modules that retard....
drove 5 hours last night plenty of time to think
if you have a window of time in which to make a spark
and you have a minimum time set in the module that the coil must be on to do that properly,
the faster you go the later the spark will be... i.e the fixed window of time for filling the coil is pushing out the window of time you have for actually getting the spark away, then yes i can imagine some impact on timing
what it has to do at 6000 rpm differs from 1000 rpm.
this would normally be catered for in the mechanical advance curve.... more mechanical advance to mask the retard of the module.
the minimum dwell problem can be addressed by coil winding and higher current into the coil, provided the module is designed to take advantage. like mopar did with the Race ignition boxes chrome and gold etc.. they made them very good at high rpm but not so good driving to the shops and they did it by reducing the resistance in the primary circuit, bigger current, shorter time to "full". Used a special ballast resistor a specific coil and some tweaking of component values in the box...
the only time this would be an issue is if you are using the set-up way out of bounds
i.e you lock off the distributor and run say 28* across the rpm range and hope to spin it to 7K, you have then removed a vital part of the system.
you have no advance curve therefore are totally beholden to the modules ability to switch... i think you would see what Turk sees to a greater or lesser extent
the setup was not designed for that, it doesn't make the ignition module ****. it just means you have removed part of the system that was useful, i.e all or most of the mechanical advance, and that has exposed one of the limitations of the chosen module
the weights, their shape, their hinge point the position the springs attach to the advance mechanism are all going to play a part, as soon as the weights swing out the forces on them are different
so a 10 rpm change at 1000 rpm and a 10 rpm change at 4000 rpm can produce a different changes in advance regardless of spring or spring loop config.
so one presumes if the module looses 6 degrees between 1000 rpm and 5000 rpm the advance weight and spring set up is adding that, along with what we think of as our prescribed advance curve to keep everything on track.
in that situation you would want to distributor to pull in 3* of distributor advance over that range to stand still.... totally locked out is not an option
On the type of motor where you would conceivably want to run ignition advance that is pure "drag race" a crank trigger a cam sensor or similar and programmable ECU are the way to go
basic:- megajolt with ford EDIS and multi coil wasted spark
great:- locked distributor and daytona sensors cd1
no more problems and rock solid ignition timing.
so if you put all of your money into making a motor that will be the talk of the track
using a street/oem ignition makes no sense, you threw away everything OEM apart from the engine block, id suggest the ignition needs to go and be replaced as well.
now if you were observing this issue on a car which actually has a mechanical advance curve then my initial response about the module being wired backwards carries some merit.
Dave
That’s a pretty good summation of it. Here’s the issue.
All and I mean ALL ignition systems other than points will retard with rpm. All of them. Even the Unilite will retard some with rpm when used as a stand alone ignition.
If you know when and how much the retard is, you can work up a mechanical curve that accounts for it. More on this in a bit.
The issue is when, as you said the advance mechanism is locked out. Whatever the retard is affects the timing. In essence if you lock out the advance, you will have a regressive timing curve. From my experience, there are no combustion chambers that want a regressive curve.
Engines want less timing at and around peak torque and more timing at and around peak power. I shouldn’t have to explain that so I won’t.
If the advance is locked you end up compromising torque and power. You’d think for all the wailing and gnashing of teeth around here by the the guys who turn less than 6k and who worship at the brazen alter of torque they would do all they can to not kill torque.
But that’s exactly what happens. Every single time.
To follow this further down the rabbit hole, if the advance is “all in” by some arbitrary rpm line 2500 or even 3500 rpm, you are loading the engine with all that timing at and around peak torque where it doesn’t want it.
Now you get all kinds of detonation issues going so you reduce your total and it helps with detonation but now when you do get your foot in it the engine is a pig. It wants more timing at peak power but you don’t have it because it’s all in too early and you compromise both torque and power.
Yet the argument continues on apace for quick timing curves or locked out advance. And the defenders of this nonsense are dogmatic about it.
I once WAS one of those guys who lived quick curves or even locking them out. That was because I, at that time WAS ignorant of it.
Thankfully a guy called me out on it and showed me my errors. I didn’t better him. I watched his videos showing it happening. I didn’t just sit back in my ignorance and carry on. I went and bought a distributor test bench for my own use.
And I will spend the REST OF MY LIFE working to correct my horrible, horrendous advice in addition places like this where I gave bad advice.
That’s why I’m so damned dogmatic about it. I was dead wrong and I screw many guys with bad advice. For that I’m ashamed.
To that end if it means I have to trash slow thinking, pig headed, arrogant clowns like Bewy and George jetson to expose their ignorance and unwillingness to even CONSIDER they could maybe, potentially might be dead wrong and giving bad advice then so be it.
I deserve that for the bad advice I’ve given over the years.
If one or two guys come along and test what I’m saying and prove it out and fix their engines and gain the benefits of what I’m now saying then I’ve at least corrected a very minute bit of what I had wrong.
