71 F100 390ci

[wyngnut55]

I have a 71 F100 Ranger XLT that I have done a frame off restoration. I was looking for this specific truck to do this project, bought it in Tuscon AZ basicly a basket case. I was able to get the engine running and drive it a few miles before I tore it apart. The engine did not smoke, compression is good and seems solid with no noises.
The truck is back together, looks great and loves the freeway. I replaced freeze plugs on the engine, cleaned it up and put it back in thinking I could pull it again fairly easy if the engine had major problems. I have spent a lot of time on this thing but don't have too much money invested in it. ($9000 total)
The issue is, Its takes 10 minutes to warm up, after it does I can't get it to idle smooth and it dies at stop signs sometimes. Its has a 390ci with a Motorcraft 2 barrel carb that ( by the wear on the screws) looks like its been taken apart a few times. I took it apart, cleaned out the dirt, cleaned all jets and orifices and replaced mounting gaskets.
Im thinking of spending the $1500 on a throttle body fuel injection system. I put a Howell throttle body on a 84 Jeep CJ, 258ci 6 cyl once, it ran great and got much better mpg afterward.
I checked for vacuume leaks and as far as I know it doesn't have any.
My questions. Is going to fuel injection worth it or can I spend the $300 or $400 on a new carb and make this thing run good?
Has anyone out there installed a fuel injection retrofit kit on a big block?

[sargentrs]

Choke working as it should? An improperly working choke can make you think you need a new carb? Ive bought 2 Autolite 2100's and a Holley 1 bbl from these guys http://www.guaranteedcarburetors.com Had them add electric chokes on the 2100's and all have been bolt on and go with only minimal fine tuning.

[6Delta]

10 minutes is a lot. What thermostat did you use and is it working right? Does the heater put out hot air and if so how soon? The 2100 is not a great carb. However is decent and can be made to run very well if you check a few things before you rebuild it. First check the shaft with the butterflies both open and closed. Also check for play both back and forth as well as up and down. (I have had rebuilt carbs out of the box with significant slop at the throttle shaft and sent them back.)

You said the idle screws showed wear. Were they smooth down to the end or did they have grooves on them. Many times they have been screwed in to hard and bottomed out damaging both the screw and its seat. Add normal (and abnormal wear) over time and the crappy gas out there that gets left in them, and some carbs need a lot of work of work to get it to run and idle right. Even when reworked the choke on a 2100 can cause problems if it is not right. Making sure the choke comes off when hot is important. (I like a manual choke with a cable I can set.) The other thing I see most often is inadequate cleaning prior to the rebuild parts being used. I am a firm believer in soaking the carb and its parts in cleaner overnight. It is very hard to clean a gummed up carb completely with spray cleaner. A carb that has been not been used regularly has varnish and gunk in places that just doesn't get removed with a spray can. Soak it completely for at least 12 hours, rinse it with water and blow it out with high pressure air. I usually get a rebuild kit from NAPA but have started to notice they are getting skimpy on parts compared to 10+ years ago.

That said you can get a small Holley that would wake up that rebuilt 390. They will get good mileage (depending on your rear end gears) and be very dependable. Plus they are a lot cheaper than EFI.

The engine dying at a stop can be related to a lot of things especially on a fresh engine. You do have to rule out one thing at a time and the 2100 is a good place to start. I have several carbs sitting on the shelf and several will need to be gone through before I can use them just from baking in the garage in a box. Good luck and keep us informed about that ride.