If the choke is not opening all the way this is usually caused by either a misadjusted choke or improper voltage supply. This can also cause fuel leaks through the airhorn gasket. When this happens, the fuel can get forced through the venturi booster and drip into your engine. Heat soak is when the heat from the engine compartment heats up and can boil the fuel in the float bowls.
With today’s fuels, another cause of leaking fuel could be heat soak. Measure the float level by turning the carb lid upside down and placing a 7/16” drill bit between the airhorn gasket and the top of the outer end of the float just past the inboard float radius. Check float level, the float level should measure 7/16”. If there is fuel in the float replace float. While the float is off, shake the float for any signs of fuel in the float. Take the top of the carburetor off and check for debris in the needle & seat, also inspect the needle tip to be sure it has not been compromised. The fuel pump pressure should be no more than 6.5 p.s.i. Below are a few reasons why you may see a fuel leak along with some possible solutions. There are many different circumstances that would cause fuel to leak out of a carburetor. Be sure the timing chain/camshaft was installed correctly. 100” and the minimum exhaust clearance should be. Was piston to valve checked, the minimum intake clearance should be. If stock heads are being used with rocker studs, be sure they are thread in rocker studs if they are pressed in and running a high lift cam, the studs will need to be pinned/studded or converted to screw in rocker studs. If guide plates are being used, be sure the rocker arms are non-self-aligning. Also, be sure the slot in the rocker is long enough to handle the lift and the rocker is not binding on the rocker studs. Be sure the rocker arms are not hitting the valve covers or valve spring retainer. Be sure your running the correct valve spring pressures and the springs can handle the camshaft lift. See How do I break in my cam for more info on breaking in a camshaft. If the cam was not broken in properly, most likely the cam is going flat. First be sure cam was broken-in properly. Be sure the distributor is installed correctly and the firing order is correct. Also, be sure the carburetor is not flooding. 
A rich or lean carburetor can also cause engine to backfire.
Check your carburetor calibration and operation. If the cam lobes are going flat this can also create a backfire. Listen for any signs of a camshaft going flat like noisy valvetrain. A vacuum leak can cause low vacuum and create a lean condition and can cause engine to backfire. If the camshaft is installed incorrectly this will lead to the valve opening at the wrong time and can cause the engine to backfire. A leak down test can help determine if valves are being held open. Over adjusted lifters can hold valves open and cause the engine to backfire. Many things can cause engine backfires, below we will go over a few things that can cause backfires after a camshaft is installed.
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