1985 Bronco 2 Duraspark Distributor with HEI Conversion

[ford4wd08]

Yes, the fitting next to the pull down.

Plug it it is then....

Thought it was weird and had never seen it before.

 

[19Walt93]

It was called a hot idle compensator and it was useless.

 

[ford4wd08]

It was called a hot idle compensator and it was useless.

From a little more reading it appears that it was a controlled vacuum leak to make the engine idle higher at a certain temperature or if the A/C was running.

 

[ford4wd08]

I had to help one of my wife's co-workers with their brakes yesterday, but I was able to get the distributor in and rebuild my new carb, and it runs!

I think the distributor needs to move one tooth, so I'll work on all that today and clean up all the vacuum lines.

On a '85 model the HEI is definitely the way to go, I did nothing to the stock wiring harness other than add a wire to the positive and negative leads on the coil. I left everything else the same. I haven't even touched the computer yet, just unplugged and the sensors and vacuum lines.

 

[ford4wd08]

Got sick Sunday (running a fever) and then I dropped the distributor hold down to the depths of hell of the engine bay and transmission.

Still haven't found it.... Luckily Ebay has some chrome ones for the V8's that fit... (had to replace the bolt metric vs SAE, but the hold down was the same).

It runs! The mechanical advance really lets this thing spool up quick. I don't remember it doing that with the TFI.

Here is the best part. I didn't have to do any of the special splicing required for the '85 to use the duraspark. All I had to do was splice in a wire to the + side of the - of the coil and run it to the HEI, then run wires to the distributor. I left the rest of the plugs in tact and I have been removing wires from them as I go.

All gauges work and everything inside works too.

So I have a couple of questions... Where should I hook up the vacuum advance? Manifold or Port? What all vacuum lines do I need on the engine and where do I route them? I have some on the carb I need to figure out. I left the main tree behind the carb alone that is on manifold vacuum. It still has the brake booster and all hooked up.

I also need to figure out where to hook up the PCV.

My new carb has a hot air assist electric choke. I am actually thinking about keeping it and using it. I bought a doorman kit to try and hook it up. I notice it pull vacuum when running too.

I'm sure I'll have more questions, but here is a little teaser video for now.

Still have to do trans pressure switch and clean up wiring and find a place to hook into electric choke.

 

[ford4wd08]

Also snapped a couple of pics of my HEI mount on the fender and my EGR block off plate.

 

[ford4wd08]

Found this on the web.

https://bangshift.com/forum/forum/bangshift/tech-section/32851-ported-vs-manifold-vacuum-advance

Explanation makes sense. Think I'll hook up my vacuum advance to manifold vacuum.

 

[franklin2]

I just did my swap and I hooked the distributor to a ported vacuum source. You can try it either way, but with a automatic you may find the engine idles really high with the dist on manifold vacuum. Of course if it does you can turn the idle back, but then when you put it in drive, the engine may stall. So then you start turning the idle up, you may even find a tree to put the bumper against and leave it in drive and adjust the idle that way. Then when you are all done you put it in park and the engine starts racing at high rpms again.

If you run into those idle speed problems, the ported vacuum port will eliminate that. You need to set your idle down so there is no vacuum on the ported source unless you rev the engine. Then when you use that, you can set the idle and the idle speed is nice and constant when you go from park to drive.

I am still using the feedback carb on mine. It runs really good, too good to mess with. I am getting about 17 mpg with just the solenoid unplugged. The feedback carbs did not use a ported vacuum source, the computer controlled all that. But luckily I found a factory block off plug on the very front driver's side of the carb that was not being used, and it ended up being a ported vacuum port. It was a little difficult getting their plastic cap off, but once I did that I had a place to put my distributor vacuum line.

 

[franklin2]

Found this on the web.

https://bangshift.com/forum/forum/bangshift/tech-section/32851-ported-vs-manifold-vacuum-advance

Explanation makes sense. Think I'll hook up my vacuum advance to manifold vacuum.

P.S. I read your link above. A good explanation of how it works. But the key here is how that particular distributor you have ( I probably have the same one, 1979 mustang II?) was originally setup. If you re-read the article, you will see he mentions when they came out with ported vacuum, they recalibrated the distributor curve for more advance. So sometimes unless you get into the distributor and start modifying it, you have to stick with how it was hooked up originally for it to work correctly. Hooking a dist curved for ported vacuum use to manifold vacuum, may be where I am getting the high idle problems. See what you get when you hook yours up, there is no harm in experimenting with it.

 

[ford4wd08]

Yes I agree/know some are manifold vs ported for the vacuum. Like you said I'll experiment with it tomorrow.

I plan on getting it out and driving it tomorrow. Just have to clean up the wiring and finish the trans stuff.

 

[ford4wd08]

Wow, what a difference! Drove the bronco around for a minute today. It's like a hole other engine under the hood!

I need to finish up a couple of vacuum hook ups and the get to the pressure switch on the trans.

Is any vacuum port on the carb a ported vacuum source?

Dizzy didn't like manifold vacuum, so I need to find ported vacuum for it.

The HEI definitely made this an even easier swap. Just add two wires to existing harness and make a harness for the dizzy. No chasing stock wires to splice any together, and I got to keep the TFI coil.

I do need another choke pull off. The one I have is shot.

I also need to remove the smog pump. Its unhooked, but I need to pick up my new belts for it first.

 

[franklin2]

On my electronic carb, on the front driver's side corner, there was a vacuum port there. But it was plugged off with a different type of cap. It wasn't rubber, it was plastic and it was very difficult to get off. I tried this port after I got the cap off and it turned out to be a ported vacuum source, I hooked it up to the dist and it works great.

Some other notes on this engine lobotomy; I was able to unwind and pull all the old computer wiring out, carefully keeping the oil, temperature, and evap solenoid vent wires on the engine. Pulled the computer and all that stuff on the pass side fender off.

You can take the electric choke connection, and hook it to the white/black wire coming from the back of the alternator. That wire comes from the back of the alternator and makes it's way over to the driver's side where the regulator is located. You can intercept this wire and tee into it, and run a new wire to the electric choke to power it. The electric choke on the electronic carbs is fully electric and is designed for 12v, but the 7 or so volts that comes from the alternator still makes it work. Mine works fine like this. Having it hooked to the alternator keeps the choke from warming up till the engine is actually running.

The evap system; At first I left the large hose port on top of the carb open (the bowl vent) and the charcoal canister open. Everything ran fine, except I would get a pretty strong gas smell sometimes. The original computer system controlled this system with a solenoid. There are actually two solenoids in this system. If you find your old hose system, you can hook the hose back onto the bowl vent, and that runs though some sort of check or something and then a solenoid. You can hook this solenoid back up, you should have a connector in the harness left over for it. It just goes to key-on power. Key off, the solenoid is open and fumes from the carb go to the canister. Key on the solenoid is closed, fumes go down into the engine when it's running.

There is then a tee in the line, and then another solenoid. This is the problem, no computer means this solenoid is not going to work. What I did was take this solenoid out, and plugged in one of the very small colored plastic vacuum lines I had left over. I then ran this around the back of the carb and plugged it in the original purge port, which is the port on the drivers side rear corner of the carb. This line is very small, so it's just a small vacuum leak. it doesn't seem to affect the performance of the engine. The original solenoid used a larger vacuum line, and it only purged the evap system when the engine was ready for it. Now I do not have a gas smell anymore.

 

[Lefty]

Ended up getting the distributor from O'rielly, Advanced showed it online as in stock, but couldn't order it.

I sourced all the rest from Rock Auto since I couldn't find any coupons to match their pricing including shipping online.

Also one of our members has an a Pinto 2.8 Carb, I'm going to get it from him and hopefully have this rig running right!

Years ago I had a 2.8. I put a 2 barrel Holly on it and got a little more power.