Ignition upgrades

[Quickstep192]

As I get my ‘73 Targa out of mothballs, I’m considering some upgrades in addition to just getting it running again. I get a fair amount of popping in the middle of the rpm range.

My car was originally a 2.4 with MFI.

The previous owner had it rebuilt to 2.7 and made the switch to Webers. He didn’t change the T cams and I’m pretty sure the distributor wasn’t re-curved. It has the original CDI

I’m considering switching to a 123 Distributor and maybe a classic retrofit CDI.


Any thoughts on that or alternative/better solutions?


I’d like to move away from working on the car and more into driving.

[kbken62]

Both are good choices. 123 with Bluetooth is nice for tuning


Sent from my iPhone using Tapatalk

[Schulisco]

Not to forget that the BT 123 incorporates anti theft function which can be managed by the smartphone...

I miss a vacuum port on the Classic Retrofit CDI+...or do I overseen it?

+1 for the 123...

Thomas

[rowingone]

I have a 72 2.4MFI and I went with the 123 distributor and bypassed the CDI. Runs great. You don't have to have a CDI with the 123 distributor so try just that upgrade first.

[Quickstep192]

It sounds like the 123 Distributor can be setup to use either CDI, or just a coil. Is one better than the other?

Performance is always welcome, but I’m mostly looking for drivability.

[rowingone]

you will get different opinions on which is better but for drivability and simplicity go without the CDI based on my experience.

[mysocal911]

Originally Posted by Quickstep192

It sounds like the 123 Distributor can be setup to use either CDI, or just a coil. Is one better than the other?
Performance is always welcome,

Not really! No spark energy increase is gained.

Originally Posted by Quickstep192

but I’m mostly looking for drivability.

Then just keep the original Bosch CDI without the 123.

[PeteKz]

If you go with the 123, buy their coil ($75) or use another coil that meets their specs (1-3 ohm primary resistance), and run straight from the dizzy to the coil. No CDI box needed. It is a simpler setup, with less to fail or go wrong.

The next step up is a coil-on-plug setup from Clewett, which also eliminates the distributor. Price in the $1700 range. You will need a PC or PC emulator to program it.

As Charles "Boss" Kettering used to say, "the part not added costs nothing, weighs nothing, and won't break."

[mysocal911]

Originally Posted by PeteKz

If you go with the 123, buy their coil ($75) or use another coil that meets their specs (1-3 ohm primary resistance), and run straight from the dizzy to the coil. No CDI box needed. It is a simpler setup, with less to fail or go wrong.

The next step up is a coil-on-plug setup from Clewett, which also eliminates the distributor. Price in the $1700 range. You will need a PC or PC emulator to program it.

As Charles "Boss" Kettering used to say, "the part not added costs nothing, weighs nothing, and won't break."

Right, but you lose your tach signal. Requiring a simple circuit, e.g. a couple resistors & a diode, to develop a low level (~ 7V) signal from the coil.

[HarryD]

There is a reason Porsche went to a CDI. The reason is that at higher rpms, a Kettering ignition has trouble building and collapsing it’s magnetic field fast enough to generate a decent spark. As a result, you get a high speed miss.

[Quickstep192]

Lots of great info here.

If my perception is correct that I could benefit from my distributor being re-curved, would I be better off to have my distributor re-curved or to get the 123?

[PeteKz]

Dave, With the 123-to-coil setup, the tach takes the signal off the negative side of the coil. Attach the black/purple wire there. It works.

Harry, the 123 uses a transistorized trigger, so the very limited dwell times of points type distributors does not strictly apply to the 123. Plus, it's programmable from your phone.

[mysocal911]

Originally Posted by HarryD

There is a reason Porsche went to a CDI. The reason is that at higher rpms, a Kettering ignition has trouble building and collapsing it’s magnetic field fast enough to generate a decent spark. As a result, you get a high speed miss.

Really? Why has Porsche since the 911 3.2, and all OEM ICE automotive manufacturers, use inductive discharge ignitions, i.e. NO CDIs?

That's the argument used in the '50s & '60s!

[mysocal911]

Originally Posted by PeteKz

Dave, With the 123-to-coil setup, the tach takes the signal off the negative side of the coil. Attach the black/purple wire there. It works.

Harry, the 123 uses a transistorized trigger, so the very limited dwell times of points type distributors does not strictly apply to the 123. Plus, it's programmable from your phone.

Did you forget about converting from the six pin CDI, which generates the tach signal?
Remember, the 911SC's tach would be damaged with a signal directly from the coil.

[HarryD]

Originally Posted by mysocal911

Really? Why has Porsche since the 911 3.2, and all OEM ICE automotive manufacturers, use inductive discharge ignitions, i.e. NO CDIs?

That's the argument used in the '50s & '60s!

Several reasons. The Kettering Ignition has, in relative terms a short, weak spark. CDI produces a short, strong spark. An Inductive spark produces a long, strong spark.

The reason for the ignition design evolution is to ensure the charge in the cylinder is fully burned at the correct time. At low RPM, Kettering is fine. CDI solved the problem of getting a strong spark at high RPM but did not help on the emissions front. Inductive ignition allows for a strong spark to ensure emission compliance.

Different courses for different horses.

[mysocal911]

Originally Posted by HarryD

Several reasons. The Kettering Ignition has, in relative terms a short, weak spark. CDI produces a short, strong spark. An Inductive spark produces a long, strong spark.

The reason for the ignition design evolution is to ensure the charge in the cylinder is fully burned at the correct time. At low RPM, Kettering is fine. CDI solved the problem of getting a strong spark at high RPM but did not help on the emissions front. Inductive ignition allows for a strong spark to ensure emission compliance.

Different courses for different horses.

Why are you even bringing this antiquated ignition system into the discussion?
It has no relevance in this thread. The last time a Porsche used it was in the late '60s.
Most all on the Pelican Forum know about "ignition design evolution".

[HarryD]

Originally Posted by mysocal911

Why are you even bringing this antiquated ignition system into the discussion?
It has no relevance in this thread. The last time a Porsche used it was in the late '60s.
Most all on the Pelican Forum know about "ignition design evolution".

Dave. Cool your jets. It is often important to understand how we got somewhere so we can move forward.

We are discussing why a 123 Distribuyor is an upgrade. I am just seeking to understand how it replaces the conventional distributor, points (or Pertronix) and a coil.

This article may help illuminate some of the details. https://gillsc.com/wp-content/uploads/2022/07/Ignition-Technology-Explained.pdf#:~:text=Capacitive%20discharge%20coi ls%20release%20almost,in%20a%20capacitive%20igniti on%20system.

As I stated earlier anything that gives a longer duration, high intensity spark is probably desirable. Hence the evolution from Kettering to CDI to modern inductive ignition systems.

[pmax]

The same exact discussion, participants and initiator included, from half a decade (!) ago ...

https://forums.pelicanparts.com/porsche-911-technical-forum/1027517-123ignition-distributor.html

What's the new news ?

[PeteKz]

Originally Posted by mysocal911

Did you forget about converting from the six pin CDI, which generates the tach signal?
Remember, the 911SC's tach would be damaged with a signal directly from the coil.

No, I did not forget. With the 123 dizzy direct to coil, there is no CDI box or 6-pin plug. The tach works fine with the tach signal wire connected to the negative (-) side of the coil. BTDT.

[H-viken]

Anyone try the twinplug distributor from 123?