Rebuild your Bosch ICM...

lookforjoe said:
Can you take a pic of the dist. guts? The power stage you linked is typically used with a Hall switch (not a coil-winding), Vs. the old-style trigger wheel/coil winding setup of the X1/9 (putting aside discussions of whether the old style setup on the X1/9 is considered "Hall effect" - we've been down that road before)- I would not expect them to be interchangable. Does the Yugo dist have the same mechanical advance curve in it's body, or was the curve set in the ECU? Not familar with the Yugo variant.
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Here are what I have to work with. The top most part is the 4 point star rotor/gear thingy. Its clearly missing the dizzy rotor which is cheap and easy after I get it disassembled, sanded and lubed. It needed some work to get to turn.
IMG-9990.JPG IMG-9991.JPG IMG-9992.JPG IMG-0003.JPG
 
Looks like you could just use your Fiat dist with the Yugo wiring - the coil winding is the same as the X1/9 style. Why do you want to use this dist?
 
Far as I remember, the Hall type does a relatively low voltage transient pulse to ground, (half-wave) whereas the coil type does a relatively low voltage transient pulse above and below ground. (full wave)
The Bosch unit should work for either one if wired properly.
 
AK, sorry I don't recall the reason for using this Yugo ignition...do you have a points system that you want to replace with a electronic one? Or do you have a electronic one that needs repair? Or are you completely missing the ignition system? Knowing the intent with the Yugo parts may give some thoughts for how to best proceed.
 
It is easier to get an accurate pulse off a Hall Effect type without much signal processing. The coil type output is highly engine speed dependent, and I recall reading an article about the circuit tricks used to get an accurate and stable output. I think you would want to confirm what type you have before selecting the circuitry behind it.
 
dllubin said:
It is easier to get an accurate pulse off a Hall Effect type without much signal processing. The coil type output is highly engine speed dependent...
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Agreed, but most of the folks here have been using the coil type pulse trigger for decades without any major issues. I suppose (for racing) you might want to clean that up a bit, but for road use, I think the coil type has proven itself to be quite reliable. Certainly economical. My initial intent of this post was to show folks that they could rebuild their Bosch ICM with improved results for very low cost. Several have done it with positive results. I haven't seen the hall-effect points replacements used as much as I've seen the coil type, but I'm pretty certain it would work with the modified module. I've not heard any feedback regarding instability, but I haven't personally used the Hall-effect replacement in a points unit dizzy, so I can't say much one way or the other in that regard, but at less than 8K RPM, the coil type maintains a clean and stable pulse. The ICM, well, that's another story. The replacement I suggested in the top of this post (in place of the original Bosch) actually works better and draws less than half the current. Several here have done it and seem to like it.
 
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bbrown said:
Agreed, but most of the folks here have been using the coil type pulse trigger for decades without any major issues. I suppose (for racing) you might want to clean that up a bit, but for road use, I think the coil type has proven itself to be quite reliable. Certainly economical. My initial intent of this post was to show folks that they could rebuild their Bosch ICM with improved results for very low cost. Several have done it with positive results. I haven't seen the hall-effect points replacements used as much as I've seen the coil type, but I'm pretty certain it would work with the modified module. I've not heard any feedback regarding instability, but I haven't personally used the Hall-effect replacement in a points unit dizzy, so I can't say much one way or the other in that regard, but at less than 8K RPM, the coil type maintains a clean and stable pulse. The ICM, well, that's another story. The replacement I suggested in the top of this post (in place of the original Bosch) actually works better and draws less than half the current. Several here have done it and seem to like it.
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I think the bad combo could be a coil type pickup with Hall Effect electronics, but like you say, most people are starting with the coil type system which would likely work OK with either type. I thought your write up on the ICM rebuild was great. Actually, that is how I fell into reading about the different input circuitry approaches on these GM type ignition modules. I have a Bosch distributor but no ICM so I was going to build something similar to what you described but with a generic box (and probably a generic connector unless I come across one that fits the distributor). I was somewhat surprised at the variety (and price range) of those GM modules and that prompted me to get a little design info on the subject.
 
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Dr.Jeff said:
AK, sorry I don't recall the reason for using this Yugo ignition...do you have a points system that you want to replace with a electronic one? Or do you have a electronic one that needs repair? Or are you completely missing the ignition system? Knowing the intent with the Yugo parts may give some thoughts for how to best proceed.
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I have a points system now and have been slowly on the lookout for a pointsless system for cheap. I thought this one should work. I did pick up the coil and everything with it I believe.

I need to do some research on the different types, Hall vs Coil type. This one is a hall effect sensor correct? I thought all pointsless systems were, or at least all older dizzy pointsless systems were Hall Effect. What is the coil system?
 
I don't know how much of it is semantics or sales marketing or internet hype or what, but common ignition system terms that get thrown around a lot for these distributors are reluctor, variable reluctor, capacitor, magnetic, impulse, trigger, hall, electronic, pointless (one of my favorites), etc. I realize there are real differences between them but my point is the terminology is frequently misused or confused.

AK, PM me about the stock electronic ignitions when you get a chance.
 
Looks like an interesting project. I haven't done any meaningful soldering before, what "soldering station" best suits this kind of work?
 
Dr.Jeff said:
I don't know how much of it is semantics or sales marketing or internet hype or what, but common ignition system terms that get thrown around a lot for these distributors are reluctor, variable reluctor, capacitor, magnetic, impulse, trigger, hall, electronic, pointless (one of my favorites), etc.
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How about "positional pulse generator". ;)
 
Jimmy II said:
what "soldering station" best suits this kind of work?
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There are only a couple of places that need to be soldered with this mod. And frankly even that is only if you want to make it fit into the stock box for a stock appearance (due to clearance issues). Otherwise the module could be mounted an any heat sink and the connections could all be done with crimp-on connectors (of the appropriate size to fit the prongs on the module). So the type of soldering gun may not be that particular, if needed at all. But others that know more about soldering can offer much better info if you want to buy one.

Let me know if you are considering this mod and I'll send you a write up I did documenting one of mine.
 
I’d like to install the Midwest perf head some day, so the Ignition upgrade with the 8,000 RPM capability has real appeal.

Would welcome more info.

The soldier connection of the six wires to the internal pins looks like it could take finesse.
 
I have not had any issues with the system using points in the 74 - 78 cars at 8,000 rpm. I suspect the Bosch electronic system with or without the mod would do the same. Remember that 8K in a 4 cylinder car has the same ignition demands as a V8 at 4K which is not very difficult to achieve. If you want to go to a much hotter spark, that is another matter although my experiments with the standard ignition versus a CD unit with a much hotter spark did not seem to make any noticeable difference in performance.
 
is it just me? or have the pictures back on Page 1 all disappeared. Can the instructions be reposted? I'm ready to do one myself!
 
The link to the PDF is still there in Bob’s first post.

I will repost it here.

Bob Brown

Rebuild your Bosch ICM for about 10 bucks

The attached PDF is the work of Bob Brown.
 

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You just saved me Bob! Thank you so much! I suspect my ICM is bad (lost spark - and checked everything else). RockAuto had this GM part as a replacement but I had no idea what to do with it. Now with your instructions, I have a replacement coming this week and couldn't be more happy to eliminate the ICM issue from my lack of spark problem for CHEAP!
 
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