Vapor lock is caused by usually a fuel that vaporizes too easily at too low a pressure (in the line) due to under-hood heat and not enough pressure on it - which would run great if it could make it to the combustion chamber first. Depending what your compression is you could add 5% kerosene up to 25% for cars from the 20s with very low compression, like 5:1 or less. None of these contain lead and so should not damage a catalytic converter if you have one, HOWEVER too much IMCT will prolong the burn and may result in unburnt - STILL burning HOT gas being exhausted in the exhaust cycle. The carb should not flood even with the pump running unless it is putting out enough pressure to over come the float bowl shut off mannerism mechanism of the carb. Overview. This Holley FPR (12-804) use to be a perfect choice to solve the "too much fuel pressure" produced by the aftermarket fuel pumps on vintage VW. . Too much fuel pressure for a given needle and seat assembly can overload the needle and seat and may cause flooding or drivability problems. Some cars are much more apparent to vapor locking than others, I"ve never experienced here in NJ with either of my older Packards which see all kind of hot summer driving conditions. wrapped around the fuel lines. As a single solution, or partnered with products from other Holley companies - Hooker Headers(R), Flowtech(R) Exhaust, NOS(R) Nitrous, Weiand(R), Earl's Performance Plumbing(R), or Diablosport(R)- Holley products can give you the edge you need over the competition. For now, in 70 degrees ambient, the bowls are 100 F. at shut-down and after 15 minutes they rise to 115 F. At these temperatures the engine starts back up fine, but I believe another ten degrees will be in the problem zone. That was in the 1990s, so you can project to more current times and suspect we have something more sophisticated now. For any further assistance please feel free to call us at: 1-877-238-2623 or visit the nearest Advance Auto store and one of our representatives will gladly assist you with any questions or concerns you may have. Then, we got what was loosely described as winter gas, all year round, with RFG.