• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

ZS Manual Choke

Share this page

Morris

Morris

Yoda
Offline
Hello all,

I am attempting to adapt a manual choke from an earier ZS carb to my water choke carb. The car fires and idles like never before, but it will not run faster then 30-40 miles an hour. Does anyone have experience with such a project who can lend a bit of wisdom?

I am working on a fuel injection retrofit for this car, so I am loathe to spend any more money on the carb. I only want to be able to enjoy driving about in the forthcoming fall weather until my FI system is ready.

Thanks,

Morris
 
Okay, so I read Rick Jaskowiak's incredibly wonderful article on the water choke and confirmed that everything on my water choke is working as it should. I put the water choke back on and still, the car tops out at about 30-40 miles an hour.

My next project is to invent a time machine, travel into the past, and make sure that Mr. Zenith and Mr. Stromberg never meet.

Then maybe I will rebuild this stupid carb.
 
Did you take the carb off while working on this? Try checking to make sure the throttle cable didn't slip so that throttle disc is opening all the way. I am just taking a guess at this one. I never could figure out why the water choke never worked on my 1978 and finally ended up getting a deal on a manifold and HIF-6 someone had laying around. Worked OK but I had to experiment a lot with needles, etc. I finally went to the dual setup of HS4's the British had on the 1500. Really sweet!

Let me know if you figure this one out as I am interested. Good luck
 
Let me ask a couple of basic questions. Did you make sure that the diaphragm on the top isn't torn? A torn diaphragm will act that way. Also, they say if you run out of dampener oil in the top of the carb it will make very little power as well but I don't think it is as drastic as a torn diaphragm. Those are the places I would look first and it is an easy check. Let us know what you find.
JC
 
Thanks for the feedback. I did check the diaphram and found no rips. I even replaced the diaphram with my back up phram to be sure, but still, it chokes out at about 30-40. As far as I can tell, the throttle linkage is functioning as it should.

It feels like the car is leaning out. It will be cruising along fine, hit a certain speed, then power completely dies off. I let off the gas, then hit it again and the car comes back up to speed, then promptly dies off again.

Would an incorrect float level cause this kind of behaviour? I did replace the float and valve at the same time that I put the manual choke on. Could this be the source of my grief?

Thanks,

Morris
 
It could be a source of your problem but it doesn't seem very likely. It is easy to check the float level so for the peace of mind that it gives I would go ahead and verify it. If it is starving for fuel, you might check the output of your fuel pump. I've heard of similar symptoms where the fuel pump couldn't keep the float bowl full at speed. Another thing to check is the suction tubing to the pump. If it is sucking air in while it is running the capacity will be greatly reduced. The suction piping might not be leaking when the pump is not running but air can still eek it's way into the system. This is just a thought though. I'm assuming when you put the new diaphragm in the carb you checked the operation of the air ram. Also I think there are vent holes between the body and the cap that you have to be mindful of when reassembling it. That isn't likely if you didn't take the diaphragm out until after this started happening. Anyway, check the fuel pump output, make sure no rust or junk is getting up to the carb from a rusty tank (common, check the float level again, make sure your air filter isn't clogged, pull the air filter housing and have someone operate the throttle so you can watch the butterfly.
Let us know what you find out.
JC
 
Oh and one other thing I forgot. Check and make sure you aren't drawing a vacuum on the gas tank. If this happens it will starve the engine in a similar manner. The emissions control system is notorious for stopping up and causing vehicles to run lean. An easy check would be to disconnect the tank vent vapor canister or you could make a run with the gas cap loose.
JC
 
Thanks for all the great feedback. It will probably be Monday before I can try this stuff. The folks are in town to visit the new(ish) grand child. I will let you know how it goes.

morris
 
Back
Top