I am having a hell of a time trying to figure out my low speed cough and sputter. It feels like it isn't getting enough fuel. At higher rpms, 2500 to 5000 it runs great. No lag and it takes off. It is a mild build 302, Performer intake and a 1406 carb. It has a electric fuel pump mounted by the tank. I have changed the metering rods and the primary jets, but it still does it. I did notice today that there was an air bubble in my see-through fuel filter, should that be there? I just gave it a tune and found the timing to be way off. I have it set at 10deg right now, with a fresh set of points and condenser. Help! I got beat off the line by an Escort! Rod
Those little gremlins can be a real bi*** sometimes, if I remember right the 1406 is 750cfm and can really suck some air into the engine. On mashing the beast off the line, the small head ports and valves can only accept a small portion of it, especially with a stock cam. Yet there is that immense volume still in the intake plenium and until it reaches high rpm to use most of it, a lean fuel mixture will exist. Have you tried moving the accellerater pump rod to a different hole? Also there are several different spring rates for the pump itself. The owners book for the carb should explain much of this, and no there should be no air in the fuel system, check all lines and connections for suction leaks etc. Have you also tried backing down the timing to 6 or the like? Are you running a choke on this carb?, it just sounds a lot like you need to richen up the mixture off idle. On the antique stuff I've had over the years, most had manual chokes and first thing on a cool morning without the choke, they would cough and fa**, even backfire if you mashed em down hard(lean mixture). Just a few things to look at, rear end gear ratios and torque converter stall is a whole other subject.
302 falls on face I have tried the timing, 6deg to 12deg, no luck. I have moved the accelerator pump, one closer to the carb, no luck. I have tried richening the fuel mix, no luck. So, now I will try to find the air leak in my fuel line, I hope that does it. It's really starting to piss me off. Thanks for all your help. Rod
i had a 750 double pumper on my 351w, mild setup and it did the same thing. i changed to a smaller holley 650 double pumper and the stutter went away. i'm not sure if it was the smaller carb or the fact that whoever had the car before me modified the 750 and maybe screwed it up. my thoughts were that the 750 was a little too big.
302 falls on face Well, I have the 650cfm 1405 on my 302, and I also have one on my Scout with a 345 and I have never had a problem on the Scout, maybe I will swith carbs and see if the problem goes away. I just checked all my fuel lines and couldn't find any leaks. I changed my air filter also. I am stumped. Rod
LOL!!!! I beat an escort off the line tonight in my 200 4door!!she eventualyy got me but i quickly caught up.although my heart was pounding doing 30over down main st.
With your discription of running ok above 2500 makes me think there is a possibility of water in the bowl coming from the tank. Water being heavier than gas, what can happen is the jets meter fuel near the bottom of the bowl and will alow water in with the fuel and cause a cough. The power valve is higher and when it opens, will give clean fuel and the engine takes off. Worth a check, some dry gas in the tank and some patiance till it works.
sounds like it's a bit lean to me. A lean carb will pull hard on the top end, but will stumble, stall, backfire, and overall run like &*% on the bottom end. I'd first try changing the accelerator pump nozzles to about 5 sized larger...to start. Also check the timing just to be positive. Hope this helps some.
Solved the problem! The problem was a faulty mech. advance on my distributor. The springs were worn out. I put in a reman distibutor from NAPA, and what do you know! It runs great! Now, I just have to figure my carb tuning. Thanks for all your help. Rod
