Mystery Distributor/ help an idiot get durasparked

[P72Ford]

Crank position sensor with a distributor to control spark, what a crock of shit.

Its actually not that bad of an idea. There are some high end ignition systems out there that use a crank triggered distributor. Think of the MSD 'flying magnet' type distributors, etc. Accel, and most of the other companies offer variations on the same idea.

In the aftermarket, these systems provide more accurate timing, and they wrok very well.

Maybe the Ford systems couldn't say the same, but the idea itself is actually a good one.

[Merc302]

How would i go about advanced my dist timing on a stock CFI system?

[johnunit]

bumping this back up with a few related questions, as I'm realizing how in over my head I may be here.


Most of my confusion is coming from how to retain EGR and Smog pump functions (no this is not optional for me) while removing the variable venturi system. I guess what I need is some idea or schematics about how they're controlled in traditional DurasparkII setups compared to the current variable venturi system.

For those who haven't been keeping track, I'm trying to retain the stock emissions setup and a mostly stock appearance while switching to a Holley 4-barrel and duraspark II setup, and currently have an untouched variable venturi top end. I believe I have all the EGR stuff in the engine itself figured out, but I'm not clear on what issues I'll run into making EGR operate in a reasonable way while removing the MCU and VV carb from the equation. The same goes for the air/smog pump.

Here is a a couples pictures of some of what I'm dealing with around the smog pump stuff. I'm a bit worried by how washed out many of the colours are on the wires.






I'm also not sure what to do with these coolant temp sensors. I assume one is for the MCU and one is for the Replace Engine Light, so it's just a matter of yanking one and keeping the other?





As for the deletion/jumping of a wire to the distributor that Thain refers to, I think I've figured out that it's the purple striped wire as seen here, of the 4 wires in the same bundle. I don't know though, and sort of forgot why it made sense to me when I was looking at the wiring.





I also managed to get some wiring to crumble just by touching it. only 2 wires seem bad. One of them broke right where you see in the pic, another lost all it's insulation, the rest seem solid. Is that some sort of special connector right where it broke, or can I just run new wires there?





Also, probably a n00b question, but can someone explain the meaning of the different colourings on the emissions schematic here?

[P72Ford]

I didn't mess with most of that stuff, when I converted mine.

I tossed the coolant sensors, because I broke the tall tan one when I swung the torque wrench around, tightening my intake bolts.

The EGR valve on my '88 and my '90 operated purely from engine vacuum. There is absolutely no wiring there. As long as you hook it up to the correct vacuum source (you do not want it open at idle, as it will stall), you will be fine. I'd say to pick up a vacuum signal above the throttle blades on the Holley.

I left all of the original wiring in place when I did my red car (obviously not connected to the VV). I just hid the connectors. The smog pump worked fine, and I was easily able to pass emissions.

Obviously for a truly clean install, you may want to cut back and remove those harnesses, but that was just a driver for me, and I wanted to be able to switch back, if the need arose (I was young and naive, back then). I thought an intake swap was a big deal.

[johnunit]

so you were able to essentially unplug everything from the intake, carb, etc. and replug everything that still had a place to go, and most things functioned reasonably? Would trying to get it as close to a plug-and-play install as possible and then start eliminating the leftover junk that I haven't found a place for be a decent route to start with?


I have a couple "ported" vacuum sources on teh carb I bought from 1980c10, so I guess I'm ok for EGR.


Very good news that the EGR and smog pump are totally separate.

[gadget73]

i dont think anything really plugs into the carb, other than maybe the bowl vent solenoid but I want to say thats actually mounted external to the vv unit. Oh, there is the idle stepper thing but thats vacuum controlled. The choke I'll assume you'll be using anyway.

The jumper wire I mentioned goes to I believe yellow connector off the dspark box. Its got 2 wires in it, but I can't remember what colors they are. Just jump the wires together at the dspark unit. If you read that emissions label, it should say something about doing that to set the timing. Thats actually what gave me the idea to leave it that way permanantly. The distributor will still advance the timing mechanically, but the computer won't be able to retard it electronically with that third connector jumped out.

[johnunit]

Thanks, I'll study the text side of the sticker a bit more and see what I can figure out.

Does black and yellow wires sound right for the connector off the box?

[gadget73]

that could be it. its whatever doesn't go to the distributor or the coil.

[johnunit]

that'd be it. Thanks.

[Mercracer]

Do yourself a favor and get a EVTM. In the meantime I will check my pile for '85 engine wiring diagrams.

[johnunit]

Fair point. It's something that's just never quite been the number one priority when I go ebaying. Obviously it now is.


That'd be great if you (or anyone else) managed to dig it up. It should be pretty much identical for at least a couple years before and after.

[johnunit]

wow. big bonehead move on my part. I completely forgot 4door gave me an EVTM.

[johnunit]

A few more things after studying the EVTM and the underhood a bit more:

There is a red fitting that goes into the thermostat housing (the part that comes off to replace the thermostat). It has three vacuum fittings stacked on top of each other.
Top goes to manifold vacuum directly
bottom goes to a vacuum tee and runs all sorts of junk of various description
middle goes to vacuum advance cannister on distributor


Here's the catch: It's just plain not shown on any of the diagrams. I assume it has some sort of thermal-related sensor, either for when the thermostat opens or a certain temperature is reached, but it doesn't make sense that all these vacuum-driven parts would need the same trigger, and it makes zero sense to me that vacuum advance would be related to temperature, at least in such a crude way.

Is this just a weird spot they found to mount a vacuum tree or?....



stupid question: are the large smog pump hoses the same size as heater hoses?



Can I run the cannister purge solenoid be deleted, so that I just have a vacuum line from the charcoal cannister to manifold vacuum? The EVTM just vaguely states that the MCU "uses various sensors to determine when to actuate the solenoid" but I don't know if it would hurt anything to just have a vacuum line sucking from the charcoal cannister all the time, or whether there's a reason to have it only open at high vacuum or startup or some other situation.

The factory setup for the bowl vent solenoid (controlling the line from the fuel bowl to the charcoal cannister) appears to be on with key in run, and then controlled secondarily by the MCU. I assume I can just have it set for on/open in run constantly once I delete the MCU?

I also found the jumper spot that Thain/Gadget was talking about. Dead simple, it's the two-wire connector coming from the duraspark box. Given that simplicity I don't know that I'll even bother changing boxes.

[gadget73]

it probably blocks vacuum advance to the distributor when the engine is cold or some such nonsense. I've also seen setups that switch from ported vacuum to straight manifold vacuum at a certain temperature.

deleting the canp solenoid is probably not a good idea. It would be a fairly large vacuum leak to be open all the time. You can just plug it off though. If you're deleting the MCU, I'd strip all of that BS out of there and make it a basic vac advance system with no smog controls. Otherwise, you're probably better off leaving it all intact like it left the factory. Smog carb stuff is highly retarded, especially when you mix it with a computer. If its not exactly right, it tends to run very horrible.

[johnunit]

hmm. I didn't trace it to a ported vacuum source, but that does make sense. I'll add it to the delete list.