I have an original rebuilt quadrajet for my 68 nova ss 396.The problem I am having is once the car gets to operating temp and you shut the car off ;it has trouble cranking up or will not crank at all unless you remove the air breather or open the back barrel to let the gas vaporize .It has the vent valve which is at the open position ;when the car is shutoff. The floats are sat at a quarter inch. no nozzle drip either once the car is shutoff .any help out there ;cannot figure this one out.chris
I've read that the fuel in the line between the pump and carb can heat soak and expand pushing more fuel into the float bowl. The the bowl overflows pouring fuel into the manifold. Sounds like your problem. Is this a new problem? Check and see if the line is touching anything that gets particuarly hot. edit: I saw the information in the Doug Roe book and he also states the fuel in the float bowl itself could be getting too hot. Is the float adjustment your using the one specified from the factory?
I don't understand how a carb can cause an engine to not crank. Are you saying the cranking motor (starter) doesn't work right (won't crank) or the cranking motor works but the engine won't run (cranks but won't start)
the car cranks over nicelywith no problem.After it is operating temp it cranks over great also ;you just have to remove the breather or open up the back barrels for the car to fireup;a vapor or flooding problem I am thinking .the float is set to factory setting at quarter inch.Chris
1. Is the exhaust crossover in the manifold plugged shut with carbon? The choke coil may not be getting hot enough to properly open the choke. You try to re-start a warm engine, but the choke thinks it's cold, and shuts too far. 2. Is the heat riser valve working like it should? Has it been disabled/removed? Stuck shut? If it never closes, the choke may not properly warm up. If it's stuck closed, you may be getting the manifold so hot that it boils the fuel in the carb. Either way, you could be getting the hard-start when warm. (more likely with it stuck shut) 3. What temperature does the engine run at? If it's got a marginal cooling system, the carb may be getting warm enough to boil the fuel. 4. How does it run in general? Reasonable fuel economy, reasonable power, runs smooth, no stalling, no backfiring, etc? Or are there other problems even when you get it to start? When you "open the back barrel to let the gas vaporize", are you opening ONLY the air valve, or both the air valve and the throttle?
