Bronco Build questions
 

1986 Bronco 300 six, 4 spd T170, 8.8 3.08 rear end Dana 44 Front. At any rate been cruising the Search forum alot and havent gotten all the anwsers i need. I have a offenhauser intake and duel exaust sitting in the box that i want to install, So being it will be a woods rig i was thinking motorcraft 2100 Carb ( Im new to carbs so not sure what to really do) But i keep reading i need to convert to a duraspark II system and change my ignition? Details please? I would love to eliminate the Smog, egr, Etc and make this as simple as possible as im tired of broke down vehicles due to sensors and wiring BS. I have a set of 31x10.5R15 BFG all terrains ill be putting on, Im redoing all brake lines and brakes upgrading suspension to a heavier suspension, Replacing fuel pump and tank, All vaccum lines etc.. you get the idea. I just dont know how to remove the smog stuff and still have the vehicle run properly. I see one O2 sensor right next to the manifold and 2 cats behind it. I plan on doing 2.5" exaust all the way back So details on the ignition and smog/egr removal and best way to install the 2100 carb? any additional parts i will need? or being its a ford carb is it fairly close to plug and play? Thanks

My grain of salt regarding EFI: If you have it, leave it, it's rugged and it works.

If you're set on going carbed, you can basically remove everything emission-related, the EGR inlet/outlet will need to get plugged, the smog pump can be gutted and used as a pulley or removed/bipassed and the belt replaced with a shorter one (depends on the belt routing, but I think yours uses several belts so it should be easier), for all I know you can remove the ECM since there will be nothing else to control, I would protect the plug from the weather anyway. I'm sure there are more steps to it, but that's all that comes to mind.

So i also have a set of EFI exaust manifolds, Which walker Y pipe is everyone using for that? Part number?

The 302 was the only motor that was EFI in '86. All the others were still carb'd.

So far, it wounds like you have a good game plan.

Which Offenhauser intake do you have? If it is a C style (one big open hole for the carb), then yes, you can use a Motorcraft 2100, which from everything I've heard is a simple and reliable carb. If you have the Offenhauser DP (four individual holes) then you must use a four barrel carburetor. In my experience, setting up the secondaries on a four barrel is the easy part, so a 2bb and 4bbl carb have the same level of difficulty to set up.

Yes, you need to change your ignition. The 86 used a computer controlled ignition and electronically controlled carburetor. ALL of it needs to be working properly to function, so if you do something like remove the carburetor, then it'll shut down and run in LIMP mode and your timing won't advance.

For the DuraSpark II, you will need an ignition module (you should already have holes on the driver's side wheel well for mounting it), a DSII distributor, coil, and then the wiring harness. The harness can be purchased new online, or you can dig one out of a junk yard. It's all just plug and play and will all go right in like it was made for it. I did a swap to a DuraSpark II ignition on my '84 (also computer controlled) and it took about 30 minutes. Most of the time was spent just yanking the old stuff out. You'll be amazed at just how much less is under the hood.

There is also a computer underneath the dash behind the steering wheel. It can go too. As well as that massive chunk of wires going through the firewall to the computer can go, and you can get a delete plug to close up the hole.

Now, I've heard off-and-on that the '86 isn't as plug-and-play as the '84 and '85, but I've never been able to confirm it. Just something to consider. I've never heard it stopping anyone, but it's something you may run into.

Another option is just to buy a single wire, HEI style ignition and run that. You won't have to worry about any wiring except a 12v key on source. It is the ENTIRE ignition, so you won't have to worry about anything else. Performance Distributors used to be the only one that made one, but now Summit has their own version as well.

https://www.summitracing.com/parts/d...view/make/ford

https://www.summitracing.com/parts/s...view/make/ford

As far as the emissions stuff, you can take it all out. You can't use any of it with the EFI manifolds anyway since it's all designed to tie in with the stock 1bbl manifold. The EGR, smog pump, etc. can all go. (I would, however, recommend a 2.5" catalytic converter, even if you don't require it. They do a lot of good and have very little, if any, detriment to performance).


Hope that helps!

that helps alot so which Y pipe will I need for the efi heads? Also title says 86 but it's actually an 84 according to the door sticker. I also have a offy C intake.

So with converting to Duraspark II im having some confusion with what to do with one of the plugs? I have off the Ignition module one round plug and off the harness one square plug that i dont know where to put anywhere...But here is progress so far, Also do i need to run any wires from the coil to starter solenoid? or? Also when i put in the new distributor what do i check timing off of? the Stamped mark in the timing chain cover or the stamped steel sheet with timing marks on the opposite side?

So out of my module i have a red and white wire, The factory harness plug has a white a cream and a red? but they fit like a charm, The DSII harness has a square gray plug with 3 wires the factory harness has a 4 wire 4 prong round plug..can i get a wiring diagram of what that 4 prong round plug is? That way i can splice the old round plug back into the dsII harness, Also the dsII harness does not have a tach wire but i salvaged my old one out..So how do i make that work? Where do i run the single green wire too now, Also the DSII harness has 2 oil pressure sending unit wires but i dont see any wires for the Coolent temp sender which on my engine is a Black and green wire out of a plug on the thermostat housing. So where do i splice that into for proper readings? Thanks!! Hoping to get this running by next week.

Hi Gunnerboy, looks like things are moving along pretty well. :D

Okay, cool. That'll make the job nice and easy. Also, the Offy C intake will make it so you can use any carb you like.
On my build, I used the Walker 45166. It looks like it's getting a little more difficult to find, but Autozone still has it on their site.

Walker Exhaust Pipe 45166 - Read Reviews on Walker #45166

Summit lists it as: "Not available". :-huh

If you get it, just be sure to use an extension and a grinding burr and clean out the rear hole. They don't always cut it open all the way. It took about 30 minutes on mine but was well worth it.

To be honest, I've never seen that square plug before. The plugs are always matched, so you can't put the wrong plug in the wrong port It's usually very straightforward.
Did you get the harness off of a truck with an I6 or a V8? I've heard the wiring harness is the same, but maybe not? There are some wiring diagrams floating around, so maybe one of those can tell you which wire goes to what. Try some searches and see what pulls up.

As for the coil, no, the starter doesn't have anything to do with the ignition. The starter spins the engine when you turn the key all the way, and the ignition simply detects when the engine is spinning (as long as it has power). They're independent of each other.

The best way to find your timing mark is to pull the #1 spark plug and then rotate the engine until the piston comes up to the highest position. Then, look at your timing marks and see. On some balancers, you'll have a timing mark for both the timing cover and the stamped mark on the passenger side. If so, use the timing cover. It's much easier to see and you can adjust the distributor and look at it at the same time. (Also, there's no timing chain, it's gear to gear).

See if any of these diagrams help:

https://www.google.com/search?q=dura...w=1920&bih=974

As for the tach, that's built in. If you already have a stock tach, you should be able to just plug it in and away it goes. I've never had to run a separate wire for it as it's built in. Normally, it goes to the negative post on the coil.

As for the two long wires. The shorter one goes to the oil pressure sender near the rear of the engine on the driver's side. The longer one goes around the back of the engine to the temperature sender underneath the #6 runner on the intake. The temp sender on the thermostat housing won't be used. It's for the computer only (you can remove and plug it).

Hope that helps. :-X22

So i cut off that gray weird connector and wired up the old 4 prong connector using 3 wires that were color coded and matched the older DSII harness...no clue if it will work but worth a try..So on my alternator i have the black stud no longer being used? is that for the electric choke? The rest of the wires and coil are all hooked up so once i finish getting my carb installed which arrives next week ill try firing it up. I got the dist stabbed in but not sure if it was top dead center never felt air blow by on number one but the timing marks were at 10deg and it looked like the lifters were up in the right order..old dist was pointing at number 5 .. so pretty close i think

Hopefully your wiring works out for you. :)

My alternator has a few studs that aren't used. Just hook up the ones you need.
On mine, I hooked my electric choke up to the 7v peg. I used a volt meter while the engine was running to figure out which one it was. Most aftermarket carb installation instructions will tell you to use a 12v source, but I find this opens up the choke much too quickly, especially in cold weather. I found that using the 7v slows it down a bit and really helps.

If you want to double check the distributor, put something light, like a cotton ball, in the hole and rotate the engine clockwise until you can see it puff out. Unless you have a valve that's not closing, it should be a pretty healthy puff of air.

Been almost a year! But that Bronco has the carb done installed and the electrical figured out so far..Got it fired up and timed to the passenger side timing marks Sounds a little rough running but i have no exaust..still need to make a accelerator cable bracket and install exaust, Then ill finish tuning the carb and continue on with the build!

So its running and timed properly , exaust installed and i used a vaccum gauge to try to tune it up..what sort of vaccum reading should i be getting? it was bouncing from 21-23 on the gauge. Still has a occasional miss but i figure its a sticky valve from sitting or the lash needs adjusted due to increase in air and exaust.

21 - 23 is extremely good vacuum. Granted, the closer you are to sea level, the higher it'll be (and you're pretty much at sea level). But, I think that's about as high as any engine's going to get.
How did you set your timing?

As for valve lash, are your rockers adjustable?

Used a timing light..I'm not satisfied with timing still sounds off..but I'm assuming that's because it is due to wear of mileage. Pulled plugs opened up gap to .046 and #3 an #6 were sooty the rest were clean? Those the valves I should address?