[T3] Loss of power at speed- could it be overheating- update

[Jim Adney]

On 31 Oct 2010 at 23:15, Mark Seaton wrote:

> The float was free to move but didn't seem to move 
> down very far before bottoming on the main jet housing in the bottom of 
> the bowl. I removed the float and noticed something I had seen but never 
> really thought about before, but this time it all added up- there was a 
> flaw in the casting of the carb body resulting in a small raised worm 
> like "flashing" on the top of the main jet housing. It probably sits 0.5 
> - 1mm above the surface, directly where the float would hit. 

I'm not a carb guy, so I surprised to hear that things are so tight 
in there, but very little motion of the float is actually needed. 
Looking at your photo, this casting flaw looks pretty trivial, but 
you're right that the float needs its full range of motion.  

One thing you could check would be to blow thru the gas inlet with 
the carb rightside up and upside down (with the right washer), with 
the carb assembled, but off the car. Then remove the casting flaw and 
repeat the test. That would give you a better idea of whether this 
really cured something.  

> I just removed the fibre washer from under the needle valve to raise
> it a little and put the carb back together. I drove off and just got
> back home with no further issues. In fact it drives smoother and more
> assuredly than ever. 

Removing the washer was a really clever way to deal with this 
temporarily!

It would be great if this was it. If these are OE carbs, the washer 
thickness is one of the specs in the OE setup data. You can check 
this to make sure you have the right spacing in there. Varying the 
washer thickness adjusts the depth of the fuel in the bowl, so it 
amounts to a fine adjustment on richness/leanness. It would be 
important to make sure you end up with the same thicknesses on both 
carbs.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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