start car then spray carby cleaner around the top of the carby and down into the jets while holding the throttle to about 3000 rpm the revs will die a bit when u do this so keep holding the throttle open until revs pick back up if the choke is working properly it should be fully open at operating temp
If you have to turn the choke on a little, the motor is starving for fuel. need to clean the carburetor
check/clean the earth lead to the motor. it will be from neg side of battery to the motor. as at night with the light on it might be taken most of you earth to the motor that is worth a try
Check here for headers & motor mounts: http://www.critesrestoration.com/comet.htm You will also need to modify the front suspension to put an FE motor in a Falcon.
it is not okay to run your motor like that your choke is what controls air to gas mix ratio on engine, what you will have to do is take your carb apart and clean. it is fairly easy you usually only have 3 bolts holding on your float bowl then you have your float inside and a few jets depending on model of carb, which you spin out and clean then you have your fuel adjustment and air adjustment usually on the side of carb pull them out and clean check your points on the adjustments if smooched in than you will need to replace, then clean your thoat of the carb and you choke butter fly and your problem should be fixed
If it runs with the choke on, Then it will not do any good to adjust them. It is running lean/ not getting fuel. The carburetors have dirt in the fuel jets and that is why it won't run when choke is off. When choke is on that richins the fuel up and it try's to run. Need to clean the carbs out.
There should be a dip stick at the back of the motor. But only if its automatic
that engine has no choke
similar to xf falcon
time to rebuilt carbs. when you choke a motor of any kind what you are doing is cutting of the air so the motor pulls more fuel. so this meaning that when you turn choke off not enough fuel is getting to the motor.
MY lawn mower will start to sputter if I run the choke on after the motor is warmed up. It's getting fed too much fuel. Ease off on the choke and it will run better, usually.
check that choke is operating correctly
Try replacing fuel filter, & Check that float(s) are working properly.