View Full Version : TR6 Carb leaking

03-13-2014, 05:16 PM
I just rebuild my carbs and reinstall them. After running them for the first few minutes the front carb started leaking out of a breather hole(top left corner) on the air cleaner side. It was also leaking around the gasket around the float chamber. Why is this leaking? Are the screws not tight on the float chamber? Can anyone help me out. Thank you. Attached is a pic of the hole that is leaking. I don't know why the picture is sorry so I'm sorry about that.

03-13-2014, 05:28 PM
Your carb's float valve is not closing either because it is defective, not set properly, or you have a leaking float. Sitting still and idling the fuel should never get up high enough to get the float bowl gasket wet. If you have installed an aftermarket fuel pump that delivers too much pressure you can also see this problem. Ideally would like to see no more than 2 to 3 PSI fuel pressure at the carbs.

If you have installed a Grose Jet, remove it and clean it thoroughly with spray carb cleaner. I have been told that they ship with a Cosmoline like coating on the steel balls to prevent them from rusting while in storage. The coating has been known to keep the valve both from closing and from opening. I prefer using float valves with Viton tips and have removed the Grose Jets from my cars.

To test the float, remove it from the carb and place it in a shallow pan or jar filled with gas. Both pontoons should be pointing "up". If the float completely sinks or only one side floats, replace it. Many vendors now carry Stromberg floats that are made of a material more compatible with modern fuels and described as unsinkable.

Bend the float arms as necessary to insure the float valve height is as specified in your service manual.

03-13-2014, 05:30 PM
The needle valve inside the carb is not shutting off properly - it could be stuck or perhaps the float is not adjusted properly. I think you'll probably need to pull the carb again and open up the float chamber again to check things out. The gasket leaking is a separate issue but is probably worsened because the fuel level is too high in the float chamber.

edit: What Doug said, faster and better than me!

Geo Hahn
03-13-2014, 05:42 PM
...Many vendors now carry Stromberg floats that are made of a material more compatible with modern fuels and described as unsinkable.

Sold under the brand name 'Titanic'?

The originals can fill with fuel and but my money would be on there being stuck valve -- even a new one can hang up a bit.

03-13-2014, 06:54 PM
Another possibility is that the fuel pressure is too high for some reason. Not likely if you haven't messed with the fuel pump recently, but even some new pumps put out too much.

Yet another possibility (and probably the most common in my experience) is that a piece of crud has found it's way into the valve and gotten caught there. If so, I would replace all the soft fuel lines as a precautionary measure. They don't last forever anyway, and the original lines will not stand up to modern fuel.

I've forgotten, did the ZS carbs come originally with the foam floats (aka Nitrophyl) ? They can be especially tricky, since the float may look and feel fine, but have absorbed just enough fuel to not be able to hold the valve closed under all conditions. I once spent a very frustrating week of vacation, fighting with floats that would only sink while going uphill (in my motorhome, not ZS carbs but Nitrophyl floats). The replacements lasted about 3 days and did the same thing!

Geo Hahn
03-13-2014, 07:28 PM
...I've forgotten, did the ZS carbs come originally with the foam floats (aka Nitrophyl)?

Mine are hollow -- you can tell if they have fuel in them by shaking & listening.

On my Jaguar I got one partially filled that would cause the engine to die on hard left-handers (otherwise ran fine). The engine felt like it was starving for fuel but in fact the submerged float was dumping so much fuel on left curves that the engine would stumble (the force of the turn would pull the slightly submerged float all the way down).

Those floats and valves can cause strange things to happen.

03-13-2014, 08:29 PM
If you used the needle valves that were in your kit or you bought Grose Jets, I'd suggest putting your old ones back in if you still have them.

03-14-2014, 12:12 PM
Geo the left hand turn thing is what kind of started all these issues. Stupid!!! Weird symptom.

I replace the needle valve with one out of the old carb and I'm still have having the issue. Just not as much fuel this time. Once I rev the motor no more leaking. I guess this leaves me with not having the floats adjusted right. I made sure the float was what the specs call for. Just to clarify I need to take this measurement by the float on both side closest to the pivot point? Thanks for the help

03-14-2014, 03:33 PM


03-14-2014, 05:19 PM
Try to get them the same level front to back
Also make sure you have the floats right side up...like the picture.

03-14-2014, 08:30 PM
Thanks everyone for the help. I got it fixed and my car runs pretty good now. Now I can enjoy the car since the weather is starting to break.

03-14-2014, 10:08 PM
You gonna tell us what you did ?

03-15-2014, 12:00 AM
I did magic!!! I raised the floats from around 5/8 to 3/4 and made sure the float touching the needle valve was flush.