stumbling during accel.

[plastic-idol]

finally got the car back on the road. she' running smooth, except for an occasional stumble, usually during accell or up hills. when in park or neutral there is no problem, only in drive. could this be the carb, or my timing. the timing was just set by the shop. it happens most during acceleration from a complete stop.

 

[Anonymous]

Look for a couple of things:
1.) If the choke is not opening up very far, the 'stumble' will be there just off of idle after the engine is warmed up to the point where the choke is not needed.
2.) A bad accelerator pump will not squirt enough gas when starting up or changing to faster speeds. You can check this by looking into the carb and stroking the throttle linkage: it should squirt.
3.) If the choke is opening and the pump is squirting, next item 'up for bid' is a vacuum leak. Look at the carb base (tighten up the mounting nuts), the top of the carb (tighten up the screws on top), look for open vacuum lines or ports on the intake manifold and, if power brakes, check for a good brake booster or rotted hose going to the brake booster. If you have power brakes, but they are not acting consistently, this could also indicate a brake booster problem.

Hope that helps. Happy New Year!

 

[CobraSix]

The other thing, this is a very common problem with the Autolite 1100s. I'm not sure which carb you are running.

Slade

 

[strat1960s]

I have the same problem with my car. I am running a Weber 38 DGAS. It too stumbles when accelerating from a stand still. The only thing I can do to keep it from stalling is let it roll at idle and gradually give it some gas. I was thinking it could be timing.

 

[Anonymous]

Hi strat1960s,

The stumble you describe sounds very much like your main jets are too large. Over jetting the 38/38 is a larger problem than with the 5200 or the 32/36 as the 38 is not a progressive carb. Both throats are live at all times. Check your main jets. I would suggest 150's as a good starting place for a 200 I6.

Steve

 

[plastic-idol]

Well, bad news and bad news. The car died last night. the stumbling and skipping kept getting worse, especailly from a dead stop. The shop replaced the coil and reset the points, and it ran fine for about five minutes down the road, then did the exact same thing. Hopefully they'll actually fix the problem this time. As far as I know, the carb is an Autolite that we got from Pony Carbs.

 

[addo]

That's a worry, what they did. Unless they can prove the coil was defective and the points way off, theirs is stumbling in the dark material.

Fuel pump, float level, ignition wiring - all can be possible contributors. The good news is it's almost certainly a small part that can be replaced in the car (even the whole carb if need be). Not like a bore is split or something. Yep, it can be frustrating, even infuriating, but trying for a logical, sequential overview and testing will see you isolate the problem, then resolve it.

Adam.