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Old 03-21-2004, 09:50 AM
BB427 BB427 is offline
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Join Date: May 2003
Location: Newburgh, IN, IN
Cobra Make, Engine: 427SC Unique
Posts: 481
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Matt,

I questioned Mike @ Pierce about the small jet holder and he informed me that this is the way they overcome the 2500 to 2700 rpm "pop" or "lag" associated with Webers. We had a great discussion about the fuel today compared to the heavy fuel from 30 to 40 years ago. Todays fuel is so much lighter that it takes 1.2 times as much to achieve the same result. Todays fuel injection with 60-160lbs of fuel pressure works well with this fuel but a 40 year old carburator won't without some changes.
To make a long story short, I left the 60 jet holder and dropped to a 50 idle jet . My idle screws are all between 1-1/4 and 1-1/2 turns and it runs great. It starts easily cold, shuts off quickly, and starts as easily hot as it does cold. The road manners are great and Mike was right ,I have no issues with the transition between the idle circuit and the main circuit. The factory 120 holder changes the entire fuel curve and it acts rough at 2700 rpm and does not really clear up until after 3000 rpm.

Webers ROCK!!!!!

Thanks for asking!!

Brent
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