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Old 12-20-2008, 04:39 PM   #1
phred3512 OP
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Points to Electronic Ignition Cheap & Easy

Any engine with a 12volt point ignition can be converted to electronic ignition using a Ford TFI module. It is both cheap and easy. More than likely most of those here already know how to do this, but perhaps this can help someone.
Point ignition is a simple example of a digital system. Simply put when the points open the voltage is interrupted on the primary side of the coil and induces a voltage in the secondary. This means that the expanding and collapsing field of the coil is switched off and on by the points opening and closing. If a capacitor is not wired in parallel to the points they would burn out quickly, hence the condenser(cap).
In a regular point ignition the points are a switching device. The idea here is to change the points from a switching device to a triggering device and make the module do the switching. Switching a coil on and off is where the heat is generated and that is what causes the points to burn out.
Of all the digital ignition modules used in automotive applications the Ford TFI is the only common module that fires on the negative to positive transition of the waveform. Since points fire at the same time they can be a good triggering device for the TFI ignition module. Just visit the local auto bone yard and get several Ford TFI modules along with the heat sink, and plug-in. I usually cut off as much of the harness as possible with the plug. It is important to get a module and heat sink pair like the one pictured. The earlier model mounted directly to the distributor and though will work it is more difficult to mount and the wiring is a little different.




Looking directly at the module the bottom right would be wire #1. The illustration spells it out clearly (I hope). I usually just take #3&6, tie them together and hook them to the positive side of the coil seeing that is keyed ignition. #1 to ground, and #5 run to the points. Now you have an electronic ignition that will definitely not work!!! If you disconnect the condenser it will work flawlessly. Again you MUST make sure there is no condenser hooked to the points. The points need only to close and open, the gap is irrelevant
If you just set up a battery on a bench and hook up all the wires as shown you can check the spark by toggling the point lead (#5) with a test light hooked to ground. You will get a nice hot spark out of the secondary. I have pictured one of my forklifts that I did the other day. It really is quite simple and works well on older motorcycles. Single and twins will work fine on one module, but fours need two. Rule of thumb is one set of points one module, two points two modules.


Here is my forklift transmogrification.

Before:





A fine example of modern 20st century technology.



Before going under the knife.







The module.




The module hung.



The whole thing wired up. Notice the precision with which I removed the condenser from the circuit!!!
My forklift ignition is now maintenance free.

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phred3512 screwed with this post 12-20-2008 at 06:07 PM
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Old 12-20-2008, 05:59 PM   #2
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thats cool!

although I generally use the GM HEI module ( $15) and ford TFI coil ( $30)

when I do similar conversions.
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Old 12-20-2008, 08:00 PM   #3
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Hey cool, thanks for posting it.

I've put a couple chrysler modules inline back in the day, the old firewall mounted ones but as you mentioned they triggered on close, so you'd have to turn the distributor so the points would time on closing, on the backside of the cam.

While I agree that gap is not critical for spark, it is important for the dwell angle and so you should at least try to approximate the point gap.
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Old 12-21-2008, 04:50 AM   #4
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Quote:
Originally Posted by mouthfulloflake
thats cool!

although I generally use the GM HEI module ( $15) and ford TFI coil ( $30)

when I do similar conversions.

In my experience the HEI being analog works quite well with any analog triggering device like a pulse generator. The four prong old style ones I used for everything from a Jaguar 12's to a Mazda rotary engine. Being that they have a pulse type trigger in the distributor they will cause the module to switch whenever it senses the triggering signal change from positive to negative. I have never tried them in a digital setting, but it is interesting that you mention them working. I have never changed the coil unless the old one was bad.
Thanks,
Danny
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Old 12-21-2008, 04:52 AM   #5
phred3512 OP
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Quote:
Originally Posted by GreaseMonkey
Hey cool, thanks for posting it.

I've put a couple chrysler modules inline back in the day, the old firewall mounted ones but as you mentioned they triggered on close, so you'd have to turn the distributor so the points would time on closing, on the backside of the cam.

While I agree that gap is not critical for spark, it is important for the dwell angle and so you should at least try to approximate the point gap.
I had considered the method you mention with other modules, but not all distributors have enough of an arc to allow for timing also. While dwell is controlled by gap in a contact breaker system in the TFI module it is controlled by the current limiting circuit.
I appreciate your method, it answers an old question I have had in the back of my mind for years.
Thanks,
Danny
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Old 12-25-2008, 11:07 PM   #6
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Old 12-29-2008, 10:52 AM   #7
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Phred.

years ago, I rigged an ould outboard motor up with an HEI module ( 4 pin)

outboard ignition, had a distributor, with a hall effect trigger.

researched the IC used in the GM module, motorolla dont remember the part number.but it required less than 0.3 or 0.03 voltage differential to trigger.

not much at all.

I routed 12 volts thru the hallefect trigger, simply as a signal voltage, and picked it up on the switched side with the HEI module.

there were a couple of 10watt resistors in there to pull it to ground also.

it worked well, that HEI module is a very useable, well designed unit that is available CHEAP.
it needs a heatsink though, to really live long, and its a bit current hungry, 4-6 amps if I recall to sting the coil.

the ford TFI coil seemed to have the best wind ratio and internal resistance to run cool and give a big spark with the HEI.

again, YEARS ago, my memory isnt so good.



Quote:
Originally Posted by phred3512
In my experience the HEI being analog works quite well with any analog triggering device like a pulse generator. The four prong old style ones I used for everything from a Jaguar 12's to a Mazda rotary engine. Being that they have a pulse type trigger in the distributor they will cause the module to switch whenever it senses the triggering signal change from positive to negative. I have never tried them in a digital setting, but it is interesting that you mention them working. I have never changed the coil unless the old one was bad.
Thanks,
Danny
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Old 01-01-2009, 07:44 AM   #8
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This is good information. It makes sense to me that the HEI would work well the way you describe seeing it would also fire on the negative to positive transition. It would also work on motors that do not have a distributor like the TFI does. A real plus.
I have used them in the past on any analog distributor. I once used one on a Mazda rotary engine that had two modules mounted on the dist. Since the modules themselves cost over $400 each we looked for an alternative. We also found that a little dia-electric grease on the back and the firewall as a heat sink worked sufficiently. The four prong modules used in the early Chevy's worked best as I remember. My method was to test the output on the distributor's pickup with a VOM on AC voltage. Just hook to the two wires coming out of the pickup to both leads of the VOM and spin it over. If you get voltage it works and will trigger the module. If no voltage.....pick-up bad.
One time years ago a shop called us with a Jaguar 12cyl that would not run. I tested the pick-up and it was good. I informed the manager that the module needed to be replaced and I could do it cheap with a Chevy HEI and save the customer a bunch (the Jaguar module was just under $500). The customer wanted the OEM module. I was ready to order one from the dealer when just out of curiosity I decided to open up the original module. It was an aluminum box about 3x6 inches with a power transistor mounted on the side and you guessed it, inside was an HEI module. Yup fixed it for about $20!
Generally I try not to replace coils on older applications because sometimes the hotter spark will cause older distributor caps to arc and they can be a bear to find.




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phred3512 screwed with this post 12-26-2009 at 01:57 PM
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Old 01-01-2009, 08:40 AM   #9
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yep, those TFI coils can have massive spark energy.

especially when you remove the ballast resistor and saturate them with the FULL system voltage.

thats a funny story about the JAG ign module.

why reinvent the wheel?

haha
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Old 09-09-2010, 12:26 AM   #10
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Hi,
I know this is an old thread but I was hoping someone could tell me - what model Ford's are these new type modules common in? I'm in Australia and it seems that most fords I've looked at run the ones that are on the distributor.
Any help is much appreciated.
Cheers!
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Old 09-09-2010, 07:46 AM   #11
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Gday man.
Scrounge the wreckers for EF, EL, AU Falcons. I know the V8 models have them. The Chevy HEI module they're talking about is the same as the ones found in our Holden V8's, and also in the earlier XF Falcons the module can be wired the same as the HEI.
I rekn you should be able to find one of those local.......
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Old 09-09-2010, 05:57 PM   #12
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If you have one of the distributor mounted modules laying around you can wire that up, here are the differences-

The distributor mounted module has 3 extra terminals on the top that stick up. The one closest to the middle of the module - in other words, the one that is towards the other end with all the terminals- is used instead of the "top" terminal in the picture at the top of this thread. It is the one labeled #6.

So just run that wire from #6 to the other top terminal and figure out a decent heat sink and you'll be good to go.

BTW the module illustrated at the top is used on a lot of 94-95 vehicles so look for those years at the scrap yards.
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Old 09-09-2010, 07:31 PM   #13
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Thanks for this information, I am going to try this on my 1976 BMW R90.
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Old 05-18-2011, 04:06 PM   #14
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great idea always wondered if it could work...

Cool Idea and a great post. I am wondering(since my dyna III seems to have taken a crap) if I can use the mechanical advance from the dyna kit to rig the TFI ignition on my r90? Or is it using something more advanced than a simple trigger like the points do?
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Old 05-09-2013, 04:35 AM   #15
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Tp100 module for points conversion

Hi there
Does anyone know if this conversion can be done using a tp100 module ?These are used in the Volkswagen Golfs here in South Africa and are cheap and readily available . If they can be used does anyone have a wiring diagram for the conversion. Any advice will be gretlty appreciated as i do not have much electrical experience
THANKS
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