My truck was acting weird this weekend. Normally after a minute or so of starting and fast idle I can drive no problem. This weekend while it was colder outside, mid 40's, the truck seemed to take much longer to warm up. If I would try to rev it like I normally would it would stutter and want to hesitate. I had to warm it up much longer than normal. It's a 460 with a Carter AFB and normally starts and warms up easily. Am I just going too rich when it's not really warm enough or shall I check my choke adjustments again? How long do you normally need to warm up your truck when it's cold and how does it act if you don't wait. Mines never done this before.

 

I would check the carb adjustments just to be sure they are good (choke, fast idle.etc.) Also it could be the blend of fuel in the tank. They change the fuel blends to cope with temperature.

When I had my '77, I would let the truck run about ten minutes before I drove it when it was really cold (<20°). I would usually just start it up (heater on!) and go back in the house and finish getting ready for work.

 

My truck takes 5 to 10 minutes to warm up in cold weather, and this is bad because my carb is way out of adjustment. It really shouldn't take more than a minute at most to warm up, and even that is kind of long. When the carb is properly adjusted you should be able to start it up kick it down and go.... I personally like to let the truck warm up but it is not a daily driver.
Good luck... sounds a little rich...

Vince

 

From what I have been told from a longtime fuel distributor, methyl alcohol is no longer added to gasoline to prevent carb icing, as most everything is fuel injected now. I find adding a little HEET(de-icer/fuel conditioner) to the fuel has helped tremendously in my old carbureted stuff. My truck used to die at the same stop sign each cool damp morning, one day I hopped out & lifted the hood quick enough to see the sides of the carb iced over. May not be your problem but maybe it will help, we have a lot of humidity year round.

 

At first start up in the mornings.

10 minutes is quite normal for a engine to get to normal operating temperature.

An engine reaching normal operating temperature in one minute or less? I have never seen that, even with a block heater, or in 95 degree heat.


On a properly functioning choke.

On a cold morning, before you start turn the key to the on position, press the gas pedal all the way to the floor. This should close the choke and set the Idle cam to "Fast idle".

Now try to start it. when you first start it, it should open up slightly and be on the fast idle cam. Wait about 10 seconds then kick it down by pressing on the gas pedal.

When you kick it down, the choke should open about half way, and be on the Kick Down Idle cam. As the engine warms up, you can keep "Kicking down" the choke opening it up a little more each time, as the idle works through the notches in the Choke idle cam, until the choke is fully opened, and you reach normal idle speed.

According to my 1973 F-series owners manual, in cold weather operation, you should not drive the truck until the idle reaches normal by kicking down the choke. This may take several attempts (depending on temp), with the idle decreasing in speed each time you kick down, until normal idle speed is reached. This helps ensure heat transfer from the engine to the transmission, so the transmission lubricant isn't gooey or gummy with the cold to prevent damage.

Hope this helps.

 

This is the precise reason I went to a electric assist choke.

Cold air blowing on the choke housing vs slowly warming air in vacuum system going thru choke housing

 

I really wasn't referring to operating temp. I was taking about the first kick down from fast idle... after the first kick down the truck should be ready to go if one wanted to get going. But it would be better on your equipment to let it warm up. My truck has to warm up for at least ten minutes or it will hestiate and sputter when I first hit the gas, unless I really easy into it, but after it is warm the problem goes away. The iceing could be a problem on the really cold mornings, but it is this way even on perfect days of the year. I know the timing is dialed in, so I believe the carb is to blame, and carb's do tend to work themselves out of perfect adjustment from time to time season to season.

Vince

 

On my old truck I had a manual choke. The PO had installed it in place of the electric one. When I started my truck in the morning, I would give the throttle a quick blip while pulling out the chocke. This would set it to fast idle where I would leave for a minute or two. I then pushed the choke open and the truck remained at fast idle till I kicked it down. Worked like a champ.

 

Well you better start

It's the choke setting and it's movement has that has a direct correelation to the fast idle circuit.

It is the flipping of the accelerator linkage that allows the fast idle curcuit/choke linkage to bring the fast idle Down.

It is the action of the coil spring inside the choke housing that coils to deactivate the choke linkage.

Heated vacuum is a slower way to heat the coil to actuate the linkage.

Electrically assisted heated coils in the coil housing actuate the Linkage FASTER bringing the Fast Idle circuit off SOONER.