what cam is in the car? are you drag racing or mostly driving on the street?
Do you already have dual exhaust?
With the cost of stuff, if your car is running ok, do you want to
spend the money on a larger carb, that on the street there will be very little
difference?
That said, I am using a #1406, 600 cfm but, amost used the 500.
I have using a performance cam, Mopar 4452759 And the correct valve springs that go with it. I am using # 302 heads on my 318.
Part Number: DCC-4452759
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,200-5,200
Intake Duration at 050 inch Lift: 221
Exhaust Duration at 050 inch Lift: 228
Duration at 050 inch Lift: 221 int./228 exh.
Advertised Intake Duration: 260
Advertised Exhaust Duration: 268
Advertised Duration: 260 int./268 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.430 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.450 in.
Valve Lift with Factory Rocker Arm Ratio: 0.430 int./0.450 exh. lift
Lobe Separation (degrees): 110