Thread: zenith carb

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  1. #1 zenith carb 
    Spitfire
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    I have a 1980 tr7 us triumph that seems to be flooding out. do I need to put oil in carbs if so howmuch and what kind
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  2. #2  
    Brit
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    There is a special damper oil that was (maybe still is) sold in a small plastic bottle labelled as Zenith carb damper oil. I don't think anyone here will tell you that is critically important. (I think Victoria British sold it...)

    What most of us have done with Zenith Stromberg or even SU carbs, is to use a normal engine oil. Does the viscosity really matter? Probably not, although I do recall reading somewhere about using something similar to what you would put in the engine. So a lighter weight oil for colder/winter months and a heavier one for summer. Most of us don't get out in really cold weather so perhaps a 10W30 or heavier should work.

    How much is enough? The damper that raises and falls inside the carb cover has a reservoir tube. You should fill this with oil to something like 1/2" below the top of the tube. You don't want it to overflow when the screw-in piston is inserted.
    1979 Triumph TR8 Coupe
    1981 Triumph TR8 Convertible
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  3. #3  
    Hi Clay,

    What you say "flooding out", what do you mean? Fuel coming out of the float chambers? Too much fuel going into the engine?

    The advice on what oil to use is right on, but the only affect that has is to dampen the movement of the needle in the jet, and mostly affects the mixture during transitions of the throttle setting.

    Welcome!

    -Darrell
    ---------------------------------
    Darrell Walker
    66 TR4A IRS-SC CTC67956L
    81 TR8 SATPZ458XBA406206
    Vancouver, WA, USA
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  4. #4  
    Brit
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    Darrell is correct that I did not address the flooding problem. That is next of course, to find out WHY. Has the car been sitting for a long time, could the jets in the carb floats be stuck open? Has the fuel pump been changed to something with too high a pressure?

    I guess we need some more background, anything you can tell us that might lead us to the problem or solution.

    David
    1979 Triumph TR8 Coupe
    1981 Triumph TR8 Convertible
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  5. #5 zenith carbs 
    Spitfire
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    i have had the car a few years and never put oil in the carbs. the reason I think its flooding out is because at times it runs really rough and I get black soot out the tailpipe. I think it has a FASD type choke, are there a way to check it, also are there a way to disable it? Thanks for the reply
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  6. #6  
    Brit
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    The oil in the damper helps to "dampen" the lift and fall of the piston with changing air flow. Also, it helps to provide a little extra fuel/richness when you initially crack open the throttle. The oil in there is important.

    As for the FASD, it is not easy to disable, and in fact diagnosis/repair of this device has been recently been a topic of the Triumph Wedge Club, the TWOA. If you are not aware of them, get some info and contacts at http://www.triumphwedgeowners.org

    It is important that you have good water flow through the water passages of the FASD, so also make sure your coolant thermostat is working, and the correct type and temperature. The TR7 does use a bit of a weird thermostat, so beware if you have replaced it.
    1979 Triumph TR8 Coupe
    1981 Triumph TR8 Convertible
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  7. #7  
    Young Brit
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    In my TR6 triple carbs, I use either 3 in 1 oil or Marvel Mystery Oil, each of which is readily available at a FLAPS or good hardware store. The 3 in 1 is easy to add with the long skinny snout that you can allow to drip in slowly to get the level to the proper height.
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  8. #8  
    Spitfire
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    If you have never added oil to the carbs...this tells me the carbs are most likely in need of rebuilding. If the float is stuck open...this might be due to dirt or rust in the fuel line...or the gas tank. Do you have a fuel filter on your car? Is it clean? How is the rest of the car running? When was the distributor last rebuilt? Are there any vacuume leaks? Is the car over heating? Before blaming the FASD or trying to fix the FASD...everything else needs to be in good order.
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  9. #9  
    Spitfire
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    The only way a Stromberg can "flood" is if the float valve is stuck open or the float sank. Fuel will then be forced up the jet and vent pipe. Disconnect both vent pipes to see if fuel pours out of one or both. The FASD will not cause a car to run rough. If it's stuck "off" it will make starting hard or practically impossible. If it's stuck "on", the idle will be too high and the mixture a bit rich and you will note that air will be drawn into the FASD even after the car has reached operating temperature. It is critical that the water jacket at the FASD is bled of any air bubbles as this will prevent the thermostat from getting warm enough to close the device. An engine with a head gasket leak will put air bubbles in the coolant and will dry out the FASD's water jacket, preventing it from shutting off. If you have a head gasket leak, don't blame the FASD.

    But as I said, the FASD will not cause a car to run rough, only fast. Check the diaphragms for cracks, holes and splits. These can cause rough running.
    Last edited by wmsimpson; 03-25-2012 at 04:24 PM.
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  10. #10 Dashpot Oil 
    Spitfire
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    Oh, the ROM recommends 20W-50 engine oil in the dashpots. Been using this for many years.
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