John Maddison’s Blog…

Cobra Master and more…

How to calculate correct carb size…

Here’s a formula for working out the correct size of carb for your motor:

395cu/2 =197.5
197.5 x 3.47 =685 cfm assuming 100% efficiency,but take it you did a good job on cams head exhaust etc we will use 80%

685 x 0.8 =548 cfm

Just substitute your engine size in cu” and your redline max revs in the above formula.
So if your carb is jetted and set right a 600 cfm will be perfect.Here’s a link for you to find the correct carb size for your motor.

Good luck.

 PS. It does not help to overcarb your motor!


June 29, 2007 - Posted by | Uncategorized

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