Zenith Carb problems

[Tajman]

Having been able at last to get my Haflinger on the road legally, got my new logbook and date related registration from DVLA after 6 weeks. I did a 4 mile drive around the blocks to see how things went after rebuild. Mostly ok. After the 3rd mile the engine started to miss. I managed to get home. I decided that it was a carb issue. That evening I went onto the forum and found some good information in previous posts . 2014 .
I decide to borrow a compression gauge and check the cylinders before any other work. Both came out at around 118 PSI. So I was pleased with that and could presume it was not a valve issue. When I took the plugs out they were both very black sooty. Obviously running rich. I sort of thought with the engine running in the garage, although not that smokey, that it smelt a bit rich. Anyway, with more research and a read of Ron Ladow literature, I decided to strip the carb down again. There is a lot of info out there , including You Tube stuff about the Zenith32 Ndix, but mainly to do with the fact they were also fitted to early Porsche.
When I got to the part where I took out the valve under the accelerator pump, I was a little confused. See pictures. I can not find anywhere a decent picture or parts list of what is supposed to be there. There is the main brass screw in casing.There is a smaller screw in part. there seems to be a rubber o ring on that. There is a small "flap" of material that sits inside the main screw and there is a rubber o ring that fits in the recess of the bottom of the larger screw.Is this supposed to seal with the bottom of the plunger/pump? At present it is inside the recess so would not touch the plunger pump.
Anybody got any pictures of what should be there? Thanks in anticipation. Jeff.

[AustHaflinger]

I cannot help with your specific question however I had a long run of carb issues and it was only when I bought a full rebuild kit and put it in that problems resolved. I sourced mine from a local carb parts seller here in Aust.

Be aware that the Porsche carb is slightly different to the Haflinger Carb - as such the main components are the same but many of the secondary parts may be different so be cautious. Mercedes cars, Pinzguar and some Unimogs use the same carb - my carb is a mix of Unimog and a Haflinger valve block.

So my advice - is get the most comprehensive rebuild kit you can find and put it in.

Garry

[heinkeljb]

Your pictures look the same as the items in Lurch, so I would presume them to be correct. The ring that is on the top of the Jet as shown in your last picture obviously is design to seal the joint between the jet and the top of the hole it goes into. I believe the little "bakerlitle" (I think that is what it is made of) disc obviously works as a one way valve to ensure there is always some petrol above it for when you put your foot down and the piston squirts neat petrol on to the carb to counteract the sudden "leaning" of the petrol air mixture being drawn into the engine.

I find that usually when my engine starts misfiring, it is because there is something blocking the one or other or both the idle or main jets found under the little cover on the side of the Carb. Take them out one at a time and blow air through them in the reverse directions. Not really a good idea to stick anything down the holes to clear them as you might scratch the inner surfaces which would change the value of the jet.

If you can replace them in your carb it might be a good idea as petrol flow through them over how ever many years they have been in there and how ever much petrol has passed through them, they could be worn - think Grand Canyon on a smaller scale - Water has made a very deep canyon....

John

[Tajman]

Thanks, As Gary said, I should have got the complete rebuild kit with all inside including the Accelerater plunger etc. It seems I only got the basic gasket, seals and washers kit. So I will endeavour to get the other bits and may consider the jet replacement. I broke the adjustable pump rod, trying to free it off so that I could alter the length if need be. So I have to replace that.
I did not have any "miss" firing. It seemed more like the engine was getting choked up. A few days later with a restart to warm it up before the compression test, it ran ok again. Anyway I decided by then to strip the carb as the plugs were so sooty, so that's where I'm at now. So bits to order and tomorrow I am off to the welders to get the Hood frame /roll bar thingy welded up. I have prepared it and bent the tubes . I will post some photos when the frame is fitted.
Jeff

[ogdenenterprise]

Hi Tajman,
you mentioned you broke the adjustable rod, when you replace it set it up as I was advised to do in the last bit of the thread. I have copied this from one of my previous posts, carb return spring

My pump rod is in the end hole, I was told to put it in this position by Tony Hrleja . I was having problems with the carb so I sent it away to be rebuilt at a local carb repair shop. I sent it back a couple of times because it was not set up right. I eventually found out they were testing it on a six cylinder engine and the pump rod was set in the same position as yours. I contacted Tony in desperation., He told me to remove the rod and lift the top lever and when I just felt resistance this is the length the rod should be set at with the rod in the end position, hope this helps.

Dave

[jhon]

If your carb rebuild goes well but your plugs are still sooting up try fitting a pair of one range hotter spark plugs. I too had a plug sooting condition that would result in a misfire, in particular on one cylinder - this was cured with the hotter plugs.

Ditto what John said about the idle jets blocking up - they are prone to doing that - fitting a further in-line filter helps with that also.

[Tajman]

Thanks for the comments,
I think it was Dave /Ogdenenterprise that posted a picture in a 2014 post of the pump valve and its sealing rubber. I do not have that rubber fitted so I am sure that is my rich running problem. Dale at Haflinger Technix also clarified that, unfortunately he has no stock of that item.
So I will search around the Zenith carb spares suppliers. I attached that photo from Dave. Thanks.

[Goatwerks]

You can use the newer type pump check valve from a Unimog 404 or a Pinzgauer.
I rebuild many Zeniths.
The 32 has many interchangeable parts.
You can also use the Mog pump plunger with viton rubber seal if you adjust the pump rod to 73mm on center.