Stumbling Problem - Help

[dznucks]

I need some professional opinions.

After letting my truck sit over the weekend, it seems it has developing a bad stumble in the engine. yesterday it seemed to only stumble during driving conditions. Last night i went through the electircal side, wires appear ok, cap and rotor are ok. didn't pull the plugs but they are all tight. The carb seems to still be tuned correctly floats are normal and the idle settings are good.
Last i drove the truck was last friday and everything seemed alright.

This morning it appears to be stumbling alittle worse and even stumbling at idle. I am going to change out my fuel filters today but i am not sure thats the problem. I suspected the problem to be electrical at first but now i am leaning more towards a fuel delivery problem.

Can ya'll give me some opinions as far as what to check and maybe share some of your personal experiences with the same type of issues.

oh, its a '69 with a basic 350 and a demon 625, nothing fancy.

[ChevyC102007]

My truck is doing the same thing but it only does it when the truck is still warming up. Im running the stock 350 with a Q-Jet carb. Im thinking it may be something to do with the choke. But you can get a gauge so you can check your fuel pressure. I think for a carb'ed motor its somewhere between 5 and 8 psi, I may be wrong. Check those two things and that should give ya a place to start.

[dznucks]

yep - your problem is the chole adjustment. i have the same problem too aside from this other issue. you should notice your problem get worse as winter sets in and the cooler temps cause the choke coil spring to take longer to open the choke.

however, this is a major shutter while driving. something that is noticable to the guy standing on the street.

it is something in the fuel or electrical side. i have tried to get it to backfire by stomping on the gas, but it wont. so i am leaning more towards a fuel issue.

[ChevyC102007]

Ok I figured thats what it was, It usually happens when I give it abit of gas too (rev the motor). Have you called Demon support? they may have an idea too as to what the problem is.

Are you still running a mechanical fuel pump or a electric pump with a regulator? Either way try going ahead and replacing the fuel filter and check your fuel pressure. If its a mechanical pump the diaphram may be going bad.

[71tahoe]

There is a thread on here that described some demon carbs having shavings from manufacture still in the fuel bowls.

[dznucks]

I have called Demon support. i believe there is only one support guy and he isn't the most eager individual to provide assistance.
The problem ended up being a loose terminal in the cap. it was causing weak and erratic spark in cylinder #5. i put a ignition spark gage on each cylinder.

as for the fuel shavings in the fuel bowl. when i got my demon i noticed that there was basically no deburring done throughout the carb. i am not completely inmpressed with the carb. my old holley in dire need of a rebuild was a better carb.