I have that system its not really vapor lock. the fuel is actually boiling right out of the carburetor and yes I have a wooden spacer. I did many different tests with it.and the ethanol is the key problem any non ethanol was fine. I could let the car run in the drive way and once the car got warm which sometimes the engine wouldn't be over 175 and I would start missing and pop the hood and you would see it first start spitting out the squirters then it would start over flowing out the vent tubes like a volcano. if you pop the hood quick enough it would get the heat off the carburetor and would run fine. Since I put it the return in it has helped 100 %