View single post by Greg Fletcher
 Posted: 09-21-2012 05:57 pm
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Greg Fletcher

Joined: 03-11-2005
Location: Lake Nacimiento, California USA
Posts: 425
Webers are not the hot ticket IMHO on the Lotus 907/ Jensen Healey as they do not have the progression in the mid range as the Dellortos do and the 907 needs a lot of progression. If you are running a track car, it's in the high rpm most of time, so not a big deal. If it's a street car and you do a lot of normal driving you will notice it. Jetting will help, but it will never be perfect. That said, many folks don't need perfect and only want to run Webers, so whatever. The specs below are about the best I've seen for the Webers with this application-

Idle Jet 50F9
Choke(venturi) 36
Pump Jet 45
Emulsion Tube F2
Air Correction Jet 170
Main Jet 140

Most of the midrange popping should be gone with that. Also, as with Dellortos, it's important that your fuel pump does not exceed 3-4 lbs max (it should be 2.5 lbs, like the original SU pump puts out).