1974 Volkswagen Beetle

1974 Volkswagen Beetle 4 cyl Two Wheel Drive Automatic

I have a 1974 VW beetle automatic stick. I used a repair kit on the pic 34 carb, replaced to cracked heads, one fuel pump, one starter, and several seals. When I drive for more than 30 minutes, the engine slowly loses power and shuts down. The car will not start until it rest for and hour or more. Then it starts and run as if no problem. Some one suggested that the heat from the engine could be evaporating the gas in the line causing the engine to starve for fuel. I have checked for leaks along the fuel line, blown air through the line, and still have the same problem. Please offer help in correcting this problem.