Need some help. My car is not running real well and I’m not sure where to start. I suspect my problems are ‘carb’ related but I’m not sure.
Car is a ’76 T/A with L78 400, auto. 48,000 original miles. Engine has never been apart and the only mods have been the removal of all emissions related components and the addition of headers and 3.42 rear gears. Everything else is stock.
I recently had the engine bay apart to do some detailing so I changed the plugs, wires, distributor cap, and coil. The hot air choke had been disconnected by the previous owner so I hooked it back up. The engine had been running ‘fair’ before I did any of this so my hope was that it just needed a mild tune up (guess I was wrong).
The carb was rebuilt about five years ago but I do not know who did it and I’m pretty sure it was a ‘stock’ rebuild. This was before I really started learning about Pontiacs so my ignorance is the culprit for not being more concerned about “who” did it and “what” they did.
Here are the symptoms – fires up after about three cranks. I need to keep my foot on gas pedal for a couple of minutes until it will idle on it’s own @ 500rpm. It used to idle at 750rpm before I hooked up hot air choke. When I first take off, it sputters and even mildly backfires a couple of times. After the engine warms (160 degrees), it starts to run better but still not great…..and it is sucking down gas big time. Throttle response is very poor until engine warms but is still poor even after it does……UNLESS I jump on it. If I punch it, it will take off like nothing was wrong…..and if I’m doing, say 40mph, and I go WOT, it kicks down like it should and goes like a bat out of he**.
So, to summarize, it runs like crap when until it warms and still rough even when I’m just driving it around…..BUT….seems to be ok at WOT.
Any ideas, suggestions would be GREATLY appreciated. I can diagnose and correct some basic problems on my own, but when it comes to this kind of stuff, I don't know where to start or what to do.
Thanks !!