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Discussion Starter #1
'86 4.9 inline six. I know this is a good engine, but the convoluted and primitive computer-controlled carb and distributor are driving me nuts. One day it runs great and the next day it won't idle, and it's coughing out smoke from the exhaust AND the carb. I've been troubleshooting this thing to death, but there are so many sensors and valves and solenoids... okay, the EGR valve was bad, and I replaced it, but everything else seems to check out alright.

So. I'm going back to something I can understand: a non-feedback carb from '83 or thereabouts, and a distributor with vacuum advance. On my other six ('79 Jeep CJ7) I have a DUI distributor that I'm very happy with. Expensive, yes, but I'm thinking about it for the Bronco. By the way, the Jeep is dead-reliable, simple and it passes smog with flying colors.

Here's the idea, and please chime in if I'm wrong: what if the computer makes all kinds of decisions on what the engine should be doing, but the engine doesn't listen and doesn't care what the computer says?
 

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The feedback carb setup is an extremely good system when it works. But when it doesn't, it's so old that it can be tough to make it run right again.

Going back to the non-feedback carb setup on the six is a very common, reliable, and easy process. However, from what I've heard, the '86 is different than all the previous years and doesn't quite have the same connection types. Doable, but takes more work. However, I don't have any experience with that, and it's just kinda hear-say. In most cases, it's all just plug and play.

Things you'll need: non-feedback carb, Duraspark II distributor, ignition module, and the wiring harness that plugs it all together. It also has two extra wires that connect to both of the rear sides of the engine (one for the temp and one for the oil sensor). Optionally, you can grab the coil too, since the wiring harness will clip right onto it. Otherwise, you'll have to cut the wiring and put on your own ends.

Lots of stuff that you can remove from the engine bay in that process. You'll be amazed with how much cleaner it'll be (and how much better it'll run.)
 

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Discussion Starter #5
Thanks guys. When I get the parts together I'll report back. I'm sure there will be questions (choke hookup, etc.).

I look forward to it.
 

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Discussion Starter #6
For the distributor I went whole hog. Ordered a DUI from Summit Racing and got it in two days (got a bonus at work and the money burned a hole in my pocket). I put a DUI in my Jeep 4 years ago, and love it.

So today I found top dead center on #1, installed the distributor and wires. The carb I ordered is being built and will ship next Wednesday or Thursday.
 

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I'm working on the same swap. Getting rid of all the wiring associated with the feedback carb really cleans up under hood! Next step for me is adapting a 2150 carb in place of a single bbl. Unfortunately this project has taken a back burner to a couple of other things I have going on, but I'm getting anxious to get back on it. Keep us posted on your progress - you're ahead of me now and I may need some tips to finish mine up! LOL
 

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The DUI is definitely the best way to go. Just kinda pricey (which is why I still don't have one). Hope it works out great.

With the 2150, are you looking to upgrade the intake as well?
 

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Oh yeah! I forgot we'd discussed that idea in your build thread. :D
 

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Discussion Starter #11
Any ideas for a nice clean 12V switched power source? The instructions say to just tap into the fuse panel, but that seems kinda Mickey Mouse.
 

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I used the windshield wiper wire, it worked really well.
 

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Discussion Starter #14
I'm working on the same swap. Getting rid of all the wiring associated with the feedback carb really cleans up under hood! Next step for me is adapting a 2150 carb in place of a single bbl. Unfortunately this project has taken a back burner to a couple of other things I have going on, but I'm getting anxious to get back on it. Keep us posted on your progress - you're ahead of me now and I may need some tips to finish mine up! LOL
It sounds like you're ahead of me (the 2150). I'm going with the 1-barrel just to keep things simple for now. I found a Clifford 4-barrel intake manifold at a swap meet the other day and got all excited until I found out it was for a Chevy. Dang.
 

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Discussion Starter #15
I dug unto it over the weekend. Out came 40 miles of wire and vacuum hoses, along with the three nasty, decrepit solenoids on the valve cover. It turns out that the exhaust was chuffing out through a broken air pump valve that attaches to the egr plate under the carb. I removed it and plugged the hole with a 3/4" pipe plug, which fits perfectly. The problem is getting the old valve out - it took a lot of PB Blaster and a rattle gun to unstick the threads.

I ran the original coil wire (hot in on and run, but not accessory) to a relay, where I get clean 12 volts from the battery side of the starter solenoid. From there I sent a 12-gauge wire to the DUI. The coil wire is the 10-gauge wire going to the 4-prong plug on the driver's fender well - two of those wires continue on to the oil and temp senders.

The carb is scheduled to be delivered this Friday, and I'm ready for it. I'm going to have some questions for you guys when it gets here - I want to keep the EVAP system and possibly the EGR, so I'm going to have to hook 'em up old'school style.
 

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Discussion Starter #16
The new carb has been sitting on my work bench since Friday, and I just now got a chance to install it. Man, this engine runs even better than I expected it to! There is still some tweaking to do - the choke, for example. The old carb didn't have a heat tube, and I need to figure out how to hook one up so the choke disengages fully (it doesn't right now, the wire coming from the alternator is hooked up, but it only turns the choke about 2/3 off when warm). Any ideas? Worst-case scenario, I just go with a manual choke, but I'd rather not if I don't have to.

And I want to keep the EVAP system working. There are two electric solenoids that were run by the computer: one for the canister purge and one for the bowl vent. I'm not sure how to deal with that.
 

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Awesome! That has to feel good.

For the choke, have you tried adjusting it at all?
When the engine's cold, loosen the three screws that hold that black, plastic circular choke housing to the carb. Once they're loose, fully open and close the throttle. Then, rotate the choke housing until the choke butterfly is only open around 1/16" - 1/8". Tighten the 3 screws.
Fully warm up the engine and check to be sure the butterfly opens up all the way.

If it doesn't, there may be something wrong with the choke housing and it needs to be replaced.


As for the EVAP, you may need to head to a junk yard and see how it's implemented on a pre feedback engine. Note all the vacuum line routing. Or, just grab the whole conglomeration of vacuum lines and canisters and bring them home so you can put it on to yours (just be sure to replace the vacuum lines with fresh ones.)

Good luck!
 

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Discussion Starter #18
Thanks, AbandonedBronco. It turns out that my exhaust manifold has a choke stove, so I fabbed up the pipes using 1/4" copper tubing. It works perfectly. This engine runs like a Swiss watch now, and I couldn't be happier.

As for the canister purge: I don't smell gas, so I'll leave it alone for now.

So of course, yesterday I got huge clouds of steam coming out of the dash and my first reaction is not fit for polite company. The heater core was leaking like crazy. Napa had one in stock, luckily, for about $30.00. I put it in with new heater hoses to be on the safe side. I'm happy again.

This rig sat in my construction yard for five years collecting dust, so I'm not surprised by a few problems showing up. Next project is fixing the tailgate window so I can put the top back on before it starts raining. This Tuesday is not looking good.

I have a ton of pics of the progress, I wish I could figure out how to post them.
 

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Nothing quite like resurrecting a neglected vehicle back to its former glory. Been there, done that, have the username. :toothless

The purge canister does 2 things (that I know of): reduces emissions and raises gas mileage. They go hand in hand. By collecting unburnt fuels, or evaporation, it sends it back to the gas tank to be reused, which both doesn't waste fuel, and keeps it from venting to the atmosphere. It isn't a lot (like 1/10 a mpg or something like that), but anything helps.

I love how easy the heater core is to change out on these. 30 - 60 minutes. Quite unlike the Chrysler LeBaron I did, which was about an 8 hour project and required removing an insane amount of things, all the way down to the visors, and dropping the steering column. No thanks....


Check out supermotors.net. They let you create an account and host pictures for free. Then, after they're uploaded, they put the links for each picture on the left so you can drop them into your posts. Works pretty slick!
 

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Thanks, AbandonedBronco. Let's see if this works...

This is what the Bronco barfed out when it was sick:

 
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