I recently got my new 350 running but am having problems adjusting my carb.It's a holley 750 dp and I need a good starting point just to get it running decent.Right now it's running to rich and fouling out my plugs,and after I shut off my fuel pump It still is dumping fuel into the carb.This is a brand new carb!

Turn Both mixture screws in untill they hit the seat then turn them out 1 and a half turns. This will get you started!

Is there a good starting point for the floats also?

if you dont want to pull the float bowls off then just start the motor up and open the sight plugs and adjust away. (fuel level at bottom of plug hole)

if you do, just adjust the float to about level, half way up, half way down in normal operating position, thats close enough.

as for the idle mixture screws, matts right about 1.5 turns .. and go from there.

what do you mean that the fuel pump still dumps fuel into the carb when shut off.. still fill the float bowls, or something is overflowing down into the intake from the carb?

mike

Yeah it sounds like your float levels are too high. Thats why its dumping fuel. Pull the sight plugs (have something ready to catch the gas). If the gas comes pouring out then start by lowering the float levels a few turns. Tighten up the set screws and fire up the fuel pump and see where your at. You want the front bowl just a hair below the sight plug(try leaning on fender and if it just trickles out your fine), and you want the back bowl to where it just trickles out.

Just jumping in with my 2-cents worth...After you've set your fuel levels & if you are still "dumping" fuel, you might check your fuel pressure. I've had several Holleys where I found that the float/needle combo wouldn't tolerate more than about 7 psi from the fuel pump without letting the fuel past it to "dump" causing a rich condition. They all ran like gangbusters at wide open throttle, but wouldn't run worth a hoot at idle or part throttle. For most driving, I've found that 3 to 4 psi will work just fine. I found my current project to be at 9 psi with a stock mechanical fuel pump. It took completely going through a new carb to finally discover this fuel pressure problem!! I've added adjustable fuel pressure regulators to all (3) of my Holley carb vehicles & have passed this on to several of my friends who all had good results. The adjustability helps you to "tune" the system to the type of driving you participate in. I don't drag race my cars, but I suppose that if you did, you might want to dial the pressure up to 5 or 6 psi for a lot of wide open throttle runs. Just wanted to give you some food for thought in case the other tips don't fix it. Also, when you are setting the mixture screws as recommended by the previous replies, be careful when seating the screws prior to backing them out the 1.5 turns as mentioned. All they need to do is "touch" the seats before backing them out. A friend of mine got carried away once & damaged the seats. We chased mixture problems a long time after that before we discovered the cause. Another tip, depending on what model Holley you have is to make sure to get the choke set properly for cold starts. If not that sucker will "cough" & blow the power valve causing other performance problems that will leave you chasing them. Good Luck.....ODIE.

Change your oil. raw fuel down the cylinder is bad for a new motor and deluetes the oil.
to set your float without starting the car again try the following.

Remove the scew and nut from the needle and seat at the fuel bowl.
The needle and seat threads should be about 21/2-3 threads out of the bowl.
Replace the nut and locking screw.

As odie stated check the fuel pressure. Also if your fuel system is new you may be getting debris in the needle and seat and sticking it open causing uncontrolled fuel level.