new truck help.

[gregamorton]

guys I got a clean 78 f150 with 109000 miles on it. The owner took to the same mechanic all its life and thats who I got the truck from. It drives great. interior is like new and the steering is tight. It has a 302 4speed in floor with 3.00 gears out back. I have run half a tank out with b12 in it to try to make it run a little smoother. The carb has just been kited and it has all the original stuff on engine and there is nothing missing. the mechanic put new wires plugs and changed all the fluids also. It is great but it has a small miss at the same speed or hesitation taking off. It has got a little better with the more I drive it but I was curious if there is something besides fuel that would cause this with all the new parts on it. The only thing I can think of is the electronic ignition box is leaking that stuff out like most do. If I bought a new one do yall think it would make a difference on idle and taking off hesitation. Also truck is pumpkin orange with brown interior. crazy looking but great truck. Any help is appreciated.

[gregamorton]

guys this truck has the full factory exhaust and every little factory marking under hood. no oil leaks and power steering power brakes ac. Just exited about my find. Also wondering what kind of fuel mileage yall might get with this setup. Hoping for 15mpg. I have a set of 2.47 gears and 2.75 gears if I dont get the mileage with the 3.00s. the factory muffler has a hole and am going to change the exhaust next week. at the y pipe I was thinking of going up to a 2.25 or 2.5 pipe with a turbo muffler into a singe tail pipe.

[fordman]

usually a hesitation at take off is the accelorator pump in the carb.

[gregamorton]

so more than likely the carb and not the ignition?

[JMcTurnan]

98% of the time it's the carb, at least every time I have run into it. Timing can sometimes do it, but it has to be way f'ed up.

[knightfire83]

Since the carb has been rebuilt, I'll assume that the accelerator pump is working on the carb.

Some Possibilities:
- The accelerator pump actuating rod is in the wrong hole on the pump arm or throttle shaft.
- Carb. idle mixture not adjusted correctly.
- Incorrect ignition timing.
- Non functional vacuum advance on the distributor.
- Vacuum advance connected directly to manifold vacuum and not connected to a ported vacuum source.
- Vacuum leak: Hoses, gaskets, loose intake manifold or carb mounting bolts, or power brake booster internal leak.


At what engine speed does the miss happen at?

[knightfire83]

The accelerator pump has a diaphragm, spring, and a small rubber disc check valve.

Usually the diaphragm will get cracks along the outer edge this results in the pump sucking air instead of fuel, or it will leak fuel out the front of the carb or both.

I've never seen a check valve go bad, suppose it could get gummed up with old gas or parts of it could deteriorate. In this scenario it would not allow the pump to suck in fuel from the float bowl or push out fuel into the venturies.

Another possibility would be that the passages in the carb leading from the pump to the venturies could be blocked, not allowing the accelerator pump to work.

To check the pump operation you need to take off the air cleaner and look down the carb with the choke open. ENGINE OFF. When you move the throttle, if the pump is working, it will shoot a small stream of fuel down around the venturies 1 stream per side. If not repairs are in order.

As far as the settings for the actuator rod, you would have to look at the instructions in a carb. rebuild kit or some other kind of manual. Keith was working on scanning allot of instruction sheets that comes with carb. kits, perhaps someone could point you to the correct location for that information here on Fordification.

[gregamorton]

guys since I put in the b12 and a fresh tank of gas it is running better. The timing must be right on because it start perfect and shuts down perfect. It is running quite a bit better but when you let out the clutch easy in 2nd it wants to try to die unless you give it a little gas. I have always had bigblocks and they would just in gauge in gear and go. Maybe the 3.00 gears and 302 is just not as powerfull and tries to strain. In compound it doesn't try to die. It runs real well at higher rpm and seems not to stutter at all.

[ezernut9mm]

guys since I put in the b12 and a fresh tank of gas it is running better. The timing must be right on because it start perfect and shuts down perfect. It is running quite a bit better but when you let out the clutch easy in 2nd it wants to try to die unless you give it a little gas. I have always had bigblocks and they would just in gauge in gear and go. Maybe the 3.00 gears and 302 is just not as powerfull and tries to strain. In compound it doesn't try to die. It runs real well at higher rpm and seems not to stutter at all.

i just boought my first 302 powered truck and it does not have that off idle torque like what i'm used to in the fe's or 385 series engines. you will have to gas it from a stop in second gear. plus those 3.00 gears are a little tall. probably gets ok gas mileage on the highway though. congrats on the new truck, got any pics?

[Skifu]

Hey Man,
Gregamorton,Post us a pic of your truck,Id like to see how orange with brown interior looks.
Ive had the hesitation problem before,and all It was on mine was a carbon deposit on the number 2 spark plug,I cleaned it with a slice of sand paper,and wire brush,sprayed it off with some carb cleaner,re-installed it,and that was it,back to smooth as glass idle.The contact was almost fouled shut,from a plug that had been in for 4 years or so,from what I could gather,these engines run so good for so long,that no one checks nothing untill it starts acting up.

[gregamorton]

well guys got a new muffler on the truck so when I got to the carb shop they could hear whats going on. WE messed with lots of stuff but come to this conclusion.
So for found one wire to coil bad. The vacuum advance was not working and the carb was leaned out to much. This weekend I will take off cap and sand all metal points and change to a new cap. I will check all plugs to see what I have going on there and just tinker. After what we did today it runs a lot better without to much hesitation at all. There is a small miss you can hear at the tail pipe but its nothing like before. We also added a electric choke. I will get a video and some pics later for yall to see the truck.

[gregamorton]

If there wasn't rust in the driverside fender this truck would be awesome! Solid no rust under the floor pans and frame is solid. Cand figure out how the rust would have started in the fender like it did.

[ezernut9mm]

that does look like a clean old truck. i'd guess the rust started with some spilled brake fluid and once the paint was all ate up mother nature did her thing.