British made Zenith vn carburetor

I have a british made Zenith vn carb. on my 3414 international tractor that puts gas into the crankcase oil. I understand this is a trademark of these carbs. I have gone through the carb, float set ok, plugs are all ok. I have installed a electronic ignition and have good spark to plugs. The timing is set 10 degrees advance, is this correct. The engine seems to run to rich but can not lean it down. Could the jets be down sized in the carb? Need help as I have run out of ideas.

Air cleaner good and clean if not that can cause that type of problem

Leakaage a "trademark" of the carbs? I never heard anything like that. I've got two tractors with VN carbs and one with the VNN. All fairly simple down-draft 30mm British-Zenith (more-or-less Solex) carbs.
Never had any issues with any of them that differ from any other automotive carb. They differ a bit from many carbs used on tractors because they have accelerator pumps/power valves (VN,not the VNN) and the same carbs used on IH 3414s were also used on several cars. I don't know what is wrong with your carb but it certainly isn't something typical or a design flaw. If a VN it ought to be a 3063945R91. If a VNN it should be a 3044193R92. If you are sure the gaskets are good, float OK and needle and seat good - maybe you need to check the main jet and make sure someone didn't change it or drilled it out.

I've got the British Zenith VN and VNN repair manual here if you need any info. The 30 mm VNN was also used on 1963-65 Commer Cob series III with 1390 cc engine, and the 1963-65 Hillman Husky series III with the 1390 engine and 1961-1968 IH tractors with 2360 cc engines. THe 30 mm VN carb was used on the 1960-61 Hillman Minx, 1963-65 Singer Gazelle Mark V.

Also a few similar carbs used on old Jeeps and VWs.

does the tractor have the correct fuel pump on it?

thanks for the enfo on the carb, mine is the vn
I am going to go though it again to make sure its right. I'll also check the main jet. The tractor is around 45 yrs. old and I have rebuilt or replaced a lot of parts on it. Maybe you could tell me how to get good brakes as they are not to good. I have replaced the disks and that helped some. Thanks again.

It has a replacement pump from Bates International on it now. It is the second time I have replaced it. I have a in line pressure regulator that I use with it set at 2 lbs. I replaced it thinking it was the problem but it acts the same with the new one I put on last april.

good and clean. I tried it without the aircleaner on and still gained the gas in oil.

Does it have a fuel pump on the side of the engine?? If it dose the fuel pump maybe bad and leaking gas into the oil

(quoted from post at 03:38:53 10/24/13) thanks for the enfo on the carb, mine is the vn
I am going to go though it again to make sure its right. I'll also check the main jet. The tractor is around 45 yrs. old and I have rebuilt or replaced a lot of parts on it. Maybe you could tell me how to get good brakes as they are not to good. I have replaced the disks and that helped some. Thanks again.

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The brakes kinda suck even when everything is right on those tractors. Do seal around the covers when you put them back on with silicone or somesuch. Otherwise oil and or water can get in and degrade their performance.

(quoted from post at 05:30:13 10/24/13) Does it have a fuel pump on the side of the engine?? If it dose the fuel pump maybe bad and leaking gas into the oil

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they have an external electric fuel pump that kinda clicks instead of whirs. Not sure how it works a solenoid pump?

I replaced it thinking this could be the problem but it didn't solve the problem. Is there a way to check the pump for a leaking diaphragm? If it is leaking its straight in to the oil. The pump is not very old but I suppose it could of had a pin hole in it. I could take the one I replaced apart and see if the diaphragm looks ok.

The way things are made now days you may have gotten a new bad fuel pump and they are not easy to figure out if they leak or not and you a lot of times can not see a pin hole in the diaphragm

(quoted from post at 19:16:38 10/24/13) I replaced it thinking this could be the problem but it didn't solve the problem. Is there a way to check the pump for a leaking diaphragm? If it is leaking its straight in to the oil. The pump is not very old but I suppose it could of had a pin hole in it. I could take the one I replaced apart and see if the diaphragm looks ok.

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Is it an electric pump mounted on a bracket?
That is what most of the British designed Internationals used.

It is mechanical.

Searching for info on zenith VN carb. Mine has a stuck piston pump. Any ideas on freeing it up? soaking in carb. cleaner presently but has not freed up yet.Other solutions out there ?
Am also looking for rebuild kit. i noticed you mentioned you had a manual for the VN. Any way to pass that on ?

Regards,
IH3444

I put the fuel pump that I had replaced back on and ran a return line after the pump back to the line going into the pump. I didn't run the return line back into the gas tank because I would have to drill a hole ect. to get it in. This bypass seems to be working ok and seems to have solved the problem of the gas going into the oil. The fuel pump probably had a hole in it like you suggested. The carb still is rich but the tractor runs the best it has for years. Thanks

(quoted from post at 16:27:40 10/25/13) Searching for info on zenith VN carb. Mine has a stuck piston pump. Any ideas on freeing it up? soaking in carb. cleaner presently but has not freed up yet.Other solutions out there ?
Am also looking for rebuild kit. i noticed you mentioned you had a manual for the VN. Any way to pass that on ?

Regards,
IH3444

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I am having the same problem how did you get your stuck piston out? did anyone have any ideas or solutions