2.7 with new MSD 8524 and coil - missing badly

[T77911S]

in the pic with the rotor and cap, the cap does not look good. the post for #5? does not look good.

do not use a condensor with the MSD, or bosch.

thats were i mounted mine in my 2.7.

[scarceller]

What shape and how old are the spark wires? Even if they look good they could be breaking down from age. I just had a set of wires that looked perfect in my Mustang 5.0L but upon close inspection at night the wires looked like an electrical octopus laying over the engine! In the dark you could see them arcing and carrying spark over the surface of the rubber! Since you improved spark energy it could be that the wires simply can't contain the extra energy now.

[wwest]

Originally Posted by scarceller

What shape and how old are the spark wires? Even if they look good they could be breaking down from age. I just had a set of wires that looked perfect in my Mustang 5.0L but upon close inspection at night the wires looked like an electrical octopus laying over the engine! In the dark you could see them arcing and carrying spark over the surface of the rubber! Since you improved spark energy it could be that the wires simply can't contain the extra energy now.

SOP, even new wires will exhibit that at night.

[scarceller]

Originally Posted by wwest

SOP, even new wires will exhibit that at night.

In my case they where also arcing over to engine tin in spots, I think that's what you really don't want happening. I also had arcing at the coil output to chassis.

Your saying that seeing the cables light up is not a problem, got it.

[T77911S]

sal, i agree. i said in an earlier post craig bought a new set and his car ran worse. put the old ones back on and it ran better. new ones can be bad too.

west, do you make this crap up as you go along

sounds like OP might have fixed it with the cap. if that does no fix it he needs to look into fuel/mixture and air leaks.

[scarceller]

Here's my personal opinion about ignition:
You really only ever need just enough ignition energy to jump the spark gap. Often folks install way to strong ignition system for the needs of the engine. Not a good idea to over provision the ignition system as it causes a bunch of other issues.
If you are not doing a turbo setup then a simple basic ignition is all you need. Even the factory changed from CDI after the 3.0L. The 84-89 3.2L uses very basic 12vdc old school coil and it's good for 7000RPMs.
Not downing the after market CDI systems, I'm just pointing out that if the stock system can fire the plug and light the mixture you can't really improve things much. Furthermore, these systems that produce 2 sparks back to back are not that beneficial and only mask the real issue, 1 spark needs to do it every time!

[wwest]

Originally Posted by scarceller

In my case they where also arcing over to engine tin in spots, I think that's what you really don't want happening. I also had arcing at the coil output to chassis.

Your saying that seeing the cables light up is not a problem, got it.

In complete darkness the new HV wiring on my LS400 has the look of St. Elmo's "fire" off the wing tips of a KC-97, Fuzzy glow here and there, NOT an ARC.

"coil out put to chassis"

I have seen this, but only with the HV wire to the distributor removed. If that happens otherwise there is a open, high resistance between the coil and the spark plug, or a gap to wide to jump.

Or even to much pressure in the cylinder...FI.

[wwest]

Originally Posted by T77911S

sal, i agree. i said in an earlier post craig bought a new set and his car ran worse. put the old ones back on and it ran better. new ones can be bad too.

west, do you make this crap up as you go along

No, just a broader experience base then others, apparently.

sounds like OP might have fixed it with the cap. if that does no fix it he needs to look into fuel/mixture and air leaks.

air leaks...???

[wwest]

Originally Posted by scarceller

Here's my personal opinion about ignition:
You really only ever need just enough ignition energy to jump the spark gap. Often folks install way to strong ignition system for the needs of the engine. Not a good idea to over provision the ignition system as it causes a bunch of other issues.
If you are not doing a turbo setup then a simple basic ignition is all you need. Even the factory changed from CDI after the 3.0L.

The 84-89 3.2L uses very basic 12vdc old school coil and it's good for 7000RPMs.

Not quite the case....

Not downing the after market CDI systems, I'm just pointing out that if the stock system can fire the plug and light the mixture you can't really improve things much. Furthermore, these systems that produce 2 sparks back to back are not that beneficial and only mask the real issue, 1 spark needs to do it every time!

Transistors/MOSFETs that could "handle" voltages exceeding 400 volts and ~10 amps of current flow were a long time coming. Prior to that, 1963ish, we had to use a 100 volt zener to limit the coil primary winding's inductive "kick" voltage rise and therefore a specialty coil with higher primary/secondary, 300:1, winding ratio.

Inductive energy storage, the Kettering system, was always been a better system for plug firing if one could remove the limitations of mechanical power switching. With the Kettering system spark energy is stored in the coil PRIOR prior to firing. Whereas with CDI it takes time, however brief, to transfer energy from the storage capacitor to the coil primary. With CDI the coil inductance resists the transfer of energy into the coil primary.

Once the solid state switching devices came along the "dwell" period could be raised as RPM rose, 99% even.

[mysocal911]

Originally Posted by scarceller

Here's my personal opinion about ignition:
You really only ever need just enough ignition energy to jump the spark gap. Often folks install way to strong ignition system for the needs of the engine. Not a good idea to over provision the ignition system as it causes a bunch of other issues.
If you are not doing a turbo setup then a simple basic ignition is all you need. Even the factory changed from CDI after the 3.0L. The 84-89 3.2L uses very basic 12vdc old school coil and it's good for 7000RPMs.
Not downing the after market CDI systems, I'm just pointing out that if the stock system can fire the plug and light the mixture you can't really improve things much. Furthermore, these systems that produce 2 sparks back to back are not that beneficial and only mask the real issue, 1 spark needs to do it every time!

Exactly!

[wwest]

Originally Posted by scarceller

Here's my personal opinion about ignition:
You really only ever need just enough ignition energy to jump the spark gap. Often folks install way to strong ignition system for the needs of the engine. Not a good idea to over provision the ignition system as it causes a bunch of other issues.
If you are not doing a turbo setup then a simple basic ignition is all you need. Even the factory changed from CDI after the 3.0L. The 84-89 3.2L uses very basic 12vdc old school coil and it's good for 7000RPMs.
Not downing the after market CDI systems, I'm just pointing out that if the stock system can fire the plug and light the mixture you can't really improve things much. Furthermore,

these systems that produce 2 sparks back to back are not that beneficial and only mask the real issue, 1 spark needs to do it every time!

Oh, really....?

Than maybe you can explain why the engine in my C210 sorta stumbles when I short out one of the magnetos for the twin plug air cooled engine. And why did Porsche supply a dual plug engine in some models?

[scarceller]

Originally Posted by wwest

Than maybe you can explain why the engine in my C210 sorta stumbles when I short out one of the magnetos for the twin plug air cooled engine. And why did Porsche supply a dual plug engine in some models?

When I say 2 sparks I don't mean dual plug, I mean firing one spark after another just in case the first one did not light the fuel. This is simply not very helpful since it masks some other issue with the ignition. Bottom line is that the first spark has to do the job and hoping a 2nd spark will help just hurts power and generates un-needed heat into the exhaust.

Dual plugs are used to help light the flame front from both side of a Hemi cylinder at the very SAME time. When using dual plugs vs single plug in a Hemi cyl it allows you to not need so much ign advance to generate peak torque conditions (max cyl pressure). The down side of the hemi single plug is that the plug is offset far to one side of the cyl and this results in needing a lot more ign advance than with dual plug. The more ign advance results in fighting the piston on the up stroke before TDC. It's the trade off needed to achieve max torque. This is why the very same exact engine build with dual plug vs single plug, the dual plug will generate more torque on the dyno.

[dicklague]

Originally Posted by scarceller

Here's my personal opinion about ignition:
You really only ever need just enough ignition energy to jump the spark gap. Often folks install way to strong ignition system for the needs of the engine. Not a good idea to over provision the ignition system as it causes a bunch of other issues.
If you are not doing a turbo setup then a simple basic ignition is all you need. Even the factory changed from CDI after the 3.0L. The 84-89 3.2L uses very basic 12vdc old school coil and it's good for 7000RPMs.
Not downing the after market CDI systems, I'm just pointing out that if the stock system can fire the plug and light the mixture you can't really improve things much. Furthermore, these systems that produce 2 sparks back to back are not that beneficial and only mask the real issue, 1 spark needs to do it every time!

I disagree with this position. The stock Bosch is a 45 or more year old design and a good modern ignition will make an early MFI or Carb car and even a CIS car run much better.

I have a 1973 2.7 with MFI. I drove it over 100,000 miles with points and stock CDI. I fine tuned the MFI very successfully in this time, but installing a good CDI system has made a HUGE DIFFERENCE in the way the engine runs, idles, revs and just plain has been a revelation.

Multi spark works. A hotter spark works.

You have to go into this with your eyes wide open. A more powerful CDI is not a plug and play deal. You need good ground, good +12 vdc power, good plug wires and a rotor and cap and wires that are up to the extra power.

I have bench tested the Bosch, MSD, and a Daytona-Sensors CD-1. The aftermarket units put out 3 to 4 times the power that the Bosch does.

If multi spark is so bad why do companies like BMW MB Porsche and others use it for starting and idling? Research it.

One weak spark is not good enough for most old P cars. My opinion with lots of research and practical experience.

Here is a link to my original post of my CDI experience Bosch 3 pin cdi replacement

[scarceller]

Originally Posted by dicklague

I disagree with this position. The stock Bosch is a 45 or more year old design and a good modern ignition will make an early MFI or Carb car and even a CIS car run much better.

I have a 1973 2.7 with MFI. I drove it over 100,000 miles with points and stock CDI. I fine tuned the MFI very successfully in this time, but installing a good CDI system has made a HUGE DIFFERENCE in the way the engine runs, idles, revs and just plain has been a revelation.

Multi spark works. A hotter spark works.

You have to go into this with your eyes wide open. A more powerful CDI is not a plug and play deal. You need good ground, good +12 vdc power, good plug wires and a rotor and cap and wires that are up to the extra power.

I have bench tested the Bosch, MSD, and a Daytona-Sensors CD-1. The aftermarket units put out 3 to 4 times the power that the Bosch does.

If multi spark is so bad why do companies like BMW MB Porsche and others use it for starting and idling? Research it.

One weak spark is not good enough for most old P cars. My opinion with lots of research and practical experience.

Here is a link to my original post of my CDI experience Bosch 3 pin cdi replacement

This simply means the old existing system was not doing the job and the new CDI is. But the bigger question is why was it not doing the job? Was it poorly designed or did it simply age? In your case you did the right thing to install modern CDI but I'm just making the point that if the ignition system is working properly then no point changing it. The down side to the older CDI systems was the points and having a CDI that's electronic trigger is more reliable but as is a electronic triggered inductive system as in the 3.2L.

Also for fuel ratios that tend to run on the rich side most of the time the high energy system tend to keep the plug a bit cleaner.

Just don't expect miracles to happen by installing a better ignition if the old one works. It's the same with multi electrode plugs (BOSCH 4 or 2) they really don't help if the standard style plug can do the job.

For engines with very high cyl pressures like Forced induction Turbo or high compression then I agree you need extra ignition to jump the spark gap (or close the gap down) as cyl pressures increase. But for most normally aspirated engines you don't need these high energy system.

BTW - love your car. Is that a high compression 2.7L?

[wwest]

Originally Posted by scarceller

When I say 2 sparks I don't mean dual plug, I mean firing one spark after another just in case the first one did not light the fuel. This is simply not very helpful since it masks some other issue with the ignition. Bottom line is that the first spark has to do the job and hoping a 2nd spark will help just hurts power and generates un-needed heat into the exhaust.

Dual plugs are used to help light the flame front from both side of a Hemi cylinder at the very SAME time. When using dual plugs vs single plug in a Hemi cyl it allows you to not need so much ign advance to generate peak torque conditions (max cyl pressure). The down side of the hemi single plug is that the plug is offset far to one side of the cyl and this results in needing a lot more ign advance than with dual plug. The more ign advance results in fighting the piston on the up stroke before TDC. It's the trade off needed to achieve max torque. This is why the very same exact engine build with dual plug vs single plug, the dual plug will generate more torque on the dyno.

And if the theory supporting single plug dual spark is correct then you also increase the flame front spread rate and thus get increased engine torque.

The question becomes....how fast is the "swirl" the A/F mixture is in just prior to the spark, and then how fast is the flame front from that spark advancing vs the "swirl" speed.

It should be pretty clear that if the second spark ignites an unignited portion of the mixture due to the "swirl" then a more rapid combustion of the overall cylinder "fill" will result.

[wwest]

Originally Posted by dicklague

I disagree with this position. The stock Bosch is a 45 or more year old design and a good modern ignition will make an early MFI or Carb car and even a CIS car run much better.

I have a 1973 2.7 with MFI. I drove it over 100,000 miles with points and stock CDI. I fine tuned the MFI very successfully in this time, but installing a good CDI system has made a HUGE DIFFERENCE in the way the engine runs, idles, revs and just plain has been a revelation.

Multi spark works. A hotter spark works.

You have to go into this with your eyes wide open. A more powerful CDI is not a plug and play deal. You need good ground, good +12 vdc power, good plug wires and a rotor and cap and wires that are up to the extra power.

Wires that are up to the....extra power....

Extra power....

1.) High enough voltage to reliability initiate a spark.

2.) enough current to sustain the spark

I have bench tested the Bosch, MSD, and a Daytona-Sensors CD-1. The aftermarket units put out 3 to 4 times the power that the Bosch does.

What have you found to be the differences amongst all those regarding spark sustainment time/period?

If multi spark is so bad why do companies like BMW MB Porsche and others use it for starting and idling? Research it.

No one has said multi-spark is BAD, just questioning its usefulness.

One weak spark is not good enough for most old P cars. My opinion with lots of research and practical experience.

Now that's showing a bit of unjust ARROGANCE! One person's opinion vs teams of highly educated, skilled engineers over the decades.

Here is a link to my original post of my CDI experience Bosch 3 pin cdi replacement

How long the spark plug "fire" is sustained is just as important, if not moreso, vs simply initiating the spark. Any modern day solid state Kettering distributorless system will outperform ANY CDI system you might bring to the table.

Upon firing the plug, how much, what %, of the previously stored energy is simply returned to the storage capacity?

[mysocal911]

Hopefully ignition system energy of the spark and voltage of the spark are not being confused.

The ignition system spark voltage determines maximum total gaps (plug & cap/rotor)
and cylinder pressures under which a spark can be produced. An ignition system producing
a minimum of 250/300 primary volts is more than adequate. The ignition system energy
is the energy available in the spark to fully ignite the fuel charge which is typically
30 milli-joules. Most OEM ignition systems produce 2-3 times this value.

[Robbbyg]

Please try this

1 check spark plug lead order
2 check sparkplug lead order again
3 Then check that your order is correct to the rotation of the rotor
4 if not reverse the order, A posche will still run if you have it reversed
3 check plug leads in dizzy are ALL the way in
4 check that the coil lead all way in

It could be as simple as that
Ive done that, then rechecked and rechecked again only to realise the numbers in my head were wrong.

[RussR]

did you change the coil from the Bosch CDI one to the Bosch Blue coil? or the MSD Blaster coil?

[Orange911S]

The ride home from work was up eventful. I had an even idle at stop lights and a smooth and quick run through the gears on the freeway. I run opposite the commute so getting above 70 mph was not a problem. The temp stayed normal which was not the case a couple of nights ago and the night before the backfire nightmare.

The new coil is an MSD blaster, recommended in Wayne's article #24. I copied the plug configuration from the cap I replaced. Since the car is a 77 but with just under 34,000 miles I don't think much has changed from the original.

For now I am going to sit tight on the ignition, but this conversation has me thinking about new plug wires and possibly going pointless.

I am learning a ton and thanks to all for the replies.