Vapor Lock/Fuel Perc:Fuel Line "Re-Route"?

Do the Fuel line mod and put in a heat shield (see here; pictures here). Make sure the manifold heat control valve is free to turn.

Install a vapour-bleed fuel filter (NAPA Gold 3040, for example) and run the ¼" vapour line (proper fuel line hose and/or metal pipe, please, not just generic rubber tubing) all the way back to the rear of the car. Because you are working on a '71, you needn't go through the hassle and (manageable) danger of attaching a new tube to the fuel tank itself. You can add the vapour line fitting to the top of the vapour separator in the trunk of the car; see here for detail on how the '71 (+'70 California) evaporative emission control system works. While you are reading up on it, take note that it is aggravating the problem you're experiencing, because fuel vapours accumulate in the crankcase after engine shutdown and flow freely into the intake tract (making the mixture too rich) as soon as you sit down and start cranking. You can eliminate this part of the problem by moving vapour storage from the crankcase to a '72+ type charcoal canister with a purge valve as described here. No changes would be needed at the back of the car to add the canister, just plumb it in as described and install an easily available '72-up crankcase breather (without the extra hose fittings).

Other notes:

• You say it's got a "fresh carb". Uh-oh, what does that mean? If you got a "remanufactured" unit from the parts store, I surely hope you kept your 40k-mile original; "remanufactured" carbs are almost always unworkable junk.

• An electric fuel pump, IMO, will cause more problems than it solves -- discussion here and here.

• Make sure you are using the correct starting technique. For a hot engine, hold the accelerator about 1/3 of the way down (do not pump it!) while cranking, and hold it there for a second after the engine catches.

• Your car will run a great deal better if you set the initial timing at 5°*BTDC instead of the factory 0° (TDC) spec. And if yours happens to be a California car, check for a widget with a wire running to it placed in the vacuum hose from the carb to the distributor. Bypass it by running a hose directly from carb to distributor.