Another Distributor and Ignition question

[yz400e]

HI,

I have a 1976 J10 c 360 V8

I was on here earlier this year with questions relating to converting the ignition to the more modern Duraspark / Large Cap / TFI coil set up. Before I could get the vehicle to run I returned to work and haven't had a chance to look at it since. I do appreciate the help I received at that time though.

I will soon be home soon so I started re-researching ignition options.

During my searches I noticed that MSD makes a distributor with the ignition module included in the distributor but it still uses an external coil. They call it the "Ready To Run". https://www.msdperformance.com/products ... parts/8523

In all the threads I have read on here regarding upgrading the ignition I have not seen this particular option mentioned. Is that because it is junk ? By "junk" I was thinking about the module being inorporated inside the distributor. is the external 6A plus a better module than what is incorporated into the "All In One " ? Has anyone used it or know of anyone that has tried it ?

I'd like to use as little of the factory wiring as possible due to it's sorry state and this looked interesting.

Edited to be more specific
thanks

[REDONE]

No, it's not junk. It's just really expensive for what it is. You get the same benefits at a fraction of the cost by using any of the ignitions that are popular here. Hope this answers your question!

[tgreese]

If you want a magnetic trigger distributor, the obvious choice is a '78-up Motorcraft Duraspark which is factory equipment for these Jeeps. It's a fine distributor, and the VR design (variable reluctance) is an industry standard, even today (unlike your orphan Prestolite BID system). I expect the MSD distributor has a VR trigger. The drawbacks I can identify with the Duraspark is 1) there are no new ones available 2) the factory wiring connector tends to crumble and corrode after 20 years of service and 3) there is no replacement vacuum advance diaphragm available, other than buying a remanufactured distributor (the rebuilders are refurbishing the diaphragms). With a VR trigger, you have your choice of several modules, including Duraspark, HEI and MSD.

An alternative would be a Delco points distributor for a '74 or earlier Jeep. The points distributor can trigger a MSD module. There is a big cap option using HEI-style wires using the MSD cap-adapt. The MSD module takes over the coil switching, so the points will last a very long time. You can also switch back to the Kettering trigger (points) to switch the coil, in the unlikely event the MSD module fails. It's also possible to go pointless with the Delco distributor - either by fitting a Pertronix module and connecting to the points trigger of the MSD module, or by converting the distributor to a VR trigger (article online), and using one of the several modules that accept a VR trigger.

Then there are the myriad GM HEI knockoffs... which the MSD all-in-one seems targeted to compete with.

[babywag]

http://www.ebay.com/itm/Amc-Jeep-290-30 ... ak&vxp=mtr

Or, reman duraspark distributor.
Like stated for module pick your poison many options. I wouldn't use an aftermarket duraspark module though.
MSD distributors are nice, but stupid overpriced IMHO. I mean seriously $400, for a little more can buy a used ls engine lol.

[yz400e]

Thanks,

It makes sense that it would be intended to compete against the HEI replacement style. I agree that $419 is a lot of money. I am almost tempted to try the Summit brand HEI style for ~$160. My current thought is to reduce the number of possible causes for why there is no spark.

As someone mentioned, the truck originally had the Prestolite system. However, one of the myriad previous owners had converted it to points. I was trying to do the same upgrade that Tgreese suggests but it didn't work and I ran out of time. (see picture). I have the chinese NAPA module, a rebuilt distributor Motocraft distributor (1983 model year) and I recreated the wiring that was completely missing. (only partially complete in the photo).

harness_1.jpg

I think I was trying to follow this diagram and adapt it to what is in the 1976. I also have another diagram from the manual for the 83 that I was referring to.

dura01.gif

When I first acquired the vehicle and tried to start it, the spark was intermittent. The engine would fire but then spark would just drop out. So we pulled a spark plug and cranked the engine over and watched the spark it would be there for 10 or 15 seconds and then drop out. We could then try cranking the engine 4 or 5 times with no spark and then it would reappear for a few seconds and go away. Could this be due to the ignition switch ? isn't there another mechanical type switch in the steering column as well ?

When I last worked on it, I had NO spark at all and as I was by myself and didn't have a remote start button I don't know if I"m getting voltage at the points I should be due to an error in the harness, I fried the module already, or if it is something else.

Is there is something i need to check in the steering column ? could this be the actual problem ?

[tgreese]

Could be the ignition switch. Have you replaced the coil? A coil can be intermittent. Points ignition is pretty simple - my advice would have been to get it running reliably with the points distributor. You have made things considerably harder by introducing new components and wiring to a system that already has a problem.



I suspect the junkyard genius diagram has an error. I will explain below.

The circuit for the Duraspark modulehas a lot in common with the points ignition circuit. Look at the diagram and let me point out what's connected where. You need to use the diagram and also understand why its connected that way.

The running circuit - 12V is connected to the coil through the ignition switch, via the resistance wire. The resistance wire limits current through the coil, since the coil and module cannot stand too much current for a long time. The green wire turns the coil on and off by alternating between grounded and floating (connected to nothing - "floating" in mid-air). Inside the module is a big transistor that the module electronics turns on and off, just like the points open and close. The module is simply an electronic replacement for the points - it does nothing to change the intensity or duration of the spark.

When starting, the resistance wire to the coil is bypassed, so that the coil gets full current. This makes a stronger spark when starting. Power comes from the "I" terminal (ignition) of the starter solenoid, and goes to the coil. This should not connect to the module. Module power should be a separate wire that is powered during starting and running.

Let me point out what each wire to the module does.

The red wire is the module power. It should be at full battery voltage during starting and running. Connect that to the red wire that originally went to your Prestolite module, not to the red coil wire.

The white wire is a logic signal that retards the spark during starting. It is correctly connected to the blue "start" wire from the ignition switch. By connecting to the "S" terminal of the starter solenoid, the blue wire turns the starter solenoid on to run the starter motor. The starter solenoid also has the "I" terminal (ignition) that can be used to power the ignition during starting.

Some starter solenoids do not have the "I" terminal. If that's what you have, I suggest you get a new replacement that will come with the I terminal.

The green wire controls the coil. It is alternately grounded and floating, depending on the magnetic VR signal from the distributor.

The black wire is a ground. As shown in the diagram, an extra ground connection to this wire (in addition to the connection to ground at the distributor) can only help.

The orange and purple wires are the magnetic VR trigger signal from the distributor. They are polar, so violet must connect to violet, and orange to orange. The original wiring is made so you can't get the polarity backwards, but if you are wiring the module yourself, be sure to get the polarity right.

If you are going to copy a Jeep diagram, I suggest you use this one - http://oljeep.com/gw/elec/78/78_FSJ_Wir ... mPage7.jpg - this is the 1978 diagram, and should be very very close to the factory wiring for your '77, except using the Motorcraft ignition instead of the Prestolite. It will also have a resistance wire for the Motorcraft module, which the Prestolite ignition does not use. Use a ballast resistor in place of the resistance wire. Here's a suitable part - http://www.rockauto.com/en/moreinfo.php ... 65&jsn=427

[Mtnmax]

I was skeptical about the cheaper Summt brand distributors, but I had good luck with the Summit HEI distributor in my 401. I ran it for 5 years without any trouble until I sold it (the CJ5) last month.

[yz400e]

Thanks. I have a lot to study.
Yes, keeping the points in probably would have been simpler but I figured all those parts were so worn out that it could be an issue.
The prestolite module was absent when I got the vehicle and I saw no place where it would have plugged in. If there were cut off wires I didn't see them.
There is a new TFI coil plus I have one from a Ford 460 that I can try if necessary.
A new ballast resistor was inserted, but based on what you are saying I think I have it in the incorrect location in the circuit.
The ground wire was spliced at the module and a ground to the fender added.
There is a new starter solenoid too. The solenoid in the vehicle was only 3 posts and it looked like I needed 4: Battery, Starter, (S) and (I) . So I got that right.

Splice L (see photo) has a myriad of wires coming out of it. since they all come from the same red/white wire that came straight from the firewall it shouldn't matter which wire I choose should it ? some of them are used but I seem to recall 2 wires that had nowhere to go so I picked power from one of them and ran it down to the ballast resistor. But what I think did with the power coming out was wrong. I just can't remember right now.

splice L.png

Trgeese says:
When starting, the resistance wire to the coil is bypassed, so that the coil gets full current. This makes a stronger spark when starting. Power comes from the "I" terminal (ignition) of the starter solenoid, and goes to the coil. This should not connect to the module. Module power should be a separate wire that is powered during starting and running.

With that in mind , when I look at the junkyard genius's diagram the power from the I post on the solenoid is going to the module so that definitely . so that is wrong too and I think I wired it that way.

I'm going to submit this or I'll lose all if it. but i had another comment.

[yz400e]

84 TFI EEC wiring switch.jpg

here is a photo of the wiring coming out of the duraspark and a photo of the pigtail I removed from an 84 ford in the junkyard.
It looks to me like the red and white wires are switched. the connector is keyed so do I assume the wiring from the module is correct or incorrect ?

[tgreese]

Getting the points ignition working perfectly would have let you tackle one problem at a time. It kinda worked... Then you could move on to upgrade.

The I post is only on while the starter is running. It's connected to the big post that goes to the starter motor. When the key is at run or off, it's floating. In that diagram, the power to run the module after starting comes from the key through the resistance wire. There will be a voltage drop due to the resistance, and more of a voltage drop because of the extra load from the module. It may be ok and work, but it's not the way the '78 Jeep is wired up. Take a look at the link I posted above, and the next sheet to the diagram. Get your colored pencils and color the relevant parts (no joke - it will help) or write out on another paper the same connections you have on the JG diagram, using the '78 diagram as a guide. Power for the module comes from the splice L which goes through the fire wall and I'm sure back to switched power (look at the next sheet), where the resistance wire originates. This bypasses the resistance wire.

Sorry I can't spend a lot of time on this right now. I will be busy for the next few days - I will come back to the thread when I get a chance.

[yz400e]

No problem. I won't be able to do anything for 2 weeks. I was trying to get a 'head start' on what I may need.

what you have suggested and told me should work. Either way I'll post my results.

thanks again.

[yz400e]

Nothing ever seems to go as planned, mid september turned into mid october before I was able to work on the jeep and then I only had 1 week.

Tgreese and others were really helpful so I thought I at least owed them an update.

I read through all the suggestions, retraced all the wiring, made some corrections to the wiring in the engine compartment and I now had spark but it was intermittent. So then I re-read this thread and saw the comment about replacing the ignition switch and decided to try that next. I ordered the switch and also ordered a new lock cylinder because the one in the vehicle was completely worn out, and while I had it apart I had to replace the plastic turn signal indicator part as it was cracked and broken in several places.

Lo and behold after replacing the switch on the column it fired but would only run on gas poured into the carb.

I had replaced the tank, pickup tube / sending unit, rubber fuel lines, fuel filter and fuel pump back in 2016 but no fuel was getting to the engine. I tried priming the fuel pump as as well preloading gas into the lines but it still didn't work. however, it would suck gas out of a gas can so I went back over all the connections and found where some of the fittings were loose. Tightened those down and I now had fuel to the engine.

now it fires right up but runs like sh!t because something is wrong internally.

Even though I went about this completely ass backwards and spent way more money than I should have (just to get it to the point where I could determine how the engine ran) I'm not too upset. I can still use all the parts on either an engine swap if I rebuild this one.

I have been back at work since early Nov and there is already a foot of snow in the yard so it may be next spring before I work on it again.LOL

why rush it right ?

[yz400e]

the steering wheel is nearly broken into 3 parts. It is so bad I didn't even put it back on as I think it would probably break on me.

I guess Ebay or a wrecking yard is my friend if I want JEEP. are there other marque's that will fit ? will any 70's GM fit ?

thanks,

[Stuka]

the steering wheel is nearly broken into 3 parts. It is so bad I didn't even put it back on as I think it would probably break on me.

I guess Ebay or a wrecking yard is my friend if I want JEEP. are there other marque's that will fit ? will any 70's GM fit ?

thanks,

And Squarebody GM wheel should fit as I recall. Also lots of after market ones.

[tgreese]

I got a PM about this thread asking about converting from Prestolite to Duraspark, specifically about the blue wire. I'm copying the reply here.

You can use the red power wire for either module.

The red wire sends power to the module, same for Prestolite or Duraspark. Ignition on, you have power to the module. Suggest you refer to the 1978 wiring diagram on the Tom Collins site and follow that. This is circuit 13A, and is different from the power feed to the coil 13B.

Circuit 13B on a Duraspark goes to a resistance wire that feeds the ignition coil while running. You need this resistance to keep from melting the module. The Prestolite module does not need this resistance wire, and it's not present on a Prestolite Jeep.

The light blue wire to the module is not present on a Prestolite Jeep. The Duraspark module will retard the spark while starting for easier starting. The blue wire signals the module to retard the spark, and thus connects to the start terminal S on the solenoid. The start terminal is also connected to the ignition switch, same as a Prestolite.

The Duraspark uses a different starter solenoid too. The factory starter solenoid for Prestolite has one small terminal on top, S for starting. The Duraspark solenoid also has an I terminal that bypasses the resistor for hotter starting. All replacement solenoids have both an I and S terminal, and you don't use the I terminal for Prestolite.

[letank]

Need parts... check your local jeep ranch, I have no financial interests in this post

http://montanaoverland.com/