This truck has sat around alot since a oil pump replacement and wasn't running good at all. So I replaced the stock electronic choke Holley four barrel with a new stock replacement (from Autozone). It ran decent for awhile.
We did not reuse the smog, good or bad. All of the sudden it runs bad again. Don't know if something from the smog equipment should be rehooked up for proper engine performance.
The motor was running really rich, in the cold you could see rings of raw fuel rising from the tail pipe and if you reved the motor black smoke would roll.
So I turned the air/fuel mixture screws to the right until they stopped then turned them left l.5 turns and it seemed to have leaned out the motor well. It ran good for a few days. Now it wont idle under 2,000 rpm.
The only thing I can see that might be concerning is that the brand new carb is leaking fuel from the accelerator pump diaphram gasket which is at the bottom of the carb. Also at idle the back two "barrels" of the carb are dripping fuel, is this normal. Engine has been getting about 4-5mpg! help.
I have replaced accelerator pump diaphram gaskets before and hope that replacement will help. Is it possible that too much fuel is leaking out and too much air is coming in through this leaky gasket or another yet unfound leak.
I adjusted the choke, and it is hard to start as if the carb is dry from leaking. Any ideas that could straighten me out are appreciated.

 

It sounds like the float is either out of adjustment, level set too high. or it is hanging up and not shutting off the needle and seat. Good luck.

 

this is kind of the same problem I'm having with an 86 f250 351w ho. This truck had recent rebuild. bored .030" over 10.5:1 cr, summit 3/4 cam (whatever that is) motorcraft (holley) carb with elect. choke and idle compensator, but no computer controls. The closest thing to a computer in this truck (at least as far as I know) is the ignition control module. We yanked the carb and threw on a edelbrock 1405 w/ manual choke. The previous owner replaced the entire ignition system except the coil. In order to throw the carb on, we had to modify the thermostatic choke on the intake, because the block off plate I ordered and waited for didn't fit!!! We yanked the egr stuff next because it seemed like a major vac. leak and I was running out of possible causes. I have since replaced the intake gaskets after finding a vac. leak by spraying starting fluid (lightly) around the manifold. It is my understanding that they commonly leak in the back and I found out why when I changed mine. I didn't want to mess with the distributor and left it in place, but whew... that is one heavy intake manifold, and to manuever it around the distributer and all the linkage brakets and etc. with sealant on it flawlessly would be impossible. That isn't how I did mine though. I put the gaskets and sealant on the heads/ valley first, and then just lowered the clean dry intake into place. But this did not correct problem either. I have replaced every vac. line, removed emmisions,removed every vac. port not critical to the running of the engine and sealed with threaded plugs. All this trial and error cost me a starter which I replaced with a jegs high torque starter and then I replaced my cables with custom made 4 guage cables wrapped with wire loom and brass connectors. Now it cranks likes a champ, but the driveability problem remains.

 

I found the summit cam that's in this truck in the catalog which says up to `84. Truck is a `86. Not sure what difference that makes. This truck also has a cloyes timing set. In summit, the cloyes timing set does not specify differences for different years, but the "summit" brand timing set specifies up to 84, and a different one for 85-87. Again, not sure what difference that makes. Then I thought, if there is a difference in the cams for different years and a difference in the timing sets for different years, there might be a difference in ignition control modules for different years too (this is also brand new on the truck, as is the entire ignition system except the coil. Anyway, if there are differences in all three of these parts for different years, who knows what combination I have and if its compatible and if I'll ever get this thing figured out. If you get any hot tips let me know, I will do likewise. Good luck to you. Lord knows I need some too, I'm new to Fords.

 

I think you guys might be having the same problem I did with the year differences. My bronco is a 1987 and I found out that 87 was a split year on carbs vs. fuel injection.The carb models were flat tappet cams,the fuelies were rollers,hence,the cam gear differences .A summit salesman squared me up on that deal when I ordered my engine kit. Hope this helps a little.

 

Sounds to me like you need to tighten up the screws in the carb. Did you install a NEW fuel filter?

 

i had the same problem on my 87 bronco so I replaced the holly stock carb and put a edelbrock on and it made it better. I have searched for info about the holly stock one and have heard that the are only good strait from the factory but if you rebuild them they work good for a short while and then start leeking gas from every where. some people call the the "holly bomb".

 

If it were mine I'd get and edel RPM manifold and a q-jet....

 

I had similar problems, ended up swapping in a "new" Holley 4bbl. In the process we discovered that the gasket for the carb was the wrong one. It didn't have 4 distinct holes, but a cut-out allowing the gas to flow between them. After fixing this, we discovered a whole bunch of vacuum leaks. Ended up putting on a new manifold and doing a complete vacuum-ectomy on the engine which cleared up this particular problem.

Now we are working on the lack of oil pressure at idle....

 

the only difference between a roller and a non roller dist is that the roller dist. has a steel gear!

 

Have the same engine in my 86. Replaced manifold with Edelebrock. Replaced carb with aftermarket Holley. Stock carb has no adjustments for jetting. They are also notorious for warped metering blocks. Might try a new holley. I know several of the people have ran the edelbrock, but my stock linkage wouldn't hook up and one of the components on the drivers side of the manifold wouldn't clear. Ran great up until a month ago when I believe I lost some valves/cylinders (need to do that compression test, but bought used motor to rebuild anyway. Any excuse to get a stroker motor in there.

You might want to make sure the power valve gasket hasn't given out.