Can a Durspark Distributor/Module do this....

[Wolverine]

There are statements regarding a feature of the Duraspark distributor/module I do not understand.

The statement is that when cranking the motor to start it, the "module" is smart enough to know the engine is being cranked, and is able to retard the ignition timing. The retardation number varies from 2 to 8 degrees.

Is this in fact a true statement?

If it is, can someone tell me how the module can change the relationship between the rotor and the distributor cap in order to retard the timing? I can find no mechanism the module has that will allow it to retard the timing when just cranking the motor.

The module does not determine when to spark. The module determines when to charge the coil.

Am I missing something?

 

[Mikes73]

Here are the basics of Ford Duraspark igniton. It is very reliable, put it on the foxbody a few years ago and haven't touched it.

http://www.mustangsteve.com/conversion.html

 

[Wolverine]

Here are the basics of Ford Duraspark igniton. It is very reliable, put it on the foxbody a few years ago and haven't touched it.

http://www.mustangsteve.com/conversion.html

I see how it senses the starter is cranking, by sensing voltage out the S terminal of the starter solenoid. This 12V output was used to give the coil extra juice when the engine was starting to give a temporary better spark. But there is nothing that shows how the module is able to turn the distributor plate, which is the only way the spark timing can be adjusted.

To prove the point, check your timing with the engine running. Run/jump 12VDC to the white wire temporarily so the module thinks you are starting the car. Check the timing to see if it moves. Then remove the 12VDC jumper and see if the timing goes back to where it started. If the timing is moving, you should be able to see the 4-8 degrees very easily.

 

[Mikes73]

I've done some experimenting with the white wire by disconnecting it when then engine was fully heat soaked, tried cranking on the engine with 16* base timing on my 351w and got major starter lag. Reconnected the white wire immediately afterward and it turned over with no lag and fired right up. I think what the duraspark box does is delays the spark in a sense with the white wire connected in crank mode only :-}

 

[Wolverine]

I've done some experimenting with the white wire by disconnecting it when then engine was fully heat soaked, tried cranking on the engine with 16* base timing on my 351w and got major starter lag. Reconnected the white wire immediately afterward and it turned over with no lag and fired right up. I think what the duraspark box does is delays the spark in a sense with the white wire connected in crank mode only :-}

Think about when your engine sparks. The engine sparks when the rotor is under the distributor cap contact. If the module does not control the physical location of the rotor in relationship to the distributor cap, it cannot control the spark. The coil will let loose with it's power when the voltage it is holding is able to overcome the resistance for the voltage it is holding- when the rotor is under the contact.

It is not my intent to be a pain on this subject. You may have a better startup with the Duraspark module. But it will not be because of the timing of the spark.

If you really want to test it(don't do this for an extended period. Electronic ignitions don't like holding the spark for non firing systems):

1. Except for the coil to distributor ignition wire(Center cap wire) and #1 plug wire, remove all ignition plug wires at the distributor.

2. Hook up the spark plug end of the #1 ignition wire to a grounded spark plug(ground the thread or bent over tip end with a test lead).

3. Hook up a timing light. Hook up dwell meter if you have one.

4. Crank motor, check timing & dwell. Engine will crank, and the spark plug should spark giving you a timing light pulse.

5. Remove/install white wire.

6. Crank motor, check timing & dwell.

What is the difference?

Would you agree the ignition timing can only change by rotating the distributor or the distributor plate as the centrifugal advance and vacuum advance do? If not, then we need to delve into this more because we certainly have a different understanding of the ignition system.

 

[Jeff73Mach1]

No I don't agree

Off the top of my head and with no promise as to accuracy, i start with this line of reasoning.

Consider that a locked distributor with no advance can be used with a box to provide advance and retard. In this instance, the ignition module is the box. The spark fires when the signal is received.

With points this was done my physically opening and closing the points to trigger the coil to fire. When using an electronic module the trigger to fire is the electronic module/brain box and the cap and rotor relationship does not change, but a rotor is passing a cap terminal for the width of the contact on the rotor + the width of the contact on the cap terminal. A spark can jump a bit before or after the contacts pass say another 15 thousandths. Therefore, without changing rotor to cap relationship, there is quite a bit of ignition timing advance or delay that is still available through the marvel of modern electronics.

of course I am a lawyer, what do I know?

 

[TheRktmn]

No I don't agree

Off the top of my head and with no promise as to accuracy, i start with this line of reasoning.

Consider that a locked distributor with no advance can be used with a box to provide advance and retard. In this instance, the ignition module is the box. The spark fires when the signal is received.

With points this was done my physically opening and closing the points to trigger the coil to fire. When using an electronic module the trigger to fire is the electronic module/brain box and the cap and rotor relationship does not change, but a rotor is passing a cap terminal for the width of the contact on the rotor + the width of the contact on the cap terminal. A spark can jump a bit before or after the contacts pass say another 15 thousandths. Therefore, without changing rotor to cap relationship, there is quite a bit of ignition timing advance or delay that is still available through the marvel of modern electronics.

of course I am a lawyer, what do I know?

+1

You beat me to it. I was thinking that the extra wide rotor contact surface allows the ignition box to fire along more degrees of rotation that the old skinny points type rotors. Another reason that the second gen Duraspark caps have a larger diameter with more spacing between wire towers (to allow for the wide rotor to cap contact area).

 

[Wolverine]

Good. You believe the module controls the timing output of the coil.

Here is a quick field test for you:

1. You need a timing light and a test lead.

2. Remove the ignition wire at the center of your distributor cap.

3. Clip one end of your test lead to the end of this ignition wire and the other test lead end to a good ground.

4. Engage your timing light pickup to this ignition wire.

5. Crank engine. Observe timing light. (Hope you have a good battery...if not, better to find out now than in February with 10" of snow on the ground).

If you are correct, when cranking the engine, you will see the timing light flash. The pause in between is time which the module is keeping the coil from firing.

If you don't see a flash, it is because the coil is always grounded, and always dissipating it's energy.

The only thing preventing the coil from discharging it's energy is the air gap the rotor sees in not being close enough to the distributor contact point. Once the voltage stored in the coil is able to overcome the resistance it sees from the rotor in the cap, zap. The deed is done.

There is nothing preventing the discharge. This would require something between the coil's ignition wire(output at coil top) and the top of the distributor cap. There is clearly nothing there.

I understand the module is kind of a black box. That is part of the problem with buying them. They are not certified to perform in a certain manner. They are not certified in regards to idle dwell, dwell curve, top RPM. Nothing.

However, the timing for your engine is not in a black box. The coil is not.

I hope I am being respectful and this is considered a gentemenly discussion. We are both persistent, and nothing is wrong with that...except that one of us is wrong. At this time I would contend the timing advance is an urban legend. Do the test above and prove me wrong...respectfully, james.


Also, if you could please provide me the name of a manufacturer with a black box(msd, whatever) that is advertised to advance/retard the timing with a fixed distributor cap, fixed advance plate that also has:

1. Rotor

2. Distributor cap.

Look at all that is required of the MSD E-CURVE under the distributor cap. But you can't compare that to what is under your cap.

http://www.msdignition.com/default.aspx?id=15032387510&blogid=429

 

[Totalled]

What's your point? The module retards the timing electronically.

Ford TFI systems have no mechanical advance. It's all computer controlled.

 

[Mikes73]

James not trying to argue or have a big debate :-}. The foxbody is put up for the winter but I may check out your test in the spring lol. The car is an 87 mustang LX with a .030" over 69 351W with a comp cam, headers, crane roller rockers, stealth intake, 750 carb, 2800 stall, 3.73's, professionally ported and polished heads and the tried and true Duraspark II ignition system. It may not be the best but it is reliable and functions very well. I've tweaked the distributer with a recurve kit( full mechanical advance all in @ 2500 rpm), welded the slot to limit total mechanical advance to 20*. So what I am running on it is 15* base (the cam likes this setting best) with 20* total mechanical advance to achieve the 35* total mechanical timing. Vacuum advance is hooked up also to get a little more fuel economy when cruising haha. This car runs very, very strong so I don't think I will be changing anything. Have a good one.

 

[Wolverine]

What's your point? The module retards the timing electronically.

Ford TFI systems have no mechanical advance. It's all computer controlled.

I am just trying to make sure the truth is known regarding the Duraspark module upgrade in a car with a distributor, rotor, mechanical advance, vacuum advance. And, the disputed truth is whether the Duraspark module can advance the timing on the distributor.

In regards to the TFI systems, the timing was computer controlled via digital input from vacuum readings and crankshaft rotor sensors....and there were many issues. So many in fact when those systems broke, people went to the boneyard and pulled out the Duraspark mechanical advance distributors and Duraspark modules from the proper Fords.

James not trying to argue or have a big debate :-}.

I don't mind the long debate. I just haven't seen the relationship that allows the Duraspark system to change the timing.

With points this was done my physically opening and closing the points to trigger the coil to fire. When using an electronic module the trigger to fire is the electronic module/brain box

The points only determine when the coil is being charged. They do not trigger anything to fire. The points have no timing effect on the output timing. None.* Trigger is the word that may be used, but it is not a trigger in regards to output. It is a trigger in regards to input voltage to the coil.

The longer the points are closed(the larger the dwell), the more the coil is fed electrons through the points to the coil - Negative terminal. When the points open electrons can no longer enter the coil. However, the electrons that were moving into the coil have momemtum and kind of squeeze together in the coil. When the rotor gets near the distributor contact, the secondary coil which is now highly charged due to the magnetic field produced by the incoming primary electron get shot out of the coil to the spark plug. The magnetic field collapses and the procedure starts over again.

*None meaning the timing is only changed to compensate for movement in the points. No one checks their timing and then adjusts their points. We adjust the distributor.

 

[Totalled]

And, the disputed truth is whether the Duraspark module can advance the timing on the distributor.

What? Where did that come from? It controls dwell, and can retard the timing though a voltage trigger.

 

[Mikes73]

Wolverine, Duraspark II only uses the timing retard feature during startup only, timing ADVANCE is controlled through mechanical and vacuum funtions of the distributer not the ignition box.

Have a good one.

 

[Wolverine]

Wolverine, Duraspark II only uses the timing retard feature during startup only, timing ADVANCE is controlled through mechanical and vacuum funtions of the distributer not the ignition box.

Have a good one.

Sorry, that is incorrect. Whether the timing is advanced or retarded, the only way to adjust the timing is by rotating the distributor or rotating the timing plate in the distributor.

In a previous post, you mentioned how you adjusted the timing by adjusting the mechanical points. Actually, you cannot adjust the timing by adjusting the points. You are adjusting the dwell angle=amount of time the coil is charging. At a given RPM, a larger dwell angle provides a longer time period to charge the coil.

I agree the white Duraspark wire provides a means of sensing when the engine is starting. But, what it does with that is speculation. It certainly does not change the timing.

If you look at this image:

you will see the only wires to the distributor from the Duraspark are to sense the rotating spokes.

This post/page also mentions how the duraspark retards the timing. Actually, I don't think it retards the timing. I think it may increase the dwell angle to allow more charge to the coil. Or, maybe the duraspark needs a sure 12V to operate at startup.

In any event, run my test in the spring.


Here is a service manual page for the Duraspark:

Here is a link to the image:

http://www.fordmuscleforums.com/attachments/all-ford-techboard/24460d1352821408-duraspark-ii-ignition-retard-fallacy-fiction-duraspark-ii-dual-mode_1.jpg

This page depicts the "special" Duraspark module that can change the timing. The module has a 3rd plug. Additionally, to take advantage of the retard/advance function you will see the modulator in figure 2. This modulator has a vacuum line that runs to the distributor to advance/retard the timing. If your Duraspark II is not "special" and you do not have the modulator, your DII is not advancing/retarding the timing under any conditions.

 

[Mikes73]

Wolverine I reread my postings several times and can't find any reference made to points, it is early here though. You do know Duraspark II is full electronic igniton thus having no points in the distrubuter right

On the timing adjustment issue I stated that adjusments were made to the total available mechanical advance by limiting its travel by welding up the slot underneath the trigger assembly in the distributer. I can custom curve a Duraspark via different spring tensions and can limit maximum total mechanical advance by reducing or opening the slot up by grinding or welding depending on what the case may be. Small block Ford's prefer anywhere from 34* to 36* total mechanical advance at full throttle so that is what I tune for.

Here is a pic of Duraspark distrubuter on my 87 lx's engine

http://s59.beta.photobucket.com/user/mmanns69/media/DCP02151.jpg.html?sort=6&o=3#/user/mmanns69/media/DCP02151.jpg.html?sort=6&o=4&_suid=1352892819202025761916065545154

It isn't no beauty like a 71-73 but here is a pic anyway, or by the way your car is real nice.

http://s59.beta.photobucket.com/user/mmanns69/media/DCP02151.jpg.html?sort=6&o=4#/user/mmanns69/media/DCP02147.jpg.html?sort=6&o=1&_suid=135289309434707367780033207074

Have a good one

 

[TommyK]

Wolverine, Duraspark II only uses the timing retard feature during startup only, timing ADVANCE is controlled through mechanical and vacuum funtions of the distributer not the ignition box.

Have a good one.

Sorry, that is incorrect. Whether the timing is advanced or retarded, the only way to adjust the timing is by rotating the distributor or rotating the timing plate in the distributor.

Can we agree that timing is the relationship between the ignition event and the position of the piston on the power stroke? If so read on.

Don't know for sure but I would theorize that in the case of the duraspark there is a timing circuit in the module which is activated when it sees 12V from the white wire during cranking. This circuit delays the discharge of the coil which normally occurs when the armature and the stator are aligned, to a point after alignment thus changing the relationship of the ignition event to the piston on the power stroke. When the key is released and the module sees running voltage from the red wire the timing goes back to normal. I think this is the basis for how the aftermarket "starter saver" boxes work.

I think I read somewhere that a half tooth misalignment of the armature to the stator equals an 8 degree change in timing.

Or it could be nothing like that.

 

[Wolverine]

Can we agree that timing is the relationship between the ignition event and the position of the piston on the power stroke? If so read on.

Agreed.

Don't know for sure but I would theorize that in the case of the duraspark there is a timing circuit in the module which is activated when it sees 12V from the white wire during cranking.

Disagree with theory for the following reasons.

1. As agreed, timing is the basis for firing of the ignition. Timing is not the basis for charging the coil. Regardless of when the coil is being charged, when the rotor is in close proximity to the distributor cap, it is going to fire.

2. Delaying the start of ignition coil charging is not going to delay the firing of the plug...unless there is so little charge the plug could not be fired. And that would be the result of delaying the start of the coil charge.

3. The higher the compression of the engine, the greater the resistance across the spark plug. As a result, you would expect a higher voltage spark at start up. This would be achieved by starting the charge cycle earlier, not later. Again, the timing of the fire would be based on the relationship between the rotor and the distributor cap.

This circuit delays the discharge of the coil which normally occurs when the armature and the stator are aligned, to a point after alignment thus changing the relationship of the ignition event to the piston on the power stroke. When the key is released and the module sees running voltage from the red wire the timing goes back to normal. I think this is the basis for how the aftermarket "starter saver" boxes work.

Send me a technical spec on a starter saver box and I will review it.

I think I read somewhere that a half tooth misalignment of the armature to the stator equals an 8 degree change in timing.

Or it could be nothing like that.

Warning- Math Calculations

1 Cam rotation = 2 Crankshaft rotations

360 degrees of Camshaft = 720 degrees of Crankshaft

360 degrees of distributor cam = 720 degrees of Crankshaft

(Timing gear is bigger than crankshaft gear)

8 teeth on cam = 720 degrees of crankshaft

1 tooth on cam = 90 degrees of crankshaft.

This is why modern automobiles have CPS(Crankshaft position sensors) on the crank(reduce the large tolerance by 1/2), and then put typically 4 teeth per cylinder. There is also a tooth missing or some other marker to allow the sensor to report top dead center on #1.

 

[Wolverine]

Wolverine I reread my postings several times and can't find any reference made to points, it is early here though.

I was referring to post #6 of this thread,

"With points this was done my physically opening and closing the points to trigger the coil to fire. "

Perhaps this is a misstatement on your part. But, if this is what you believe to be true I challenge you to find me any technical reference stating the purpose of points is to trigger the coil to fire. That is totally inaccurate. The purpose of points is to charge the coil. Nothing to do with the timing of the spark.

You do know Duraspark II is full electronic igniton thus having no points in the distrubuter right

Wrong.

The Duraspark II is not a fully electronic ignition. It is a partial electronic ignition replacing the points only. Full electronic ignitions have no distributor, no rotor, no mechanical points, no mechanical vacuum advance, no mechanical vacuum retard, no mechanical centrifugal advance. (Vacuum retard was an early smog issue. If you ever notice a vacuum advance with 2 hoses, 1 hose was to advance timing, the 2nd hose retarded timing during engine cold conditions).

On the timing adjustment issue I stated that adjusments were made to the total available mechanical advance by limiting its travel by welding up the slot underneath the trigger assembly in the distributer. I can custom curve a Duraspark via different spring tensions and can limit maximum total mechanical advance by reducing or opening the slot up by grinding or welding depending on what the case may be. Small block Ford's prefer anywhere from 34* to 36* total mechanical advance at full throttle so that is what I tune for.

I agree you can custom tune the curve. I look forward to the day when I can install a fully electronic ignition in my Mustang and play with the curves all day long.

But that has nothing to do with the Duraspark retarding the timing. You are making mechanical adjustments/fixes. If you can show me how the Duraspark makes a mechanical adjustment, then I would agree with you.

Before I began challenging the statement the DII retards timing at start conditions, I checked many technical articles regarding the Duraspark. You like the law. I like technical articles. Nowhere have I found any evidence to support this statement. Not in Ford Technical Bulletins, Ford Service Manuals, etc.

Choose the DII because you like whatever features it has to offer. But don't choose it because you believe it retards the timing...it definitely does not do that. I don't know what the DII does with the signal from the white wire, but it definitely does not retard the timing.

And...your fox body car looks fine.

 

[Mikes73]

I concede, you win! - I like to use what works and try not to overthink things :-}


Oh and thanks about the foxbody.

Have a good one.