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  #16  
Old 06-03-2008, 10:13 AM
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I got the uni-syn and carb hood adapters from baum tools, along with a proper valve adjuster wrench. Not cheap tho, and I heard the coolwhip method works fine.

The smoking is most likely due to oil control and has nothing to do with the carbs. UNLESS, and this is a big unless, it is black sooty smoke - similar to what a diesel would do. What color is the smoke? Blueish-gray is the bad stuff.

A sticking float valve could easily flood the heck out of the carbs at idle, create a black cloud of smoke and would do a number on your plugs and A/F ratio at the same time which would cause the rough running. At speed, the thing being stuck wouldn't matter as much. The ze-28k carb kits come with a new float valve and some different sized spacer washers to adjust the fuel level. If you are going cheap, try just buying a can of carb cleaner and really spraying the hell out of the float valves which you have already and work it in and out. Wear some rubber gloves first tho! You might want to do the same thing to the fuel return valve on the outside of the front carb - it unscrews with a big wrench. In my year this valve comes into play at idle and allows the fuel pump to circulate the gas around and keep it cool, later years just have a pinhole orifice to do the same thing. I could conceive of the fuel return not working possibly causing the pump to overload the float valve at idle (although that is just a theory that would need confirming)

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  #17  
Old 06-03-2008, 10:17 AM
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Skippy:

That is the tool you need. You will also need to buy or build a top adapter to allow the uni-syn to fit the carb top. You can get one from:

http://www.baumtools.com/

It is a bit flimsy and not like the original Zenith tool, but it does work. You can also make one from a cool whip can, but a tight seal may be a challenge.

Your smoke...the gas car or diesel? If gas, then guides may be the culprit...smoke a dense blue? Or is it black? Blue is oil (guides/rings), black is fuel (carbs/fuel pump pressure), white is water (head gasket).

Good luck with the LEOs.

230/8
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  #18  
Old 06-03-2008, 11:35 PM
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The smoke is gray to grayish white and smells like gasoline. There might be some oil component to it as well, since it's down a quart of oil already and I haven't driven it that much.

I tried to drive it to work this morning. I got two blocks and it stalled and would not restart. I didn't have time to mess with it, so I ran back to the house and grabbed a diesel. This afternoon, I took the tops of the carbs off again and found the float bowls dry (front) and almost dry (rear). I took the jet blocks out, removed the floats and blasted them with carb cleaner before reassembling. This got the car running again, but it's still idling rough, stalling, and smoking.

I went to check the ignition timing after I got it home, and found that my timing light isn't working. I verified that the secondaries are staying closed at idle. I also put my ear to each primary at idle and they sound like they are sucking the same amount of air.
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  #19  
Old 06-04-2008, 10:48 PM
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ZE28 kits ordered. The car has become basically undriveable, though I might still try to drive it to work tomorrow (free gas, and it's getting low). While I wait for the carb parts to arrive, I have plenty of cosmetic parts to put on.
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
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  #20  
Old 06-04-2008, 11:02 PM
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don't forget a new fuel filter. I recommend one with a replaceable element.
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  #21  
Old 06-05-2008, 09:21 AM
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One more thing - make sure your heat risers are open, especially in Nevada!

...and if you take apart the carbs to dip them in a cleaner bucket, I found that it is easier to just bend the tab slightly that actuates the choke pull-off in order to remove it, rather than remove the entire choke assembly and all the little swiss-watch type springs associated with it. After you remove the round choke covers/heaters, the choke pull-off is the little triangular lid held down by 3 screws with an adjuster screw in the middle. It has a rubber diaphragm and its function is to open the choke plate a little bit immediately after the car starts dead cold so that it doesn't load up with gas and run badly or stall in the first few seconds after starting. It's a nice little tuning feature to have, the replacement Webers I'm using now have a pull-off but it's either capped or not adjustable and they really need it because that's right when my car starts to struggle a little!
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Last edited by todds; 06-05-2008 at 09:34 AM.
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  #22  
Old 06-05-2008, 08:07 PM
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I was concerned about the heat risers when I read about them. Then I checked the car and found that they aren't present. There's a bracket on the exhaust manifold where I think that system used to start, but that's all that's left. Apparently a PO found carb heat unnecessary.
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
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  #23  
Old 06-05-2008, 11:02 PM
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To check the idle passages out count the exact number of turns to easily seat the idle needle. Then remove one to see how much flow is coming out. Do the same with the other carb.

If one is different than the other or no gas comes out you have obstructed idle passages with dried gas residue. This of course is provided there is fuel in the bowls. I have had obstructed idle passages and other areas of the carb affected by the dried gas residue several times.

My solution was to separate the gas line and rubber hose in the footwell area under the car. Run the engine till the carbs went dry. Insert the rubber hose in a quart or pint can of laquer thinner. Turn the engine over till it starts again on the laquer thinner. Then turn the engine off as the bowls are full of the laquer thinner. Pull an idle jet or both of them again. Watch to see if the flow increases. Takes maybe twenty minutes to dissolve the mess in there.

Yours I expect somewhat less. The concentrated laquer thinner dissolves the original dried gas residue and other junk that has accumulated over the years. It has worked for me when faced with knocking the carbs down otherwise and cleaning them plus kitting. The funny thing was the carbs worked better than the last time those engines ran well. So there was even pre existing varnish and dirt in them. Had to be.

The basic thrust here is you have nothing to loose if you expect to kit them anyways plus you know those passage ways are clear before removing the carbs if the cleaning does not do enough. I have never experienced the dreaded passage obstruction by oxidation of the base metals like some small carbs with zeniths.
The concentrated laquer thinner eats any residue and varnish very well. Plus the engine runs well on the thinner. My understanding is fresh gas will do it over a long period. Except I do no longer believe this as there was too much improvement with carbs in steady service back then.

Of course this approach will not fix defects in components. I was just amazed it does as much as it does. It really worked well enough for me to always try it again first if I felt the need. Stuff in the tank is so dilluted it has little real power to dissolve the varnish well. Just my opinion.
If you try it report back. This should almost be a periodic tuneup item on the old zeniths.
During all the posts there seemed no discussion about the prevalance of air leaks. This setup just loves to develop them in my opinion. A can of wd-40 sprayed around the base of the carbs will pick any up. Anothern clue you have them is the idle needle screw count. I have seen one idle needle at say two turns out and the other carb needle at ten turns out. Solid indication there is something way out of whack.
The only way to properly store these cars is to fill the carbs with light oil. It generally will not evaporate leaving a mess behind.
It is also quite typical with these engines to have worn valve guides and valve guide seals. To verify just have someone follow you. When you come off the gas and the car smokes a lot. You have that problem as well. Easy test that validates it pretty well.


Last edited by barry123400; 06-05-2008 at 11:16 PM.
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