Bronco running rich

[triracer67]

New to me bronco, running very rich, exhaust wreaks of gas, won’t idle. Purchased the bronco a few weeks ago, I’ll do my best to tell you what I know. Stock 289, points, 2-barrel holley manual choke with 1” spacer. I replaced the points, capacitor, plugs, wires, rebuilt carb, just last week. After changing everything, it still runs rich, doesn’t want to idle below 1000 rpm’s, it does idle at about 1500, and revs fine. I don’t know timing, it looks like there is no harmonic balancer. I’ve messed with timing and timing light, ended up back at original timing. I’ve set the air fuel at 1/2 turn, still runs rich. All vacuum ports are plugged. Manual choke is wide open. It starts right up, seemingly runs good, won’t idle, just dies. I’ve adjusted idle up and down, can’t get it to sell below 1500 without dying. Starts right back up. New fuel filter shows new gas(clean) is running into carb. Stock exhaust manifolds, small stock exhaust.

 

[triracer67]

Timing pointer

 

[Brush Hog]

Might actually be running lean. I had gas/exhaust smell and popping in exhaust on deceleration. Thought it was rich but was actually running lean. That and timing was a few degrees off.

 

[triracer67]

Another question…are there timing marks? Do I need to wire wheel that and find marks? I have timing light…

 

[Wild horse 75]

Definitely need to check the timing. You should also check for vacuum leaks. And as mentioned lean can cause symptoms similar to rich. Also do you have the vacuum advanced hooked up? Do you know if the mechanical advance is free in the distributor? do you know what curve is in the distributor?

 

[triracer67]

Vacuum advance is hooked up. I have a few things to check in the am…

 

[DirtDonk]

Yes, there should be marks. Just roll the engine over by hand until you find them.
Scrape or sand everything clean if you need to, but the paint should’ve kept it pretty rust free, and it looks like it’s pretty clean.
If there are no marks that would be a bummer and very unusual. But you can fix that ultimately by finding top dead center, using one of the normal methods, then put timing tape around the edge of the damper ring. Your future tuneups will appreciate that!
Your original one could have slipped also, but you’d have to inspect closely for that.

I see a breather on the drivers valve cover. Is there a PCV valve on the other? You need for it to run clean, but you might also need that to run properly if the carburetor is jetted for it.

Find out why it won’t idle down. Either you have a big vacuum leak, or the choke linkage is stuck.
Even if it’s manual and pushed all the way off, you need to look behind there to make sure that the idle linkage has dropped. Y
ou’ve already stated you verified the choke plate is open, but follow it down and make sure that the fast idle cam is not touching the fast idle screw.

Maybe that’s not what you’re describing though in that perhaps you can turn your idle speed screw down to the point where it just dies?
Or will it just not go below 1000?

 

[triracer67]

Update! Wired wheeled the balancer, timed at between 6-8 degrees. So, it is correct. Once running I sprayed all around base of carb and no increases are decreases in idle. All vacuum ports have caps. I found that 2/3 choke will keep the motor running at about 1k, revs fine, doesn’t stink a lot. Adjusted the idle, and air fuel to make like normal idle. So, thoughts? Paul, the choke/idle link on pax side is not stuck, it kind of moves around 1/4”. In other words, I don’t think it is stuck. What should it do? I set the air fuel screws at about 2 1/2 turns.

 

[DirtDonk]

There is never a set value for the number of turns on the idle air screws.
The recommendations they give you in the instructions are simply a basic starting point that is known to work as a starting point.
You get the truck idling, you set the timing and dwell (if it’s got points) and then you turn the screws in and out to achieve the smoothest idle.
Then you adjust the idle speed, then adjust the air. Then you check the timing again. Then you adjust the idle speed to where you want it. Then you check idle air screws again.

They do not have to be exactly the same on each side. Every carburetor and engine is a little different, so you may have 2 1/4 turns on one side, and 2 1/8 on the other side.
Just as examples.