No, I am not drag racing, but whenever I first put my foot on the accelerator to start from idle, I have to feather the gas. If I just push it down about halfway, or even try to floor it, the car will die. Once I get past this inital feathering, the car runs great, and when going down the road I can hit the gas, and not have any problem. It seems to be an off-the-line stumble. Any clues?
Mine used to do that.......it's very annoying! :rant: it's your accelerator pump. I had replaced the accelerator pumps in both my carbs and the problem returned. I discovered that the pump plunger NAPA kept giving me had a skirt that was too short. When I was able to get a pair of good ones with a long enough skirt my stumble went away and stayed away. Since the skirt is made from what appears to be leather, you need to soak it in gas for a while and then stretch it out a little before installing it. You should also check the adjustment, the specs come with the instructions if you buy a carb kit. If you get one from NAPA look closely at the pump before installing it.......it has a sleeve over it so you can't see it until you open the seal on the package to look at it, so open it in front of parts guy so he can see for himself. The skirt should extend at least almost to the bottom of the brass piston. If it doesn't, it prolly won't work properly. I had these extra ones in my private stock :Brow: .......in the photo you can see the defective one with the short skirt. The one on the right is still a little short, but should at least work better than the other one. I hope this saves you a little grief:
Thanks Joe. I purchased a rebuild kit for the Carter last year. I'll have to dig through it and see what the accelerator pump looks like in the kit. I'm also going to check the distributor to make sure the vacuum advance works.
You can also try switching the acc pump linkage to a different hole. When miine was in the highest hole it did the same thing as yours. The middle hole works great for me. Mark
Same problem I was going to start a new post, but this is the same problem I'm having with the AFB on my 65 Gran Sport :af: Without exxagerating, I know I have had my carb off the car and apart about 10-15 times in the last 4 day's. I don't consider myself a stupid person, but this carb has defeated me every day for the last 4 day's,cannot figure this stumble/flat spot out. I just bought this car, and the guy I got it from had *just* gone through the carb before I got it. I finally ordered a new carb kit from the part's store today, hoping that the guy before me had purchased the wrong kit, and there was a possible gasket issue with a vacuum port or??? Idle's fine, wide open throttle fine, but that spot where you need it to work the most(just off idle) and at cruise speed, it just stumble's,sputter's,and fall's on it's face, tries to die,etc. I hope my new kit has this other Accelerator pump, and that it cures my problem o No:
:Smarty: Make sure to pay attention to the two check valves. One is a spring loaded ball assembly near the pump well that threads in. Put it up to your lips and blow through it; should work in only one direction. The other one is a brass piece with a point at one end, located under the squirter cluster. Make sure it moves freely and the pointy end goes down. Hope this helps.
Well, I finally got around to tackling this problem. It only took me three years! I've been so happy to have a well performing carb except for the stumble off the line, I had to come up with the courage to mess with it. Long story short I went to NAPA and bought a new accelerator pump. It cost me $11.49, and was a special order. I couldn't see it before I ordered it, and it ended up being a short skirted one. I took the top off the carb off and tried to push down the old accelerator pump that was put in when the carb was rebuilt previously before I bought it. It did nothing. I tried the new pump, and wouldn't you know it, it squirts gas! I buttoned everything back up, and went for a slightly disappointing test run. Now the car doesn't stumble off the line, but in fact at speed it kind of chugs like it is now getting too much gas. I've adjusted the linkage for the accelerator pump to the hole that gives the least amount. As you take off all is fine, but once you get a little into the gas you have to press deeper to get a squirt or the car just bogs down. Take a look at the old vs. new accelerator pump. I see no way the previous one could have worked with the wrong end on it. So here is what I am thinking: Since the carb was previously rebuilt with a pump that didn't work, was it someone tuned to get around this problem? Do I need to start messing with mixture screws, etc, or is this problem limited to the accelerator pump circuit?
Found the stumbling problem! I bent the metering rods when I tried to just sit the top of the carb back on the base without first removing the rods. I had some spare ones to fix the problem.
