We don't mean to torment you, Bill. But if you do the tests, you'll have a keenly interested audience here.
Jordan
On using GM HEI ignition modules
Moderator: ajleone
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DewCatTea-Bob
- Posts: 2897
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- Location: Near SE side of Lake Michigan
Component Testing Set-Up
By: wcorey...
" This was just an incidental side project and only implemented because I had the necessary hardware on hand,
Actually I already made and subsequently misplaced a mandrel
I suppose it could be easy enough to mount a magnet on a shaft and affix a pickup coil to something nearby. "
____ If you still have your pictured set-up about as seen, (or can place the hopefully handy components together like you had in your picture), it seems that it would be fairly easy to do any number of such tests.
__ For Bill, I'd expect that he would be fairly well interested even for his own-self to see if he can find that it's possible to supplement the advance-range of one of the stock AAUs with the advance-effect that Jordan & I expect from the pick-up & magnet set-up as used by Ducati.
Cuz if I'm correct, the space between the magnet & pick-up could be somewhat adjusted to obtain a (more desirable?) variance in auto.advance effect to be used, (if not alone), in combo with either of the two originally-stock AAUs.
__ It's a really very neat pair of projects that Bill has started with finding both a good way to eliminate the contact-points and also increase the auto.advance range-span !!
But it would be a bit of a shame to advance-onward with those two aspects being completed by their own separate methods, without ever having realized for sure whether or not they both could've been accomplished with just one modification method.
I'm sure Bill has begun to realize the possibilities and will probably get to what he wishes to get done, in due-course.
__ I've included below Bill's related picture, to be viewable in it's entirety here.
Hopeful-Cheers,
-Bob
" This was just an incidental side project and only implemented because I had the necessary hardware on hand,
Actually I already made and subsequently misplaced a mandrel
I suppose it could be easy enough to mount a magnet on a shaft and affix a pickup coil to something nearby. "
____ If you still have your pictured set-up about as seen, (or can place the hopefully handy components together like you had in your picture), it seems that it would be fairly easy to do any number of such tests.
__ For Bill, I'd expect that he would be fairly well interested even for his own-self to see if he can find that it's possible to supplement the advance-range of one of the stock AAUs with the advance-effect that Jordan & I expect from the pick-up & magnet set-up as used by Ducati.
Cuz if I'm correct, the space between the magnet & pick-up could be somewhat adjusted to obtain a (more desirable?) variance in auto.advance effect to be used, (if not alone), in combo with either of the two originally-stock AAUs.
__ It's a really very neat pair of projects that Bill has started with finding both a good way to eliminate the contact-points and also increase the auto.advance range-span !!
But it would be a bit of a shame to advance-onward with those two aspects being completed by their own separate methods, without ever having realized for sure whether or not they both could've been accomplished with just one modification method.
I'm sure Bill has begun to realize the possibilities and will probably get to what he wishes to get done, in due-course.
__ I've included below Bill's related picture, to be viewable in it's entirety here.
Hopeful-Cheers,
-Bob
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PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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wcorey
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Re: On using GM HEI ignition modules
Well I guess I can torment Jordan back because I don't have time ATM to do a detailed explanation or more testing but I can say that what was theorized was correct. The extent of it surprised the hell out 'o me, still trying to absorb and make sense of all I just observed...
Did a real 'quick 'n dirty' fixture, bolted an air die grinder down with the AAU on the end of it and positioned the pickup plate.
Rock solid in one 'polarity' and advances along in a fairly linear fashion in the other, I'd give a very rough guess of about 30-40 degrees total with the one basic setup I tried. No tach set up so I don't know at what rpm all of this was happening but it starts moving at a reasonably slow speed and continues along up to where it's really zinging.
Where everything at the points/cams is happening at half speed, it messes up my perspective when trying to feel my way through this 'seat of the pants' kind of testing. Was operating the air tool with one hand, changing the trigger gap with the other, holding the timing light in my teeth. In the dark because my good xenon timing light has just decided to die so had to use one of those cheapy dim orange lit ones, in my freezing garage...waah...
That 30-40 is point rotor degrees so it's a somewhat extreme result, played around with different gaps but haven't had a chance to test how different magnets, pickups, etc. will alter it. Increasing the gap induced surprisingly little change, until it was at maybe a 1/4" and was on the verge of no longer triggering, where it did have a reducing effect on the overall amount of advance.
At first I had the mechanical AAU functioning and thought the amount of advance seemed large but soon realized the whole unit was advancing, not just the cam portion. I also thought it was retarding rather than advancing because the air tool runs it backward, that had me wondering for a few minutes...
This is all really interesting but about the last thing I need is yet another time draining project, I hope this will spark someone else to jump in here to pursue this further.
Bill
Did a real 'quick 'n dirty' fixture, bolted an air die grinder down with the AAU on the end of it and positioned the pickup plate.
Rock solid in one 'polarity' and advances along in a fairly linear fashion in the other, I'd give a very rough guess of about 30-40 degrees total with the one basic setup I tried. No tach set up so I don't know at what rpm all of this was happening but it starts moving at a reasonably slow speed and continues along up to where it's really zinging.
Where everything at the points/cams is happening at half speed, it messes up my perspective when trying to feel my way through this 'seat of the pants' kind of testing. Was operating the air tool with one hand, changing the trigger gap with the other, holding the timing light in my teeth. In the dark because my good xenon timing light has just decided to die so had to use one of those cheapy dim orange lit ones, in my freezing garage...waah...
That 30-40 is point rotor degrees so it's a somewhat extreme result, played around with different gaps but haven't had a chance to test how different magnets, pickups, etc. will alter it. Increasing the gap induced surprisingly little change, until it was at maybe a 1/4" and was on the verge of no longer triggering, where it did have a reducing effect on the overall amount of advance.
At first I had the mechanical AAU functioning and thought the amount of advance seemed large but soon realized the whole unit was advancing, not just the cam portion. I also thought it was retarding rather than advancing because the air tool runs it backward, that had me wondering for a few minutes...
This is all really interesting but about the last thing I need is yet another time draining project, I hope this will spark someone else to jump in here to pursue this further.
Bill
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DewCatTea-Bob
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- Joined: Sun Nov 01, 2009 10:53 am
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Re: On using GM HEI ignition modules
____ Here I'm now offering my thoughts summarizing what I think this latest post by Bill is indicating.....
" but I can say that what was theorized was correct. "
____ Gather that the trigger-point will indeed advance with increased RPM, and by more than just a minimal amount of degrees.
" Rock solid in one 'polarity' and advances along in a fairly linear fashion in the other, "
____ Just as Jordan had been concerned with, with the pick-up's wire-connections reverse-switched, ya either get a completely static set timing-position (with no variance), or else, an auto-advancing progressive timing,, (similar to that which Jordan's posted graph indicates).
" I'd give a very rough guess of about 30-40 degrees total with the one basic setup I tried. "
_____ With Bill's hastily thrown-together test set-up (out in the cold), he has had to guestimate the amount of "total" advance to be as high as 40-degrees.
__ However, I'm left wondering as to exactly how much of that total is due to the (unknown)- mechanical-AAU (which he mentioned he had mounted & used), and about how much of that total advance is due to the (expected/unexpected) auto.advance effect of the rotor-magnet/pick-up ??
" I don't know at what rpm all of this was happening but it starts moving at a reasonably slow speed and continues along up to where it's really zinging. "
____ I'm gathering that the combo of advance-methods working simultaneously together, start-out advancing relatively moderately but up towards the highest (tested) RPMs, the rate of advance-rate really comes-to-life & progresses upward more rapidly (to the limit). (?)
" Where everything at the points/cams is happening at half speed, "
____ Which raises the question as to whether the "30-40 degrees" is at the AAU, or already converted to that which could be expected with respect to the crankshaft. (?)
" in my freezing garage...waah..."
____ So sorry for that ! _ Had assumed that your nice set-up was in a (fairly-warm) basement.
" That 30-40 is point rotor degrees so it's a somewhat extreme result "
____ Aaahh, I see then... That thus means that the actual-advance total (at the crankshaft) would be way-up near 80-degrees (which is indeed overly "extreme") ! _ So thus that should then be the 'TOTAL' effect of BOTH advance-methods combined together !?
" played around with different gaps but haven't had a chance to test how different magnets, pickups, etc. will alter it. Increasing the gap induced surprisingly little change, until it was at maybe a 1/4" and was on the verge of no longer triggering, where it did have a reducing effect on the overall amount of advance. "
____ Seems reasonable then that perhaps the chosen trigger-magnet was considerably overly strong for the chosen pick-up's sensor !?
__ Ought to be worth trying that gap-testing again with the weakest piece of magnet that's on-hand.
" At first I had the mechanical AAU functioning and thought the amount of advance seemed large but soon realized the whole unit was advancing, not just the cam portion. "
____ So after the test had (prematurely?) reached what should've been the outer-limit of the mechanical-AAU, it was then realized that the amount of advance was still continuing further onward, (evidently due to the other auto.advancing effect).
" I also thought it was retarding rather than advancing because the air tool runs it backward, that had me wondering for a few minutes... "
____ That's a pretty-important point, and still has ME wondering ! ...
I would've expected that the test would be done only with a rotation-device that turns the test AAU in the correct (clockwise) direction, as otherwise a Duke-AAU would indeed RETARD (rather than advance) the timing !
__ So this possibility now thus leads to the question as to perhaps what the actual reason was for why the advance-rate started-out relatively moderate, and then built-up to "really zinging" more quickly upward. ...
So if so, then it must be that the mechanical-AAU was actually fighting-against the forward progress of the (other method of) forward-advance, in actual opposition until the mechanical-AAU became topped-out and the other advance-method could then really TAKE-OFF and begin moving the advance-rate full-speed ahead unopposed !
__ Can you confirm whether or not this possibility was indeed actually occurring ?
" This is all really interesting but about the last thing I need is yet another time draining project, "
____ But Bill, YOU're The MAN !
What could possibly be more fun (this time of year) than to spend your time on this kind of stuff, such as this fun testing!? - (Got a couple of PB-Bunnies pestering you?) - Whatever, better not tell us, I guess, (cuz we wouldn't care to learn that your priority might be some kind of winter-sport or something else totally less interesting than anything to do with DUKEs).
____ It's too bad that Jordan and/or I aren't neighbors with you, cuz then we could have all sorts of fun testing all these sort of things you've been doing !!
Hopeful-Cheers,
DCT-Bob
" but I can say that what was theorized was correct. "
____ Gather that the trigger-point will indeed advance with increased RPM, and by more than just a minimal amount of degrees.
" Rock solid in one 'polarity' and advances along in a fairly linear fashion in the other, "
____ Just as Jordan had been concerned with, with the pick-up's wire-connections reverse-switched, ya either get a completely static set timing-position (with no variance), or else, an auto-advancing progressive timing,, (similar to that which Jordan's posted graph indicates).
" I'd give a very rough guess of about 30-40 degrees total with the one basic setup I tried. "
_____ With Bill's hastily thrown-together test set-up (out in the cold), he has had to guestimate the amount of "total" advance to be as high as 40-degrees.
__ However, I'm left wondering as to exactly how much of that total is due to the (unknown)- mechanical-AAU (which he mentioned he had mounted & used), and about how much of that total advance is due to the (expected/unexpected) auto.advance effect of the rotor-magnet/pick-up ??
" I don't know at what rpm all of this was happening but it starts moving at a reasonably slow speed and continues along up to where it's really zinging. "
____ I'm gathering that the combo of advance-methods working simultaneously together, start-out advancing relatively moderately but up towards the highest (tested) RPMs, the rate of advance-rate really comes-to-life & progresses upward more rapidly (to the limit). (?)
" Where everything at the points/cams is happening at half speed, "
____ Which raises the question as to whether the "30-40 degrees" is at the AAU, or already converted to that which could be expected with respect to the crankshaft. (?)
" in my freezing garage...waah..."
____ So sorry for that ! _ Had assumed that your nice set-up was in a (fairly-warm) basement.
" That 30-40 is point rotor degrees so it's a somewhat extreme result "
____ Aaahh, I see then... That thus means that the actual-advance total (at the crankshaft) would be way-up near 80-degrees (which is indeed overly "extreme") ! _ So thus that should then be the 'TOTAL' effect of BOTH advance-methods combined together !?
" played around with different gaps but haven't had a chance to test how different magnets, pickups, etc. will alter it. Increasing the gap induced surprisingly little change, until it was at maybe a 1/4" and was on the verge of no longer triggering, where it did have a reducing effect on the overall amount of advance. "
____ Seems reasonable then that perhaps the chosen trigger-magnet was considerably overly strong for the chosen pick-up's sensor !?
__ Ought to be worth trying that gap-testing again with the weakest piece of magnet that's on-hand.
" At first I had the mechanical AAU functioning and thought the amount of advance seemed large but soon realized the whole unit was advancing, not just the cam portion. "
____ So after the test had (prematurely?) reached what should've been the outer-limit of the mechanical-AAU, it was then realized that the amount of advance was still continuing further onward, (evidently due to the other auto.advancing effect).
" I also thought it was retarding rather than advancing because the air tool runs it backward, that had me wondering for a few minutes... "
____ That's a pretty-important point, and still has ME wondering ! ...
I would've expected that the test would be done only with a rotation-device that turns the test AAU in the correct (clockwise) direction, as otherwise a Duke-AAU would indeed RETARD (rather than advance) the timing !
__ So this possibility now thus leads to the question as to perhaps what the actual reason was for why the advance-rate started-out relatively moderate, and then built-up to "really zinging" more quickly upward. ...
So if so, then it must be that the mechanical-AAU was actually fighting-against the forward progress of the (other method of) forward-advance, in actual opposition until the mechanical-AAU became topped-out and the other advance-method could then really TAKE-OFF and begin moving the advance-rate full-speed ahead unopposed !
__ Can you confirm whether or not this possibility was indeed actually occurring ?
" This is all really interesting but about the last thing I need is yet another time draining project, "
____ But Bill, YOU're The MAN !
What could possibly be more fun (this time of year) than to spend your time on this kind of stuff, such as this fun testing!? - (Got a couple of PB-Bunnies pestering you?) - Whatever, better not tell us, I guess, (cuz we wouldn't care to learn that your priority might be some kind of winter-sport or something else totally less interesting than anything to do with DUKEs).
____ It's too bad that Jordan and/or I aren't neighbors with you, cuz then we could have all sorts of fun testing all these sort of things you've been doing !!
Hopeful-Cheers,
DCT-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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Jordan
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Re: On using GM HEI ignition modules
Bravo, Bill.
I can just see you with your hands and teeth full of tools, cables and airlines, trying to make adjustments and take readings with things whizzing around.
(addit)
Jokes aside, this could be seriously useful info to someone wanting to DIY with electronic ignition.
Further tests would be needed to find out how different inductive pickups interact with a given ignition unit, be it HEI, CDI or whatever. Maybe winding a custom pickup coil is needed, to get the desired advance curve. Electronics hobbyists used to do it by hand or by using a lathe with turn counter.
Playing "mad scientist" can be fun in itself. I once wanted to make a snail cam reluctor for a bench test, but ended up using a snail cam rear axle chain adjuster from an old British bike - worked perfectly.
As Bill's test showed that more revs made more volts (naturally - it's a permanent magnet generator) it does bring up the question of too much advance at high revs? Still, many machines seemed to do OK with this system. I notice that some bikes (Honda CT110) that use CDI with inductive pickup, use mechanical advance units, maybe for better control of the curve?
Jordan
I can just see you with your hands and teeth full of tools, cables and airlines, trying to make adjustments and take readings with things whizzing around.
(addit)
Jokes aside, this could be seriously useful info to someone wanting to DIY with electronic ignition.
Further tests would be needed to find out how different inductive pickups interact with a given ignition unit, be it HEI, CDI or whatever. Maybe winding a custom pickup coil is needed, to get the desired advance curve. Electronics hobbyists used to do it by hand or by using a lathe with turn counter.
Playing "mad scientist" can be fun in itself. I once wanted to make a snail cam reluctor for a bench test, but ended up using a snail cam rear axle chain adjuster from an old British bike - worked perfectly.
As Bill's test showed that more revs made more volts (naturally - it's a permanent magnet generator) it does bring up the question of too much advance at high revs? Still, many machines seemed to do OK with this system. I notice that some bikes (Honda CT110) that use CDI with inductive pickup, use mechanical advance units, maybe for better control of the curve?
Jordan
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DewCatTea-Bob
- Posts: 2897
- Joined: Sun Nov 01, 2009 10:53 am
- Location: Near SE side of Lake Michigan
Re: On using GM HEI ignition modules
" Maybe winding a custom pickup coil is needed, to get the desired advance curve. "
____ I don't think any particular 'advance-curve' would be of any actually notable advantage, any manor of getting from the static-timing setting at start-up, to the desired full-advance after the engine is running, should suit our DUKEs, well enough.
__ However since it seems that different pick-up units probably influence test-results, we should all wish to choose the same magnet-trigger & pick-up that we KNOW the test-results of. _ Otherwise I'd choose to use the component-parts of a 4-stroke single such as a Honda XL250/350.
" As Bill's test showed that more revs made more volts
it does bring up the question of too much advance at high revs?
____ Yeah at this point there is still some confusion concerning whether his results were actually with the two advance methods working together (in the same forward direction), or in opposition (& thus the mechanical-method somewhat canceling the other).
Either way, Bill's test-results seem to indicate extreme auto-advance range !
" I notice that some bikes (Honda CT110) that use CDI with inductive pickup, use mechanical advance units, maybe for better control of the curve? "
____ That would seem to have to be the case.
__ And as I've stated in another past thread touching on the topic, I myself don't much care for non-mechanical means of ign.advancing.
Hopeful-Cheers,
-Bob
____ I don't think any particular 'advance-curve' would be of any actually notable advantage, any manor of getting from the static-timing setting at start-up, to the desired full-advance after the engine is running, should suit our DUKEs, well enough.
__ However since it seems that different pick-up units probably influence test-results, we should all wish to choose the same magnet-trigger & pick-up that we KNOW the test-results of. _ Otherwise I'd choose to use the component-parts of a 4-stroke single such as a Honda XL250/350.
" As Bill's test showed that more revs made more volts
it does bring up the question of too much advance at high revs?
____ Yeah at this point there is still some confusion concerning whether his results were actually with the two advance methods working together (in the same forward direction), or in opposition (& thus the mechanical-method somewhat canceling the other).
Either way, Bill's test-results seem to indicate extreme auto-advance range !
" I notice that some bikes (Honda CT110) that use CDI with inductive pickup, use mechanical advance units, maybe for better control of the curve? "
____ That would seem to have to be the case.
__ And as I've stated in another past thread touching on the topic, I myself don't much care for non-mechanical means of ign.advancing.
Hopeful-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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Jordan
- Posts: 1469
- Joined: Fri Dec 24, 2010 11:29 am
Re: On using GM HEI ignition modules
____ I don't think any particular 'advance-curve' would be of any actually notable advantage, any manor of getting from the static-timing setting at start-up, to the desired full-advance after the engine is running, should suit our DUKEs, well enough.
I don't agree on that, Bob. With the wrong pickup, you might set the advance to be spot on, then find the retarded firing point is too far out. It's not an easy matter like restricting a mechanical adv-ret unit's bobweights' movement. But then again, for all I know all inductive pickups have pretty much the same characteristics, or is that hoping for too much?
__ However since it seems that different pick-up units probably influence test-results, we should all wish to choose the same magnet-trigger & pick-up that we KNOW the test-results of.
The pickup doesn't know when to trigger the ignition by itself. The electronics in the ignition unit plays its part, according to what voltage it's designed to fire at. It's probable that different ignition units have different trigger voltages. So, if mixing and matching parts, there's still the problem of ascertaining whether what you have will do the job. As I have a Motoplat with a sick ignition unit/coil (I think), I'm hoping that it can be replaced with a set from another bike, while keeping the Motoplat pickup.
Jordan
I don't agree on that, Bob. With the wrong pickup, you might set the advance to be spot on, then find the retarded firing point is too far out. It's not an easy matter like restricting a mechanical adv-ret unit's bobweights' movement. But then again, for all I know all inductive pickups have pretty much the same characteristics, or is that hoping for too much?
__ However since it seems that different pick-up units probably influence test-results, we should all wish to choose the same magnet-trigger & pick-up that we KNOW the test-results of.
The pickup doesn't know when to trigger the ignition by itself. The electronics in the ignition unit plays its part, according to what voltage it's designed to fire at. It's probable that different ignition units have different trigger voltages. So, if mixing and matching parts, there's still the problem of ascertaining whether what you have will do the job. As I have a Motoplat with a sick ignition unit/coil (I think), I'm hoping that it can be replaced with a set from another bike, while keeping the Motoplat pickup.
Jordan
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wcorey
- Posts: 323
- Joined: Sun Jan 31, 2010 1:50 am
- Location: MA USA
Re: On using GM HEI ignition modules
Sorry for the hit and run post, didn't have time for more but thought it too good to hold out.
Still haven't had a chance to do any more with it but I can clarify a couple things.
The mechanical advance unit is being used on the fixture, however once I knew advance was being produced by the pickup I put a cable tie around the AAU to hold it closed. The amount of advance does seem to be well in excess of 30 degrees at the point cam from the pickup alone, meaning 60+ at the crank. I need to scribe some degree marks on the pickup mounting plate to get a solid number.
Advance seemed to 'top out' at a high rpm (and got there at a very linear rate) so to emulate the stock advance 'curve' (that goes up fairly quickly then levels off through most of the operating range) may be a problem also.
It would appear that I have to cut the voltage in half or more, as it's easy/quick I may try a few resistor combinations to see if it can be reined in that way. Next easiest would be a weaker magnet, then a stationary magnet with a slotted steel plate or cup rotating between it and the pickup and I can vary the slot widths. I also want to try the other style pickup with the built in magnet. Yes, a coil with half the number of windings would be a viable option but I'm not going there. Could try a voltage regulator like an LM317 but that may only limit the max voltage and not change the threshold point anyway.
At some point the voltage at kickstart rpm's may become too low to trigger the HEI.
Then to get serious I need a tachometer to nail down exactly where everything is happening. And to fix my good timing light so I don't need to work in the dark...
Seeing how there is an adequately functioning AAU designed into the stock system, it would seem somewhat pointless to bother with this unless some specific specialized result is needed. Plus I have other tricks up my sleeve and may not use any of this, the HEI, pickup or AAU.
Very good to know that the pickup is polarity sensitive though so as to avoid a dangerous amount of advance if wires got switched around.
I'm sure curiosity will get me to play with it some more but I have no plans on pursuing it with much depth, just too many other things competing for my time and effort.
Bill
Still haven't had a chance to do any more with it but I can clarify a couple things.
The mechanical advance unit is being used on the fixture, however once I knew advance was being produced by the pickup I put a cable tie around the AAU to hold it closed. The amount of advance does seem to be well in excess of 30 degrees at the point cam from the pickup alone, meaning 60+ at the crank. I need to scribe some degree marks on the pickup mounting plate to get a solid number.
Advance seemed to 'top out' at a high rpm (and got there at a very linear rate) so to emulate the stock advance 'curve' (that goes up fairly quickly then levels off through most of the operating range) may be a problem also.
It would appear that I have to cut the voltage in half or more, as it's easy/quick I may try a few resistor combinations to see if it can be reined in that way. Next easiest would be a weaker magnet, then a stationary magnet with a slotted steel plate or cup rotating between it and the pickup and I can vary the slot widths. I also want to try the other style pickup with the built in magnet. Yes, a coil with half the number of windings would be a viable option but I'm not going there. Could try a voltage regulator like an LM317 but that may only limit the max voltage and not change the threshold point anyway.
At some point the voltage at kickstart rpm's may become too low to trigger the HEI.
Then to get serious I need a tachometer to nail down exactly where everything is happening. And to fix my good timing light so I don't need to work in the dark...
Seeing how there is an adequately functioning AAU designed into the stock system, it would seem somewhat pointless to bother with this unless some specific specialized result is needed. Plus I have other tricks up my sleeve and may not use any of this, the HEI, pickup or AAU.
Very good to know that the pickup is polarity sensitive though so as to avoid a dangerous amount of advance if wires got switched around.
I'm sure curiosity will get me to play with it some more but I have no plans on pursuing it with much depth, just too many other things competing for my time and effort.
Bill
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DewCatTea-Bob
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- Location: Near SE side of Lake Michigan
Varying Advance-Curves & Varying PickUps
By: Jordan...
" I don't agree on that, Bob. "
____ I don't get whatever you mean by "that", Jordan... As (in the same paragraph) you continued-on with follow-up comment-points which are not actually pertinent to my specific point I had made (in my paragraph which you placed above your comment). ...
__ My intended point had been that the 'curve' of the advance-rate (from static to full-advance), need not be any particular form, in order to get the job done (well enough).
For instance, I'm meaning to proclaim that there's no big/notable advantage between having the AAU's advance-rate climb linearly (or any non-linear rate) from the static-timing point up-to full-advance, between 0 & 3k RPM (as is normal), or (at an extreme), having the advance-rate jump from static to full-advance, between 1999 & 2001 RPM -(for just an example). _ Any difference in engine-power (between ANY such [even radically] different advance-curves), is nothing that would make any noteworthy change.
__ Now with my intended-point thus extended, if you still "don't agree", please follow-up with wording that ADDRESSES that claim of mine. _ As I'm willing to be convinced otherwise.
(If you really do disagree, you'd not be the only one who thinks the 'curve' matters.)
" The pickup doesn't know when to trigger the ignition by itself. The electronics in the ignition unit plays its part, according to what voltage it's designed to fire at. It's probable that different ignition units have different trigger voltages. So, if mixing and matching parts, there's still the problem of ascertaining whether what you have will do the job. "
____ Sorry Jordan, as I had neglected to include wording to confirm that I had been in regards to the HEI-module specifically.
" As I have a Motoplat with a sick ignition unit/coil (I think), I'm hoping that it can be replaced with a set from another bike, while keeping the Motoplat pickup. "
____ What's meant by "a set from another bike" , exactly?
__ I'm thinking your current ignition set-up could be simply replaced with a HEI-module and perhaps another (regular-type) ign.coil.
You'd then just need to use a strobe-light to check that your ign.timing is still made correct.
__ The HEI-module seems (to me) to be more-or-less merely the electronics needed to allow a small trigger-current to control the flow of the larger primary-current (which excites the ign.coil).
Hopeful-Cheers,
-Bob
" I don't agree on that, Bob. "
____ I don't get whatever you mean by "that", Jordan... As (in the same paragraph) you continued-on with follow-up comment-points which are not actually pertinent to my specific point I had made (in my paragraph which you placed above your comment). ...
__ My intended point had been that the 'curve' of the advance-rate (from static to full-advance), need not be any particular form, in order to get the job done (well enough).
For instance, I'm meaning to proclaim that there's no big/notable advantage between having the AAU's advance-rate climb linearly (or any non-linear rate) from the static-timing point up-to full-advance, between 0 & 3k RPM (as is normal), or (at an extreme), having the advance-rate jump from static to full-advance, between 1999 & 2001 RPM -(for just an example). _ Any difference in engine-power (between ANY such [even radically] different advance-curves), is nothing that would make any noteworthy change.
__ Now with my intended-point thus extended, if you still "don't agree", please follow-up with wording that ADDRESSES that claim of mine. _ As I'm willing to be convinced otherwise.
(If you really do disagree, you'd not be the only one who thinks the 'curve' matters.)
" The pickup doesn't know when to trigger the ignition by itself. The electronics in the ignition unit plays its part, according to what voltage it's designed to fire at. It's probable that different ignition units have different trigger voltages. So, if mixing and matching parts, there's still the problem of ascertaining whether what you have will do the job. "
____ Sorry Jordan, as I had neglected to include wording to confirm that I had been in regards to the HEI-module specifically.
" As I have a Motoplat with a sick ignition unit/coil (I think), I'm hoping that it can be replaced with a set from another bike, while keeping the Motoplat pickup. "
____ What's meant by "a set from another bike" , exactly?
__ I'm thinking your current ignition set-up could be simply replaced with a HEI-module and perhaps another (regular-type) ign.coil.
You'd then just need to use a strobe-light to check that your ign.timing is still made correct.
__ The HEI-module seems (to me) to be more-or-less merely the electronics needed to allow a small trigger-current to control the flow of the larger primary-current (which excites the ign.coil).
Hopeful-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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Jordan
- Posts: 1469
- Joined: Fri Dec 24, 2010 11:29 am
Re: Varying Advance-Curves & Varying PickUps
Hi Bob,
As long as the 2 important ignition points can be achieved for advance and retard at specified revs, I agree with you that the actual shape of the curve doesn't matter much. I think that's what you're saying?
To fix my Motoplat ignition, I'm intending to try a CDI "black box" from say a Japanese bike, or chainsaw - whatever comes to hand, and a coil made for CDI - again probably from a Japanese bike.
High Energy Ignition (HEI) is an enhanced performance ignition. The term is given to a type that uses dwell-extension by electronic control. It makes the dwell (the time the ignition coil has to charge) independent of engine speed, and has a variable mark-space ratio. That's supposed to help keep ignition power up at high revs, which otherwise would have progressively shorter time to charge the coil.
See datasheet: http://www.datasheetarchive.com/MC3334-datasheet.html "High Energy Ignition Circuit".
Probably useful for sporty V8's, but it's not something I need for my bike, and requires a battery I think. I'm gonna ditch the battery, as it's not needed with self-generating CDI ignitions like on Ducatis.
Jordan
As long as the 2 important ignition points can be achieved for advance and retard at specified revs, I agree with you that the actual shape of the curve doesn't matter much. I think that's what you're saying?
To fix my Motoplat ignition, I'm intending to try a CDI "black box" from say a Japanese bike, or chainsaw - whatever comes to hand, and a coil made for CDI - again probably from a Japanese bike.
High Energy Ignition (HEI) is an enhanced performance ignition. The term is given to a type that uses dwell-extension by electronic control. It makes the dwell (the time the ignition coil has to charge) independent of engine speed, and has a variable mark-space ratio. That's supposed to help keep ignition power up at high revs, which otherwise would have progressively shorter time to charge the coil.
See datasheet: http://www.datasheetarchive.com/MC3334-datasheet.html "High Energy Ignition Circuit".
Probably useful for sporty V8's, but it's not something I need for my bike, and requires a battery I think. I'm gonna ditch the battery, as it's not needed with self-generating CDI ignitions like on Ducatis.
Jordan
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