Bookmark This Page


Getting Started

Engine Tech
Shop Math
Tech Specs
  Value Guide  

   Classified Ads

Contact Us
Terms of Use


 Classic Truck Shop Garage
 Quick & Dirty Carburetor Sizing

his is a real quick and dirty formula for figuring carburetor CFM requirements for a street engine. This "Ballpark"  method is very useful at the swap meet, parts store, or when impressing friends and family.

Take the engine displacement and multiply by 2.  Then subtract 15% from the total.  For a little healthier engine, subtract only 5%. 

This a real ball park formula.  For a more accurate calculation, see the  Carburetor Sizing Calculator.  But, this is still a good formula for general sizing purposes.

d = Displacement in Cubic Inches.           (d x 2) - 15% = CFM

EXAMPLE: d = 350       (350 X 2) = 700    (700 - 15%) = 595 CFM