the front. Some appear to have 3 IN positions. Front, Back and End. Not sure if all INlets have threads. One I'm thinking just has a flat brass plug.

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Steve in NJ Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Andover, NJ Points: 11883	Post Options Post Reply Quote Steve in NJ Report Post Thanks(0) Quote Reply Posted: 07 Dec 2009 at 10:31pm
	Fuel inlet tap size for Zenith and Marvel carbs is 1/8th NPT. Some Zenith parts interchange providing they're from the same group or family of carbs. Check the P/N's on the riveted discs on the fuel bowls to I.D. what you have.... Steve@B&B

Ken in Texas Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Henderson, TX Points: 5919	Post Options Post Reply Quote Ken in Texas Report Post Thanks(0) Quote Reply Posted: 08 Dec 2009 at 7:11am
	Steve. The fuel inlet tap size I knew. Its the inlet Valve Seat Thread size I have a question about. I did take a valve seat to Fastenall yesterday after posting to get a matching tap. After about 30 minutes of trial and error, it was just as I figured. It is a special thread. There is only one tap and it must belong to Zenith Inc. Fastenall can get close but not spot on. Turns out only 2 common standard thread sizes are close , A metric 10 and a 3/8-24 both are loose fitting but snug up when the shoulder on the valve seat makes contact. I bought a new 3/8-24 bottom hole because it fit a little less loose than a M-10. I will let you know how it works out after I use it.

Steve in NJ Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Andover, NJ Points: 11883	Post Options Post Reply Quote Steve in NJ Report Post Thanks(0) Quote Reply Posted: 08 Dec 2009 at 10:19pm
	Ken, the thread size for the needle seat is also 1/8 NPT. Every once in a while I have to run a tap down that seat thread to straighten the threads out in customer's carbs... Steve@B&B

Ken in Texas Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Henderson, TX Points: 5919	Post Options Post Reply Quote Ken in Texas Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 9:19am
	Steve I beg to differ with you on the needle valve fuel inlet seat having the same size threads as the external fuel inlets to the carb and other external tapped openings. All you have to do is measure OR try to thread the valve seat into a !/8 NPT hole. The valve seat measures .348 across the threads. Thats about exactly the ID of a female I/8 NPT fitting. A 1/8 NPT male fitting measures across the threads .396. A Valve seat fits loose in a 1/8 NPT tapped hole without touching the sides. How do you logically manage to straighen up the valve seat threads with a 1/8 pipe tap when they are so obviously different? By the way the 3/8-24 tap worked OK and I could use the Zenith Core I had. A little loose threading in but the seat tightens up OK when the shoulder contacts the gasket. A little research and a clue or two from DickL on straight pipe threads for special applications still hasn't turned up the actual tap size for the valve seat threading. You being in the business of Carb restoration should be able to find out what special #tap correctly matches the valve seat threads.

Dick L Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Edon Ohio Points: 5087	Post Options Post Reply Quote Dick L Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 10:28am
	It is a straight thread. I had a tap that I used on several carburetors a coupla years ago but this summer I could not find it. My orderly part and tool filing system using used ground meat pans and discarded boxes of all sizes from very small to kinda large setting almost anywhere on the property lacks a little desire. I do remember that I originally found the tap in a box that was a flee market find and , and I could not find a size etched anywhere on the tap shank. I (assumed) at the time that it must have been a straight pipe thread because none of the taps in any of my sets fit those threads. Assumptions can get you as much trouble as buts as most know. With only having one arm at this time to move stuff along with it being a bit cold will delay for a spell my digging thru a bunches of pans and boxes that might by chance hold the treasured tap.

Ken in Texas Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Henderson, TX Points: 5919	Post Options Post Reply Quote Ken in Texas Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 12:20pm
	DickL I looked up "Treasured Tap" in all the Catalogs I have and on several internet sites. No such animal listed. lol I'm sure glad I didn't use a 1/8 NPT pipe thread tap like Steve uses to straighten up those treasured tap threads. I would need to have used JB weld to hold the seat in. Lesson Learned Don't ever assume anything from all the answers you get to Questions on the forum.

skipwetle NWIA Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 14 Sep 2009 Location: Danbury, IA Points: 94	Post Options Post Reply Quote skipwetle NWIA Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 1:38pm
	Im not an expert, but it could be British Standard Pipe thread, BSP, which is a straight thread, not tapered like American pipe, but the same thread pitch. HTH

Skyhighballoon(MO) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Pilot Grove, MO Points: 3115	Post Options Post Reply Quote Skyhighballoon(MO) Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 3:23pm
	Ken - I don't see anywhere where you gave Steve the model number for the specific Zenith carb you were working on. He asked you for the carb ID and later gave you a generic answer without the benefit of the model info. While it's possible Steve made a mistake or typo, I'm sure his answer is accurate for many other carbs, obviously just not yours. Steve gives out lots of FREE expect advice on carbs & electrical on this forum. I can certainly understand your frustration in having an oddball problem but dinging people who are trying to help is going to turn people off to wanting to answer questions. Just my 2 cents. Mike
	1981 Gleaner F2 Corn Plus w 13' flex 1968 Gleaner EIII w 10' & 330 1969 180 gas 1965 D17 S-IV gas 1963 D17 S-III gas 1956 WD45 gas NF PS 1956 All-Crop 66 Big Bin 303 wire baler, 716H, 712H mowers

Ken in Texas Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Henderson, TX Points: 5919	Post Options Post Reply Quote Ken in Texas Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 4:14pm
	Just for the record Mr. Sky. I'm not dinging anybody. But I'm feeling a little dinged for being accused of dinging All B/C/CA Zenith carbs be it a 206989 or a 224641 or #s in between use the same float valve assembly. Needle and brass seat with gasket. It's just as simple and as generic as that. Nothing oddball about the subject of what we are discussing here. It's exactly like I said. A new brass seat will not catch any threads in a 1/8 NPT threaded hole. That tells me it is not 1/8 NPT thread. What it is--is the answer we are looking for. I'm sure Steve has checked again and will post a followup.

Steve in NJ Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Andover, NJ Points: 11883	Post Options Post Reply Quote Steve in NJ Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 6:20pm
	Hi guys! It took me a while to get back on the forum here, but been busy at work with the weather Mother Nature is dealing us. When you work for a utility, things can get a little crazy. Whew! Ken, I apologize if you felt that you were misled on the thread size, but as I said, that's what I use to straighten or remove heavy rust from the seat threads both on the Marvel as well as the Zeniths. An 1/8-27 tap is what I believe it is. Haven't had a problem where a seat was loose, and I've done a couple of those Zenith carbs over the years. I don't know, can't explain it. Maybe my tap is worn? On the carbs that don't have a lot of rust in the threaded area, I use a tiny wire brush in the end of my portable hand drill to run in and walk out a few times. Gets the threads nice n' clean. That same brush I use in the inlet port also. Works great for removing that trapped rust, pipe tape, and debris in the threads and at the back of the inlet. There very well could be a special straight line tap for those particular threads as you and Dick L presume, but the tap I have seems to work fine for getting things straighten out or cleaned... Sorry, just trying to help ya out there..... Steve@B&B

LouSWPA Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 11 Sep 2009 Location: Clinton, Pa Points: 24345	Post Options Post Reply Quote LouSWPA Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 7:18pm
	Hey Dick, what happened to your arm? Hope it's not serious.

Ken in Texas Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Henderson, TX Points: 5919	Post Options Post Reply Quote Ken in Texas Report Post Thanks(0) Quote Reply Posted: 09 Dec 2009 at 9:02pm
	Steve@B&B Next time you rebuild a B/C Zenith please remember this thread cause its all about threads. Thread a valve seat into a nice clean 1/8 NPT threaded hole and give us a honest report. No need to try to thread a 1/8 NPT pipe thread fitting where the valve seat goes. I don't want you to mess up any threads. Oh. After that explain to DickL and I what the meaning of Presumptuous is. We certainly don't want to be the O'Reilly word for the day, "Presumptuous" Like I said above. I solved the crappy seat thread situation with a 3/8"-NF 24Thread bottom tap. But that still don't make it the right tap for the job and I would discourage others from doing as I did just because it worked for me. I thank you for trying to help a fella out. A guy with your excellent connections can probably solve the valve seat thread dilemma and come up with a size thread cut by what DickL calls a treasured tap. Be carefull out there. Mother Nature and her weather can be cruel at times. K in TX

Steve in NJ Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Andover, NJ Points: 11883	Post Options Post Reply Quote Steve in NJ Report Post Thanks(0) Quote Reply Posted: 10 Dec 2009 at 5:38am
	Ken, That's somethin' to look into, and when I git' a few moments, (holidays are comin' up) I'm going to look through a lot of the information that I have gathered on these carbs and see if I can find some info on the correct thread size for that seat. I never chased after it (no pun intended) because what I've been using seemed to work fine to me and assumed what I was using was correct . (my Mother always said never assume) This is the first I've read on this subject. If I do find a special thread size, I will definately post it here on the forum for everyone. This way we all know what it is! lol! Glad to hear you did find a remedy for a fix.... Steve@B&B

Ken in Texas Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Henderson, TX Points: 5919	Post Options Post Reply Quote Ken in Texas Report Post Thanks(0) Quote Reply Posted: 10 Dec 2009 at 8:20am
	Thanks Steve I'm Gone Trout Fishin. Wish me Luck. It ain't every day you can do this in NE TX. I can smell that apple wood smoke already and haven't caught any yet.

Steve in NJ Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Andover, NJ Points: 11883	Post Options Post Reply Quote Steve in NJ Report Post Thanks(0) Quote Reply Posted: 10 Dec 2009 at 9:37pm
	Good Luck Ken!! Catch a lunker!! Steve@B&B