I have basic knowledge I guess you can say. I have built a few simple circuits but nothing very complicated. One of the things I've been thinking about is controlling the A/C functions on my RR with maybe an Arduino. My care has factory air but the heater core is bad, the condenser doesn't look any better and for the cost of replacing them I can go to after market but I want to use my existing A?C control switch cluster on the dash. Since systems like Vintage Air now have electrics controlling the dampers like modern cars do I think this can be done but that would be another discussion. As to the ignition I have on the car it is a MOPAR Electronic. with a mid '70s dist that still has mechanical and vacuum advance. I have plans to replace the MOPAR module with a GM module and put it under the fender well so it just looks like points under the hood and also eliminate the ballast resistor. You said you can trigger off a set of points, is it possible to trigger off the tach signal post on the 7 prong HEI module? Best I understand this is a square wave and the timing function is mostly nothing more than that giving a variable band width to this signal and sending it back to the module while including dwell time in the signal. Since my car has a magnetic pickup that is what I would have to try to do. My motorcycle is the same way. I am a IBM I programmer, I've not done a microcontroller but it should not present a problem, just some studying. The part I would have the hardest time with is the circuits themselves. When/where to use capacitors and resistors and what values to use, etc..... Or even which micro would work better for which functions. I do know for this it would need to have a pretty decent clock speed.

We're kind of in the same boat. I've been tinkering with computers here and there since the Commodore days, but over the last ten years have gained a lot of knowledge on the inner workings and such I never understood before (I wish the internet was around when I was first introduced to computers). As far as electronics go it's just a hobby.

As far as the tach signal off the HEI is concerned from what I could find so far I believe it should be a square wave... the schematics I've found seem to show it should work that way.

I've spent some time rethinking things and going over what I've done so far. I've come up with several possible places where noise could be introduced that I knew in the back of my mind should have been isolated with optocouplers at first.

I will keep you updated when I get to giving it another try. I've been concentrating on getting some stuff going with the Raspberry PI lately (wishing I would have paid more attention to them a while back) and haven't felt the urge to get back at this project.

 

We're kind of in the same boat. I've been tinkering with computers here and there since the Commodore days, but over the last ten years have gained a lot of knowledge on the inner workings and such I never understood before (I wish the internet was around when I was first introduced to computers). As far as electronics go it's just a hobby.

As far as the tach signal off the HEI is concerned from what I could find so far I believe it should be a square wave... the schematics I've found seem to show it should work that way.

I've spent some time rethinking things and going over what I've done so far. I've come up with several possible places where noise could be introduced that I knew in the back of my mind should have been isolated with optocouplers at first.

I will keep you updated when I get to giving it another try. I've been concentrating on getting some stuff going with the Raspberry PI lately (wishing I would have paid more attention to them a while back) and haven't felt the urge to get back at this project.

LOL, see I don't know what an optocoupler is, that is why I didn't think I can do this myself. I've been looking at some Aurdino projects for ignition but I don't see anything using the 7 pin HEI module and I think that would be the simplest way to go, you can pull the square wave and just modify it and send it back.

I've looked at Raspberry Pi, mostly for a TV video box. Right now I have a PC on each TV so I can stream stuff, mostly motorcycle racing. I also use HULU through them. I have Kodi installed and mostly use it when watching something old that is in 4:3 because it has a non-linear stretch that makes a 4:3 into a 16:9 without making everything look fat. I works well. I have old shows like Rockford files, The Marshal, Then Came Bronson, etc... that I watch when I was growing up.

Just keep me posted and I'll let you know if I come across anything that I think might can help.

 

Just keep me posted and I'll let you know if I come across anything that I think might can help.

I did finally put together a little sketch of the basics of what I have put together so far ignition wise. It's a bit more involved due to other things I have going on with the project, but this should get the basics covered.

The parts:
Distributor - Ford Duraspark. Since you have your Mopar connected to a HEI module already you've figured out they all work the same more or less.
MAX9924 - I picked up the http://www.jbperf.com/dual_VR/v2_1.html#Buy board to try. I also tried a home made test board with the 9924 itself. The 9924 is super small, but can be done on a home made board with plenty of patience or some better tools (a rework station would have been nice). The prefab unit and the home made unit both worked the same when wired up to a ABS sensor on a trailer at work, and also with a speedometer sensor I have laying around. I whipped up a small project that averaged times between pulses and calculated the difference from the average for a test. Stay away from the 9925 and 9927 for sure as they're overly complicated for this application in my opinion. The 9926 (which is at the heart of the above link) may also work on a home made board, but it's twice the pins and three times the patience I'm sure.
Q1 and Q2 - n channel mosfet (BS170)
C1 - 2200 uF @ 35 v -- it may not be the best choice as I have lots to learn, but it was laying around.
D1 - 150 v / 10 a schottky diode (SB10150TA)
D2 - 24 v / 3 a tvs diode (PESD24VS1UA)
C2 - 10 uF @ 35 v -- another one I just had laying around
OKI78SR - Murata Power DC - DC switching power converter 5 v out up to 1.5 a.

A little about how it's supposed to work.
The top section:
I made an inverted and non-inverted output to test to see if I could find any difference (by ear and feel) when switching the distributor pick up wires to see if the chip likes a positive to negative transistion or negative to positive transition better. I thought I saw in the datasheet you should use the positive to negative transition, but I can't seem to find it again. It seems to work the same either way. I have it hooked up through the mosfet now just for a little added safety in the event the wire to the HEI shorts somehow. (the 9924's themselves do have short circuit protection, but aren't the cheapest way to go... Thery are worth the extra cost from what I gather so far).
The connection to the 'P' terminal of the HEI is only used for starting and as a 'limp mode' feature. Once the rpm reaches 600 the microcontroller will take over. The 'N' terminal of the HEI is connected to ground. I also added a couple jumpers (like the old settings jumpers in a pc) to bypass the 9924 altogether which connects the 'P' and 'N' to the distributor as it was originally designed to be.

The middle section:
My application is actually a bit more involved due to the need to have 5 v constant as well as switched 5v. I've done some digging and from what I can tell this is the bare minimum you would need. It works well with the digital side of the project, but it's a noise suspect in the analog side. I picked up 10 mH 3A common mode choke for the power into the converter, and a 1 mH 3A common mode choke for the output side of the converter based on some generalizations from other research on the web. Whether they will help or not is yet to be seen...

The bottom section:
I'm using a PIC24F32KA304 for a microcontroller. The signal from the MAX9924 is connected to an interrupt pin on the PIC which reads and resets a counter to calculate time between triggers. Rough calculations show I should be able to handle around 7000 rpm with the programming I have so far before the intterupts start colliding with the standard 8 pulses / revolution of a V8. I also have a standard GM MAP sensor connected to a ADC pin to measure mainifold vacuum to calculate vacuum advance with. The water temp sensor isn't necessary, but I thought maybe it may help to advance the timing a little more on those frigid nights after work until it starts to warm up (something else to test out). It also runs a relay to turn on the electric fan behind the radiator to handle cooling.

The PIC has a table in program memory that is used to caculate everything out. Each row is for a different rpm range. The first column of the row has the dwell time stored in it for that rpm range. The following columns contain offsets to subtract from the counter value read at the beginning of the interrupt which is used to set a timer that pulls down the signal to 'E' on the HEI to turn off the coil. The dwell time is then subtracted from the original timer and used to set another timer that releases the signal to 'E' to let it go high and start charging the coil. Since the PIC itself doesn't have any current limiting on it's outputs I added the pull ups and set things up as open drains for all signals that originate at the board to off board devices to hopefully save things in the event of a wire rubbing through or shorting out somehow else.

I'm sticking with the 9924 for the trigger until I get everything working correctly and then try to see if the tach signal from the HEI module will work or not.

If you're feeling adventurous I think this will get you started on the basics. I have a LED now connected instead of the HEI which is how I found the noise issue. It should stay off and does for the most part as long as the engine isn't running, the turn signals are off, the blower motor is off, and basically no change is made on the electrical load. It's possible it will work without too much effort. I may have just overcomplicated things and created my own problems.