No problem with EFI, that's what the fuel today is made for, a closed high pressure systems. The fuel boiling point is very low in comparison to what our engines were designed to run on back in the day. So what to do? We must lower the fuel temp as much as possible to keep it from boiling off... Cool-Carb insulator and block the cross over would be the first step IMO.
Like he said.
This is a simple problem and is quite common.
There are two basic fuel-heat problems.
First we have vapor lock. This was common in the old days as well as now. At one time, many cars had a vapor return line on the filter that routed the vapor that occurred back to the fuel tank. Fuel vapor does not pump very well...and if it did, it would not do much to fill the bowl with fuel. The problem is exacerbated by the use of mechanical fuel pumps that are not very good at sucking liquids into the pump and pump nothing if it has vaporized. Obviously, I think, engine compartment heat causes the fuel to vaporize in the fuel line. Today's formulation does not anticipate this problem as it is formulated anticipating a 43 psi fuel pressure being pushed by an electric pump submersed in fuel in the tank. Fuel under pressure does not vaporize very easily and it is continuously being recirculated back to the tank by the regulator so heat cannot build up in it to any great extent while it is running. When the key is turned back on, the fuel immediately recirculates and any vapor that may occur is pushed thru the canister.
On our older cars, an electrical pusher pump at the rear of the car helps a lot even at lower pressure but steel lines still absorb a lot heat and as has been mentioned in this thread, putting insulation on the line really helps-particularly if the engine has headers on it. No sense in having hot fuel going into the carb when it is running-just gives it a head start on boiling in the bowls.
Using coated headers also really cuts down on the under hood temps.
The apparent problem in this particular case seems to be the fuel boiling out of the bowl when the car is parked. Again we have today's forumlation of fuel making it worse. Often, it may appear that the engine is flooded, but generally, the fuel has boiled out of the bowl via the vent tube as well as out of the intake and heads.
To reduce this from happening, we have to reduce the amount of underhood heat that rises up around the carb as well as the heat transferred from the engine to the carb when it sits. As mentioned, coated headers make a big difference in lowering the ambient temp around the top of the engine.
The other two items have already been mentioned. Block the exhaust heat that is piped into the intake to improve cold weather start up drivability and use an insulator under the carb base and/or a good insulator heat shield that reflects/blocks heat from rising up to the carb.
Putting an ice bucket in the fuel line may help a strip car but it's no solution for a car that is going to be driven further than a quarter mile.
If you live in an area where you think 90 degs is a hot day and you have coated headers and blocked exhaust heat, you may never have this problem so that has a bearing on the subject.
