Hey guys- I am have been having a problem with my car that I cannot seem to fix. The motor is a 350 chevy, mild cam, 650 holley. In march my father and I updated the distributor to a HEI , new coil, wires and had the carberator rebuilt. The timing seems to be right when I put a light on it (around 7 degrees advance) but the vaccum off of the manifold is low. The car runs fine, but when I drive at high rpm for 10 or more minutes, the car starts to want to backfire. It runs like shit until it has had time to cool down for at least an hour. I have looked for wires close to the engine, but everything seems to be ok. We also added a ron francis hot start kit, which could be the culprit. My dad also said it may be vapor lock, but the tank is vented. Has anyone else had this problem, or know of anyone in this part of the state that could look at it with me, since my tools and knowledge (father lives in north LS) are fairly limited. Thanks in advance.