John Maddison’s Blog…

Cobra Master and more…


I have been working on and building cars for as long as I can remember. It started when I was around 6, working in the garage, helping my dad. By 1986 I built my first Cobra (and had one parked in the garage ever since). Today I work on Cobras and am also a licensed Carroll Shelby distributor selling clothing tailored to the Cobra and Shelby markets. I encourage you to visit my other site, Slither Clothing.

After helping a countless number of people sort issues on their Cobra’s and other types of cars, I figured that I wanted to start sharing some of the knowledge that I have accumulated over the years. I hope that this can help you with an issue that you may be having. 

If you would like me to answer any specific question(s), please feel free to ask.

Thanks for stopping by!



  1. I have noticed a lot of interest in Carb sizing and jetting info.Firstly the biggest mistake we make is to put too big a carb on the motor and then try to adjust it to run right.Hers a formula for working out the correct size carb.
    Try this,
    There is a formula that will get you very close to the proper cfm for your engine. The formula goes like this:

    cubic displacement divided by 2 (ex: 351=175.5)

    maximum rpm divided by 1728 (ex: 6000 rpm=3.47)

    multiply those two figuires (ex: 175.5 x 3.47=608.98 cfm)

    Hold on we are not done. You now have to factor in volumetric efficiency. A Nascar race engine runs at 85%-90% volumetric efficiency. A normal street car wil be 75-80%, depending on what you have done with your heads and exhaust.

    Ex: 608.98 x 75%=456.74cfm

    Comment by slitherclothing | June 27, 2007 | Reply

  2. Hey ,Who would be interested in having originality or other pertanent Cobra questions answred by Carroll Shelby Himself? Leave feedback on the site.

    Comment by slitherclothing | June 27, 2007 | Reply

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