My trucks been having trouble starting up correctly. When I go out in the morning, I can hit the key without pumping the pedal, and it starts but bogs down for a few seconds. To start it when its warm or if I've pumped the pedal, I have to floor the gas to get it to start. I realize its starting too rich, and it seems to be the choke pull-off. I probably have it set to 1/4" (too much, I know), but I had my brother turn the key for a few seconds while I watched the choke, and it wasn't even opening half that. I replaced the pull-off a while back and I've verified that it holds vacuum. Any ideas

 

To start a carbureted engine in the morning for the first time that is driven daily, you should first push the accelerator pedal down to the floor at least once. This will set the choke. Then start the engine. On a warm or moderate day, the engine should start right up. On a very cold day, you may need to push the accelerator pedal down twice (once for the choke and another for a little extra fuel) before starting.

After it has been driven for the day, it should start up without giving it gas at all, unless it has sat for 5 hours or so, then you may or may not have to push the pedal down half way to start the engine.

See video in this thread:
https://www.ford-trucks.com/forums/1...art-video.html

 

Im aware of the starting procedure and normal carb behavior; my '62 Plymouth starts rather well. Im basically trying to figure out why my choke pull-off isn't pulling off all the way. Autozone had 2 or 3 listed when I got the new one, could some pull off with less vacuum than others and maybe I got the wrong one?

 

IIRC ,, the pull off is adjustable ...

 

I've adjusted it to spec, and played with different settings. Its just not opening all the way like its not receiving full vacuum.

 

Doesn't it have an adjustment on the back for a hex?...

 

It does, Ive adjusted it. I'll have to get a video tomorrow to show y'all what I mean.

 

OK .. The bad part is you only get a minute or so per day to set it ...

 

What do you mean by not opening all the way? The pulloff is only supposed to crack the choke plate - just enough to let air into the throat of the carburetor, yet still mostly closed to make full use of the choke.

Before you start the truck with a cold engine, pressing the gas pedal once will make the choke snap shut completely. Cranking the engine over will create enough vacuum to depress the choke pulloff, which opens the choke ever so slightly. Once the engine fires, it creates enough vacuum itself to hold the choke open on its own. As the choke warms up, the choke spring opens the choke plate further, until the choke is opened far enough that it's no longer held by the pulloff. The pulloff is actually engaged the entire time the engine is running; however it only has an effect during the first couple minutes of running.

 

You can load the choke by loosening the clamp that holds the thermostat and turning the thermostat 90* toward the back of the engine. Then you can set it anytime.

Oh, ok, this makes sense. Maybe the starting issue is timing related then.

 

Anyone know the pull-off clearance for a '79 F150 w/ 351m & 2150? I've searched around but the answers are inconsistent.

 

Never mind. I used a 7/32 drill bit and it started much better.

 

That should be close enough.

 

It did smoke a tad when it started but, at least its starting properly now and idled perfectly.

 

I don't feel like starting another thread so I'll post this here. I keep noticing this oily puddle right next to my carb. Leaky carb shaft?