I am a new guy. Have just started trying to make the 67 400 he(son) bought safe to drive. Well I have been working fuel pump dumping fuel for the last couple of days. Took the pump off, repaired the supply line, found the return line deadend on right side of engine compartment. Went to the autoparts store for new pump. Well there happened to a "expert" on early GM big blocks in the place. He said the early carburetors would flood out with "normal pump pressure" so GM put on a pump that supplied a lower pressure with high volume and returned the unused fuel to the tank. So what that means is if you are a purist and want to use the original carb. you will have to have the return line. You can not use a "stock GM" pump and plug the line as pressure will go to high at low power setting. In my case I intend to hook up the return line, reinstall the pump and drive on.
Have just started trying to make the 67 400 he(son) bought safe to drive. Well I have been working fuel pump dumping fuel for the last couple of days. Took the pump off, repaired the supply line, found the return line deadend on right side of engine compartment. Went to the autoparts store for new pump. Well there happened to a "expert" on early GM big blocks in the place. He said the early carburetors would flood out with "normal pump pressure" so GM put on a pump that supplied a lower pressure with high volume and returned the unused fuel to the tank. So what that means is if you are a purist and want to use the original carb. you will have to have the return line. You can not use a "stock GM" pump and plug the line as pressure will go to high at low power setting. In my case I intend to hook up the return line, reinstall the pump and drive on.
