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  Feb. 1, 2009 5:31 p.m. theshopeac None

  In the recent issue that had the head porting article on an MGB head, you had a chart showing that the B engine would have to rev at 10K rpm before it needed bigger carbs. How is that calculated? I am doing the engine work on my Corvair project, and I suspect that it is under carbed for the displacement. It is 2.7 liters, and has 2 1 1/4" carbs. Before I waste a bunch of time fabbing up a bigger system, I would like to be able to work out how big they need to be. Thanks, both for the original article, and the help, Jesse in Rockville

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  Feb. 3, 2009 8:05 a.m. Carl Heideman

  The basic formula for this is: carb cfm = rpm x displacement / 3456 x VE. VE is Volumetric Efficiency. Figure about 75-80% for a stock engine, higher as the engine is properly modified.
  

  There are quite a few online CFM calculators out there. Here's a link to one: http://www.wallaceracing.com/intakecfm.php

  --Carl

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