When I bought my truck, somebody had adjusted the choke to the point that it wasn't doing anything at all. I have since rebuilt the carb and, not knowing where else to put it, just put the choke dead in the middle of it's adjustment range.

The truck runs great for the most part and it has absolutely never failed to start. It just has a few "quirks" that I thought I would run by you guys and see if they are normal. The only other vehicle I ever drove with a carb is my dad's '46 chevrolet and it has a manual choke, so I'm not real experienced with electric chokes and such.

Ok, here goes. 1974 F-100, 302, 2bbl, electric choke. Any of the manifold ducting and such is gone, so I have replaced the air cleaner housing with a simple 14x3 filter.

When the truck is cold I can go out, step on the pedal twice, and it will fire right up every time, it has never failed to start even on a few mornings when it was down to around 15*F.

When the weather is warm, say 45*F+, it will run without a hiccup. My only complaint would be that it seems to sometimes not come off of the fast idle cam unless I floor it at some point. Nothing in the linkage seems to worn out or binding, so I just kinda assumed that maybe in my regular driving I don't press the throttle enough, so that's not a huge deal.

When the weather is cold, the truck starts fine and will drive pretty good until I get a ways from the house. Sometimes in as little as 1/4 mile, sometimes as many as a few miles, it will develop a hesitation when I give it some throttle, this can happen when the temp gauge is still reading stone cold, or it could have started to climb most of the way till normal. Usually if I can blow past this and get it up to road speed for a few minutes and let the temp gauge come all the way up, the hesitation goes away. The high idle is also much more persistent when the weather is cold. Eventually it will settle down, but it takes a lot longer.

I'm thinking the problem is pretty much all in the choke. The thing is, it's almost like 2 contradicting symptoms. The hesitation feels like there is not enough choke, and the high idle makes it seem like the cold weather is making it take too long to heat up the choke enough to pull it off.

I guess the simple answer would be to just pop the hood and look next time it's really cold and see if the choke has pulled off with the engine completely warmed up, but that's usually not terribly handy to do, and the temps are warming up now. That may be the only answer, but for now I figured I would at least ask and see what you guys thought.

 

Sounds like all your problems are pointing to the choke not working properly. Get the choke set right on that motorcraft and you will think you have fuel injection.

 

I found a PDF online with some better instructions on setting the choke. I went through it's process and right now it seems to be running like a dream, but it was in the 70's yesterday too. I won't know for sure until it gets cold.

 

https://www.ford-trucks.com/forums/8...-answered.html

 

Hmm... very interesting. My truck seems to be missing the hot air tube entirely. I guess my answers might lay in that thread.

 

From what you wrote, I would almost bet on it being the lack of warm air to the carb when cool and humid...

 

I think the choke may indeed have been my problem. I posted on the other thread how I have rigged up the hot air choke and it seems to be working now. It was in the high 30's, low 40's this morning and it drove absolutely great, it never missed or stumbled at all.

Today I grabbed my mileage log book and decided to run the numbers and found some interesting info.

When I first bought the truck the hot air choke was gone and the electric cap was rotated to the point that the choke never applied at all. I drove it from Bristol to Crossville on the interstate and got 13.77 MPG. Two days later my wife and I went to Fall Creek Falls and the next day I filled the tank up and found that I had got 17.91 MPG! That's not bad at all for an old 3 speed, hell it rivals my '95. Later in the week I drove it back to Bowling Green and when I filled up the tank I got 13.7 MPG. I'm sure the difference is that the Bristol - Crossville and Crossville - Bowling Green trip is mostly interstate driving at 70 MPH, whereas the Fall Creek Falls trip was mostly state highways at 55 MPH.

After I got back home to BG is when I started trying to fix some things. Due to crud in the tank / lines and a non working fuel filter I ended up with crud in the carb. I rebuilt it and then worked on trying to set the choke. From June to November I got gas in the truck 11 times and averaged 11.87 MPG. That doesn't seem TOO terrible if you consider that this is mostly around town stop and go with the occasional 9 mile sprint down the parkway / interstate at 70 MPH. It was pretty cold this winter though, and from December until yesterday I got gas 6 times, the lowest mileage being in December at a whopping 8.35 MPG and highest yesterday at 10.76, average only being 9.4!

When I rebuilt the carb I didn't change the jets or anything, and I haven't touched the idle mixture screws since I re-installed it and initially set them. The only thing that has changed since June has been the temperature at which I have been driving.

Now that the choke is working properly, it is running as good as it has since I've owned it. I have high hopes that my mileage will jump back up closer to where it was when I first got it, and hopefully be more stable in regard to outside temperature.