Inside an Ignition Module
#21
When i talk about this things...i usually say that black plastic thing with some metal tabs... and the other guy says oh yeah the ignition module...the only thing i can say here they are a damn good piece of electronic,they lasted on our cars for 27 years,bougth one from ecklers last year it lasted for 3000 miles... put again the old GM one...
#22
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It's not the voltage. I've read, but never seen in person, concern about magnetic coupling issues between the top mounted HEI coil and the pickup coil. Somewhere someone felt/experienced a concern about a drivability issue, and a particular pairing of the ignition coil part number and the pickup coil part number was supposedly more resistant to this coupling issue. As I mentioned, I have no first hand information or engineering data to determine the validity of this issue.
#24
It's not the voltage. I've read, but never seen in person, concern about magnetic coupling issues between the top mounted HEI coil and the pickup coil. Somewhere someone felt/experienced a concern about a drivability issue, and a particular pairing of the ignition coil part number and the pickup coil part number was supposedly more resistant to this coupling issue. As I mentioned, I have no first hand information or engineering data to determine the validity of this issue.
Last edited by oldalaskaman; 02-18-2012 at 06:33 PM.
#25
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after years...and years of making things work, and working around things that you wouldn't think would work together but did, I think you folks are over thinking an issue that doesn't exist. kinda like contemplating belly button lint. BTW chevys been using this distributer since the real early 70's , that a pretty good track record, all it does is work
OBTW, good luck telling your boss that he's just overthinking any issue, particularly if that issue is potentially in a million cars a year.
#27
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The details of the GM HEI module input circuit are similar to the technical description of the Nat Semi 1815 chip shown here: http://www.national.com/ds/LM/LM1815.pdf
The application notes contain basic design info.
The back end of the 7-pin HEI didn't change a lot from the original GM 4-pin unit of the late '60's. See the Motorola part sheet for the MC3334:
http://www1.jaycar.com.au/images_uploaded/MC3334R0.PDF
The relationship of the pick-up coil(VR) phase to the 'zero-crossing' HEI trigger are shown there too. Generally if you connect the wrong phase you throw the spark signal off by quite a bit.
The relationship of the 7-pin VR pickup, DRP, and spark timing are shown on the B&G figure here:
http://www.megamanual.com/ms2/heiest.gif
edit - that URL is coming up wrong - try www. megamanual. com /ms2/ heiest.gif without the spaces
There is a VERY modest amateur ignition design discussion here, along with a comparable circuit used by MSD and SGS:
http://www.corvetteforum.net/c4/doctorj/heicoilinfo.htm
This info is used to interface different ECMs, trigger wheels, and the like with the Gen 1 small block FI hardware. FYI, the 7-pin HEI system has much in common with the NORTHSTAR DIS package (given a different trigger wheel and VR pick-ups) which will plug right in to the P4 ECM circuits. As such, knowing how these things are put together helps folks who enjoy modifying C4s for improved performance.
That never struck me as 'over thinking' a better way to do something.
HTH
The application notes contain basic design info.
The back end of the 7-pin HEI didn't change a lot from the original GM 4-pin unit of the late '60's. See the Motorola part sheet for the MC3334:
http://www1.jaycar.com.au/images_uploaded/MC3334R0.PDF
The relationship of the pick-up coil(VR) phase to the 'zero-crossing' HEI trigger are shown there too. Generally if you connect the wrong phase you throw the spark signal off by quite a bit.
The relationship of the 7-pin VR pickup, DRP, and spark timing are shown on the B&G figure here:
http://www.megamanual.com/ms2/heiest.gif
edit - that URL is coming up wrong - try www. megamanual. com /ms2/ heiest.gif without the spaces
There is a VERY modest amateur ignition design discussion here, along with a comparable circuit used by MSD and SGS:
http://www.corvetteforum.net/c4/doctorj/heicoilinfo.htm
This info is used to interface different ECMs, trigger wheels, and the like with the Gen 1 small block FI hardware. FYI, the 7-pin HEI system has much in common with the NORTHSTAR DIS package (given a different trigger wheel and VR pick-ups) which will plug right in to the P4 ECM circuits. As such, knowing how these things are put together helps folks who enjoy modifying C4s for improved performance.
That never struck me as 'over thinking' a better way to do something.
HTH
Last edited by DOCTOR J; 02-18-2012 at 09:21 PM.
#30
you're going to hear a few opinions about it , but my opinion is either stock or dui, you're looking for reliability, no matter what fancy words they use or how many ways they explain things , they all do the same thing.
#31
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Regarding no boss, it doesn't help, and it doesn't hurt. I don't care either way. I'm going to take a wild guess that you are not designing and manufacturing a million parts a year that go into a million different cars. If you were, there's a good likelihood that you would have a boss somewhere.
#32
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I try to put out accurate information. Please add your knowledge.
#34
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http://forums.corvetteforum.com/c3-t...s-like-me.html I wasn't posting about your I.Q. I made a statement that personal slurs showed low I.Q. and you were loosing esteem in others eyes by doing it. You obviously have a good knowledge of the C3 ignition system, and I've linked it here because some of the basic tech carries over, respectfully, bob BTW. I am the proud owner of three handguns and two chain saws. See, I even read posters info.
Just trivial history, but in 1983 I was assigned to design a replacement IC for the seven terminal module pictured in the original post, and I did. It worked, and met the specs, but I couldn't achieve a great enough cost reduction in my design (compared to the production IC) to pay for all the required validation testing and documentation updates needed to satisfy the customers at the assembly plants whenever new/updated/redesigned components are put into the production stream, so the project was cancelled. I was disappointed, of course, but cost factors are a way of life in any business, and particularly when the cost reduction is small compared to possible warranty cost risk when introducing new parts in high volume production.
#35
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Take the bickering to PM's gentlemen. If you don't have anything to add in relation to the OP's post, STAY OUT OF IT.
#37
Racer
A bit off topic but questions i have.
wiring diagram says bat voltage to pin "p", i Show 12.63.
sould pin "+" have the same voltage while ignition is in run? I show 1.43. i belive module to be bad. Oriliey's computer says it is good.
my spark plug and ohm meter both confirm no spark condition. fyi all other test are ok.
wiring diagram says bat voltage to pin "p", i Show 12.63.
sould pin "+" have the same voltage while ignition is in run? I show 1.43. i belive module to be bad. Oriliey's computer says it is good.
my spark plug and ohm meter both confirm no spark condition. fyi all other test are ok.
#38
Race Director
Thread Starter
The pink wire going to the distributor comes from the ignition switch. That pin is connected to the three pin connector behind the ignition and tach connectors and also to the ignition coil.
The three pin connector has a cable that goes into the front of the distributor. The ignition voltage is the red wire in that cable and it connects to the "+" pin of the ignition module.
You need to have all the connectors plugged into the distributor cap to see the ~12 volts on the "+" pin.
The three pin connector has a cable that goes into the front of the distributor. The ignition voltage is the red wire in that cable and it connects to the "+" pin of the ignition module.
You need to have all the connectors plugged into the distributor cap to see the ~12 volts on the "+" pin.
#39
Great, you guys are giving out the secrets to the IRON MAN suit!
I took one of these apart back in the late 80s and I still have NOOOOO idea what the heck I'm looking at.. thanx for helping me understand the "how" it works.
I took one of these apart back in the late 80s and I still have NOOOOO idea what the heck I'm looking at.. thanx for helping me understand the "how" it works.
Last edited by TTOP350; 03-20-2012 at 09:27 AM.
#40
Racer
The pink wire going to the distributor comes from the ignition switch. That pin is connected to the three pin connector behind the ignition and tach connectors and also to the ignition coil.
The three pin connector has a cable that goes into the front of the distributor. The ignition voltage is the red wire in that cable and it connects to the "+" pin of the ignition module.
You need to have all the connectors plugged into the distributor cap to see the ~12 volts on the "+" pin.
The three pin connector has a cable that goes into the front of the distributor. The ignition voltage is the red wire in that cable and it connects to the "+" pin of the ignition module.
You need to have all the connectors plugged into the distributor cap to see the ~12 volts on the "+" pin.
the "+" pin just does not show 12.63. hooked a jumper from jumper box to top red connector and coil and fire. damn this thing...new pick up coil, coil, rotor, cap, rotor spring.