Hello I am new to this forum and new to the Bronco's I bought a 81 bronco it looks ok but when you give it alot of gas it pours out black smoke as well as at idle. Also doesn't seem to have alot of power

I changed the cap and rotor and the plugs and wires. Has anyone else had a problem like this? If so could you give me a hint to where I might start

Thanks in advance everyone

 

I'd check the carburator first, but it could be many other things.

 

the carb is probably in need of repairs, bad accel pump, floats out of adjust. vac. leaks in idle circuit

 

I was going to have the carb rebuilt but this is that venture model and it coast like $350

Maybe I can wait a little while it shouldn't hurt anything right ?

Thanks again for your guys help with this

 

The black smoke is usually a sign of a "rich" condition (too much fuel; not enough air). Its most likely a carb adjustment. Dont' let it go too long or you will start fouling plugs and mucking up emissions gear like EGR valve and catalytic converter.

 

Could be a bad choke pulloff. You'd be driving around with the choke on. That'll do it.

 

Do you know how to adjust the needle valves on the carb? Growing up in a carb. era we were all convinced that we could adjust horsepower into the car/truck that way. run them in until cobby and back out 'till smooth, should be two, one on each side at the base of the carb.

 

A word of caution there - be sure to seat those screws GENTLY. Those screws ARE the needle valves. If you are not careful, you will mess up the needle tip on the carb end, and possibly the soft metal of the needle seat inside the carb. Then you will never get it to idle right or properly adjust the mix. So - don't freak out about it, it's not hard, but just be sure to screw them in gently until you feel them seat. Then, as Tex advised you, back them out until the idle evens out and then turn it back in just a tiny hair. You know what type of hair I mean - but this is a family board!

If you are in doubt, the default setting on most carbs is two full turns out for each one. That usually works fine. I usually set it there first and then turn the motor on and fine tune it. There is usually a wide range where it is optimum so you don't have to worry about getting them exact. I usually find the spot on either "side" of the adjustment (ie. when it is too far out, or too far in, you will know when you hit either extreme because it will start to run rough) and then position the screw centered approximately between them.

A couple of hints to make this a lot easier - use a long flexible driver to turn the screws. A bought one for $5 and you can put any bit head on it. Then, as long as the needle valves have a hex head, use a socket tip to turn them so it won't slip off while you are adjusting. If they are round with just a screwdriver head, obviously you will have to use the screwdriver tip but the socket is definitely the way to go if you can. Second, when you are counting the turns out, which is important, turn them one half turn each time. If you try to go all the way around it's hard to figure the turns since it's hard enough to keep an eye on them. I will mark a line on the driver head, or use the letters on it if it has them, and if you are able to use the hex tip then you don't even need to get up in the engine bay, you can stand comfortably back and count the turns from the screwdriver head. I am probably making it sound more difficult then it is, but if you try to climb all up in there and hold a regular screwdriver on the needle valves while the engine is running, not only is that difficult to do on most vehicles as it puts you in a precarious spot, it's also dangerous. I have EFI so I don't do this to my Bronco, but on almost any vehicle that I've ever had to do, if all you have is a screwdriver, you have to get right up in there and try to use the screwdriver on a funky angle so you can't really get it on there nice and straight and it will keep wanting to slide off, all while balancing on the engine, while it is running - with all sorts of hot stuff to burn you, electrical connectors and vacuum hoses to break or knock off, and of course that nice fan would love to eat your hand after you yank it back from being burned by the exhaust manifold that you mistakenly grabbed to steady yourself as your feet were slipping off the bumper. Have you ever tried to power tune and adjust the dwell on a Pontiac 400 with the distributor in the back and up against the firewall? Well the air/fuel mixture adjust reminds me of that, except it's in the front. A simple job to do but a balancing act to get into position for.

Also use a small stepladder or something with rubber feet that won't slip to stand on. If you set all of this stuff up just right, you will be standing comfortably on your stool, while holding the flexible driver at a nice comfortable distance while the socket head is on the adjuster real nice where it won't come if, and you will tell your buddy to turn the motor on and you can stand comfortably while looking at the mark on the driver head to count the turns. The only time that you will have to move is to put the driver on the other screw and finish the adjustment. The other way to do it is, well just think of the opposite of everything that I said. It's a sucky job to do it that way.

I have done something similar to that and sliced the jugular vein on my right wrist clean open - it started spurting immediately and you could see a trail of blood from the engine all the way up to my apartment, the trail had almost no gaps in it, the blood was rushing out that fast. I compressed it with a towel and I thought that I was going to have to call 911, but I was only 20 at the time and luckily my body's clotting mechanism worked well. And the motor was not even running at the time! I bandaged my wound and went out and finished installing the water pump and radiator on my 74 Coupe de Ville. That was over 20 years ago. I'm sure that I would call 911 if it happened to me now.

OK enough of these long posts for me tonight. I gave advice on how not to be ripped off by A/C mechanics, and how not to let your car help you to commit suicide.

JB

 

JB is quite correct and I apologize for not giving the caution on the needle valves, no strong arm, just seat gently. We used to use a coil spring looking flex driver with a socket head that just fit Carter and Motorcraft needles. Course we thought we could outrun the wind on the '69 Mustang in our weekends at the airport crunching cones. We were pretty successful with that car. Kept the 'vettes heads down as well. Then along came Viet Nam, oh well, it was still quite a ride.

 

No problem Tex - I just try to think of myself as a young'un and if there is anything that I can add to help make a hard job easier for them, I will. The air/fuel adjust isn't a hard job pre se, but it's usually hard to get into position for and be able to do it comfortably and properly. I just edited my previous post - you should get a kick out of it and maybe think of some long-ago motoring mishaps. If one person does not get hurt by way of some of my painful experiences, or not ruin a perfectly good part, then my work here is done!

And you gotta love that AvGas! My buddy was a feuler back in the day so we were all screaming around with AvGas in our hot rods. And you mean to say that your 69 Mustang couldn't outrun the wind?

 

If you have the varable venturi carb. with the slides over the barrels the best thing to do with it is throw it in the nearest garbage can and pickup a Motorcraft 2v carb at the junk yard to replace it with. My parents had one on a 79 LTD we couldn't keep it adjusted, it was a happy day when we canned it for a regular carb.

 

Last trip to the past, Ahhh AvGas and small block V-8's growling, we thought we were invincible..... and at least in my memory we were. Of the original 7 of us 2 are left, Viet Nam, a drunk driver, the first Gulf War, and a dumb stupid accident with electricity has pared our numbers down. And I guess every time I work on the truck, wife's SUV, or that Bronco I sold it brought back some of it. Later guys.

 

Tex,

I grew up doing the same stuff to old Chryslers and Cadis. Had a couple of 69 Cadis with 472 under the hood, 400TH tranny out back and a Rochester Q-jet on top. Granted we didn't get the kind of push-you-into-the-seat takeoffs that your Pony would get but man once they were movin'. Had that great big Cadi speedometer that took up half the dashboard and couldn't find the needle it was buried so far down inside the gauge. Drivin' a hearse with a shift kit in the tranny and cross-drilled 427 Corvette pickup tubes in the carb is a trip!

Sorry, I felt the urge to join the trip down memory lane.

 

This place is great Thank you all for your help and I will be adjusting the carb this weekend and I will post the results here. I will also be going wheeling as well this weekend I guess no photo's on this site that's ok I will describe as I can.

Thanks everybody

 

Me too. I still love those old Caddys. I could never understand that when the magazines tested them, they would say that the top speed was 115 or something like that. I've been over 115 in Toyotas. I had Cadillacs with 472's that buried the speedo needle pretty quickly at 120 and got much faster. I also had a 74 Buick Regal with a 455 and a 2.73 rear end. I am sure that I got that car to at least 150. I blew everything off the road in top speed with that car.

And they would leave a patch of rubber longer than a footbal field. That was fun too! I have not burned rubber in a car like that for years and years. My Bronco won't even break the tires loose in the rain.

That's why it makes me wonder when you hear about land speed records for passenger cars at Bonnevile that are like 138 mph or something. Heck, I've been to 125 on a Harley. No helmet, ape hangers, drunk as a skunk, and lived to tell about. I actually used to do that a lot when I was younger. Somebody upstairs must like me. He let me T-Bone a car at 50 mph though.
I don't do that anymore but have no problem cruising all day at 90.