My skylark is doing something a little strange and I would like some opinions on what it could be. The car cranks and runs well with one exception. When I hit the throttle quickly to the floor it stumbles badly and even cuts of if held. Now if I hit it to half pedal quickly there is no stumble. If I gradually increase to full throttle no problem. This happens when driving and when in neutral. Any Ideas?
That sounds like an accelerator pump issue with the carb. Is it a stock-type Q-jet? It may need a rebuild, or at least a cleaning and a new accelerator pump. How's the ignition system as well? Do you still have points in there? HEI?
It is a completely stock 72 350. Original Carb and Points. Thanks for the help. Ill check the accelerator pump tomorrow.
You might want to do a total tune-up on the engine; points/condenser, cap/rotor, dwell and timing, plugs/wires. Then try tuning the carb and if needed rebuild the carb. The ignition tune should take an afternoon and then you will know that everything is good with that aspect. Then if the car still runs bad you can check carb, fuel lines, and even fuel pump. Not to say that fuel pumps are disposable, but they are only $20 to $25 on northernautoparts.com. For that cheap why have any doubt? And you might be able to check timing chain slack/slop when you have the fuel pump off too. At that point it should be running pretty good. and if not, you may have a better idea of where to look for other problems.
Sorry for not updating sooner. I checked the accelerator pump. Didnt look like it was working(ill reemphasize "didnt look"). I remembered I had a Rebuilt quadrajet I had bought awhile back, so i figured id bolt it on. It is coded and built for a 72 gs 455(i read later that that might have been a bad idea?). Anyways, when I went to take off the old carb the bolts came out by hand and I noticed the fuel line was slightly crinkled right before entering the carb. I went ahead and bolted up the rebuilt carb and it cranked right up. Throttle response was great no hesitation until I saw a small leak coming from the fuel lineou: . I shut it down and am waiting on a new fuel line from inlinetube. After looking at the quadrajet after it was off the car, It looks like the pump might not have been the problem. I was comparing it to an edelbrock carb off my GS which was easier to see. Needless to say I feel pretty stupid and wont really know anything until I get the new fuel line in. I was browsing some post today and saw where the 455 carb might not work well with certain 350 set ups. Is that the case with a completely stock motor? Would the carb being loose have any affect on what was going on? Bear with me guys.... Thanks for the help.
Would be a pretty major vacuum leak and the likely cause of the problem. You may of heard a hissing sound while running it with the carb loose that went away after the carb swap. As for the 455 carb causing other problems, a more experienced member would have to answer that.
In some cases the 455 carbs work great on the 350 and in other cases they require modifications. As long as you are not running too lean or too rich it should be fine.
Thanks Sean, I was hoping you'd write back because it was you I saw talking about it. Hopefully the fuel line will be in, in the next couple of days and we can resolve this once and for all. Just happen to have a new video camera and will try to take a video for everyone.:3gears:
Got the new fuel line in today. Put it in and started her up with the 455 carb. Damn thing was leaking like a faucet out of the top gasket. I tightened everything I knew to tighten on the carb and still couldnt solve it, so i put the original carb on it and the thing ran like a dream. The accelerator pump is indeed working and the stumbling must have been caused from the carb being loose. I have the interior out of it right now, but once I get it back together Ill get that video I promised. Thanks for the help, Jim
