Can anyone help me? I recently finished a complete resto on a 70 GS and can't drive my car. It's killing me! Here's the problem. I had the 455 completey rebuilt and it ran fine on the dyno. I am trying to keep the car as original as possible, so I kept the original Q-Jet and had it rebuilt. Problem is I can start the car, but it won't stay running. The carb rebuilder claims the carb was bench tested and there is no reason it should not run. I followed the assembly manual exactly when I hooked up the vacuum lines, but should I do something different? Also I don't know if I hooked up the manifold choke spring correctly. Is there a way to set it before attaching to the carb? Can anyone help me? Thanks,
Once it starts, I can keep tapping the gas pedal and keep it running, but I can't hold it in any one spot before it wants to quit. Thanks for your help
If the carb was flooding, you should be able to see gas spilling down the carb after it stalls. If this was the problem, you would of had to hold the gas pedal down to the floor while cranking to get the car to restart.
Thanks for all your input. The carb is definitely not flooding. Same distributer, different carb on the dyno. I spoke with the carb rebuilder today and we are thinking that there is a vaccum leak somewhere, possible in the trans kickdown line. I am going to check all the possibilities for the leak tomorrow. I am keeping my fingers crossed. I will be back if this doesn't work!
It is possible that the incorrect kit was used for the rebuild. Try this: set both mixture screws @about 4 turns out, after bottoming. Some carbs require a little more, but try that. Does the engine take gentle throttle? If the carb was really bench tested, have the rebuilder show you the flow bench and the analyzer used for the testing. The carb may have a very low float setting. A rule of thumb is to have the top of the float being parallel to the top of the bowl. It is also possible that the gasket is leaking or is incorrectly installed between the air horn and the bowl. Idle fuel flows, based on air flow, from the bowl, into the air horn, using tubes, and back into the throttle body, to the jets. If air is leaking into this path, the mixture will be very lean. The following procedures will require carb disassembly; let's start with what we have and go from there. I suspect lean mixtures as tapping the throttle is allowing the engine to run on the accel pump shots. Ray
Block off every vacuum port on it - at the carb fittings, and see where you're at. How far out are the idle mix screws? Double-check the carb-to-manifold gasket, make sure it's the right one. If you think it might be leaking, you might try some stuff called "Leak-Lock" available wherever they sell stuff for fitting gas/propane/lpg lines. Impervious to gasoling, it really works well. Choke - The stock choke coil should push up on the linkage when cold, and pull down when it's hot. If you manually hold the choke closed a bit, will it keep running? Do you have a Chassis Manual? Look in there for the troubleshooting section if so... Don't give up!!! It'll get better :3gears:
What is your choke doing. sounds like it is not opening, or its not closeing enough. if its not the choke, sounds like the car will only run off of the accelerator pump, meaning there is a problem with your idle circuits. I'd check for some good awful vacuum leaks, and play with the mixture screws. really sounds like your choke is wayyyy out of adjustment..
All your help is appreciated I have been trying to get back to the car, but that damn work thing keeps getting in the way and taking up all my time. I have blocked out the whole day on Saturday to get this car running- No exceptions! I appreciate all your advice and I am sure one way or another, I will get the beast going on Saturday. I will keep you posted-
Great idea, unfortunately I only own one Q-Jet for the Buick, and I don't have the dough to round up another.
Thanks for all your help I appreciate all the input. It turns out it was a vacuum leak. I have it running and it is awesome. The only problem I have is that the leak was in the Power Brake Booster. The Booster I put on the car is rebuilt and replated original unit but at this point I am running it without the booster hooked up. Does anyone know if it is possible to repair the Booster without completely taking the brake system apart? I was told I can disconnect the Master Cylinder and repair the booster while on the car. Does anyone know if this is possible? Thanks
Re: Thanks for all your help Well, that depends on where the leak is. If it leaks at the seam, you might be able to do somthing, but if it leaks on the back, you probably will not.
