<VV> Fw: Modified carbs performance question

[Michael Kovacs]

  Grant, 
 The only modification I've done to my carbs is to to remove the casting step between the upper and lower part of the casting. You can check the step with your finger by just feeling it from the venturi side. Usually the venturi and the throttle bore are offset a bit by cheap casting practices. 

 I just use a round  fine grinding stone in a drill to carefully to clean up the two mismatched castings. I follow up with a brake cylinder hone for a smother flow. In my '69 Nova it improved highway gas mileage by 2 mpg. 

 I have heard that the ventuti bore diameter can be opened up approx .015''. 50 years ago I had a friend open up the carbs on my '65 95hp .010'' It made a surprising difference in acceleration and gas mileage. Car long gone now.

    On Sunday, August 25, 2019, 2:38:29 PM EDT, Grant Young via VirtualVairs <virtualvairs at corvair.org> wrote:  
 
 I received a modified set of 140 carbs for rebuild that a customer purchased from another owner. They have been modified by increasing the venturi area to the same size as the throttle body area. The venturi cluster arms have not been extended. The other mods can be undone. But, before I spend time and charge for rebuilds that might not work as expected, I thought it best to check with those of you who have some experience with this. I have read that the step between the venturi and throttle body area is there to accelerate the flow and that cluster arms should be extended to allow them to operate properly and that idle quality and performance can otherwise suffer. 
Thanks for some insight.
Grant __



    
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