So, I have a 66 F-100 with a 390 motor added (and a C6 transmission). An older truck like this is a new experience for me. When I pull the choke 1/2 way, turn the key, and give it a little gas it starts right up, but I have to keep my foot on the gas for a few minutes, or it will stall. It will then stall if I put it into reverse or drive unless I let it warm up a good 7 minutes or so in the summer. Once it's fully warmed up - the temp guage moves up a bit then it drives fine without stalling. I have stalled, but once it warms up I am usually good to go. Is this normal?? Thanks in advance. Oh, and before I start moving I push the choke back in most of the way. Drive a little bit then push the choke all the way back in. Thanks.

 

Wow. It's just that time gets away. We have more than a generation that has never driven a carburated vehicle. Remember you are the brain for the engine. EFI vehicles rev and feather the throttle automatically to warm it up. You have to make all those adjustments manually in a 66. There is a learning curve in feathering the throttle on a cold vehicle to avoid stalls.

With that said, It does sound like your truck needs some minor adjustment. Maybe a tune up, maybe the timing or carburetor needs some fine tuning.

They all need to warm up for a few moments before being driven but 7 minutes sounds excessive to me especially in the summer.

 

Mark, I think some tinkering is needed. I have had manual chokes that you had to pull part way and leave for a bit. I have come home after driving all day and found it still out. Could be the fuel pump needs replacing, fuel filters need replacing.

I have found a local shop near me that I take my current 66 with a Holley electric choke to for the tinkering needed.

You shouldn't need that much attention in the summer months.


John

 

Thank you!

 

If I have not done so let me take the opportunity to welcome you to FTE!!

Agree with comments, since there's a possibility it is a carburetor issue suggest place truck on level ground and remove fuel level sight screw, fuel should be just below the sight screw threads. I have found with my 390 beast it's important the tune-up components are well maintained and occasionally check the settings. Pull a couple of spark plugs both front and rear on each bank to determine If possibly running too cold or hot; if so adjust mixture accordingly keeping in mind any change in fuel mixture requires going back and reset the timing. I run around 12 degree's BTC and since I have a carb where the vac advance operates off secondary vacuum I do not block off the vacuum line when adjusting the timing or fuel mixture. Anyhow, had an urge to chime in.

 

1st) Some manual choke carbs have a fast idle cam that works when the choke is on. Have someone operate the choke for you and see if you can see it. They are usually adjustable and you can get the engine to run a little faster while on choke. This is a normal feature on automatic trans vehicles.
2nd) You may need to run more than 1/2 choke when she is cold. Not unusual for a "cold blooded" engine to need a lot of choke to run cold. Any carb with an electric choke will go to full choke when the engine is cold. Try running more choke. Then ease it off as the engine warms up.

Choke that thing! LOL

 

7 minuets to warm up is a bit much. Today it was about 90 degrees here. I did not pull the choke, pumped the gas 2 times, she fired right up. It was fully warm in about 15 seconds. Winter here in the morning is usually around 35 degrees, It takes mine about 3 or 4 mins to fully warm up. But it used to take a bit longer before I tuned it up. Maybe a tune up would help, but that's just a guess.

 

Welcome to fte!

You definitely have a slight issue.. I pump my pedal 3 times and it fires before you can count to two.. Also runs fine (cold start) with no choke in this Alabama heat

 

At some point may want to consider swapping points out for Electronic Ignition, suggest 1st resolve current issue and may want to consider at later date??

 

Thanks to everyone for the input. I actually do have an electronic ignition, no points.

There was one small detail that I did not disclose.

I just bought the truck and I doubt it was driven very often before I bought it. So, my fist plan is to make sure the carb is nice and clean and the fuel fresh.

I just changed the fuel filter which was well needed. Tonight I emptied almost a whole can of B12 into the bowl of the carb while running and revving the engine. I am currently on my 2nd full tank of gas and put a can of Sea Foam into this 3/4 tank I currently have. I plan on treating all my fuel with some sta-bil as I do not plan to drive this truck on a daily basis.

Things seem to have gotten a bit better: it starts right up, but I still have to warm up for a while or it'll stall when I put it in gear or let go of the gas too soon. I do notice a little stuttering or hesitation on acceleration while driving here or there.

If things do not change much more once I've given the sea foam a chance to work, maybe another can of carb cleaner spray too then I'll start playing with the carb settings. I'll probably need the help of a more experienced mechanic for that though. I don't want to screw things up worse.

 

And another thing: The truck would stall out while driving (before being warmed up), but this seems to be happening less, if at all once I get driving. I think one of my problems is that I either had some old fuel that went bad in the tank, or the carb is a little gummed up . . . we'll see.

Maybe I should just take the carb off and dip it.

 

Things improved when I changed the plugs and wires, but now that I rebuilt the carb it runs perfectly. I am going to borrow a light to check the timing just to be sure, but the carb rebuild was a game changer. Does not need to warm up more than 30 seconds or so and no more stalling. Thanks.