carb main jet

[allanr5gtt]

hi all i have been running a 150 main jet for a while and the car has been over fueling. as i have turned the boost down to 16 psi i thought a should put a 120 main jet in and see what happening on the lm1. once fitted the 120 main the car idle fine and on wot it pull's well but on part throttle it lean out and try's to die. any idea's? the 120 is all clean not blocked?

[car.crash]

what size is your needle, second stage and air corrector?

[allanr5gtt]

ac 0.9, e1 std, e2 1.35 not to sure on the needle?

[Markey Mark (BD)]

What size is the venturi too?

[Spooky]

mike spencer engine, probably a mike spencer carb too which means 27.5mm :p

[allanr5gtt]

yeah bored out to a 27mm and a yeah is was first built by mike.

[Markey Mark (BD)]

yeah bored out to a 27mm and a yeah is was first built by mike.

I'd personally go back to a 25mm venturi if your using a standard 1.2mm mai jet mate.