Ignition upgrade advice - 1971 911T 2.2

[PNW Targa]

I've been scouring the forums for information on upgrades to the stock Bosch CDI ignition system on my 2.2L 911T. The car is running Webers in place of the original Zenith carburetors. It has SSI heat exchangers, but is otherwise mostly stock.

I'm looking at the ignition system both as an upgrade and with an eye toward getting the car to start a little easier. Cold starts take a number of crank attempts and judicious application of the throttle to get the engine to spin above 2000 rpms and begin to warm up. Occasionally I also have trouble starting it when warm, with a number of crank attempts required before the car fires up and idles beautifully. Yes there are plenty of places to make adjustments, but I'm beginning to think that upgrades to the ignition system could be a good place to start.

I'm currently considering two options. First, I've read a number of positive posts about Classic Retrofit's CDI+ system. I like the idea of using new components for the CDI box. I'm also intrigued by the ability to customize the timing curve. Cost here is an issue. The new CDI+ unit along with a new CDI-friendly coil (P***sKl****k) would be around $1500.

The other option would be a new 123ignition distributor. This would also allow for adjustments to the timing curve, but would leave the stock CDI unit in place. Since my original Bosch distributor is likely due for a rebuild ($300), this would save that potential expense (which I may need if I were to go with the CDI+ unit). I also like the Bluetooth PIN option for adding a layer of theft protection. If I were to also put in a new coil along with the 123 dizzy, the cost here would be about half as much as the first option, at around $750.

With either option, I'm also looking at replacing the points with a Pertronix system. At first this seemed to be a no-brainer based on comments, but I've been running across a few posts that question the consistency of the pointless system across all cylinders. Since I don't mind checking dwell and new points are cheap, I may hold off on going pointless. I think I'll at least try out the new CDI+ unit or new 123 distributor and go from there.

What do you all think? The targa runs great once it's going. I'd really like to get it to start more easily and more reliably. I like the idea of playing with the timing curve to see what I can do with responsiveness at different RPMs. With either option I think I'll see improvements.

- Rich

[RSTarga]

Stick with the factory CDI, get a High torque starter. You need to pump the webers a couple of times on cold starts. I don't think they have a choke.
Check float levels.

[gamin]

Use of the hand throttle helps with cold starts. Partially open the hand throttle, pat the gas a few times, then start. Close the hand throttle as the engine warms up. With no choke the hand throttle is your friend.

[digitaldgp]

I went with a 123 B/T in my 1970 911T 2.2, and had Bob Ashlock up grade my CDI. Car runs great!! And I used my hand throttle when warming up.

[coldstart]

1972 911: I use a Bosch high torque starter, Petronix ignition (instead of points) and an MSD box and coil. All replaced about 7-8 years ago.

The box makes a huge difference in power as my CDI box was weak. The new starter (6-8 years ago) makes starting much easier. Highly recommend the upgrade. Keep all the old parts.

[47silver]

Pertronix and msd car has mfi starts easily

[mysocal911]

Originally Posted by digitaldgp

I went with a 123 B/T in my 1970 911T 2.2, and had Bob Ashlock up grade my CDI. Car runs great!! And I used my hand throttle when warming up.

What does that (upgrade) mean exactly, i.e. Did Bosch poorly design the CDI or use marginal parts?
The Bosch CDI, both the 3 pin & 6 pin, are very reliable based on studies over the last 40 years.

[47silver]

I was having issues with my mfi and was trying everything so installed an msd. It was tge pump needed rebuilt. I am Toolazy to put the cdi back in but will as the msd eats rotors and coil wires

[Hi_Fi_Guy]

The original CDI was cutting edge when new and even today continues to be a mostly maintenance free system. That said advances have been made over the past 50 years and newer systems have the potential to offer improvements from idle to redline while removing additional points of wear and failure.

Vendors offer options for the ignition trigger (distributor/crank position sensor), CDI, coil, ignition wires and spark plugs. Changes to the ignition system have the potential to improve engine smoothness and responsiveness, at idle, midrange, and top end. Porsche’s stock system is better than most but does leave room for those who want to take advantage of modern tech to enhance reliability and performance.

[mysocal911]

Originally Posted by Hi_Fi_Guy

The original CDI was cutting edge when new and even today continues to be a mostly maintenance free system. That said advances have been made over the past 50 years and newer systems have the potential to offer improvements from idle to redline while removing additional points of wear and failure.

Vendors offer options for the ignition trigger (distributor/crank position sensor), CDI, coil, ignition wires and spark plugs.

These are external to the CDI design!

Originally Posted by Hi_Fi_Guy

Changes to the ignition system have the potential to improve engine smoothness and responsiveness, at idle, midrange, and top end. Porsche’s stock system is better than most but does leave room for those who want to take advantage of modern tech to enhance reliability and performance.

These came from the modern day inductive discharge ignitions, not CDIs, used on ALL present day ICEVs.

[Funcity]

I swapped my CDI box out for the CDI+ on my Webber swapped 76 911s. It’s been great. Just got it back from the shop with an overlay map. I would recommend!
Cheers

[Hi_Fi_Guy]

@mysocal911, do you have any advice for the original poster or are you just here to crap on those trying to contribute to this forum by sharing their knowledge and experience?

Perhaps you believe there is no solution better than the original CDI. That’s fair enough, be direct and say so in a response to the original post. No need for the passive aggressive replies to other members’ responses.

[buster73]

I opted for a 123 ignition distributor (USB version) with stock Bosch CDI unit and coil. Very happy with the result:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/1139902-weber-carburetor-ignition-tuning-modified-3-0-a.html

[PNW Targa]

I'm not seeing much in the way of support for the CDI+ box. More posts here favoring a new 123ignition distributor. That option would give me a new distributor and coil. I could then look into a rebuild of my CDI box, rather than going with the additional upgrades in the CDI+ unit.

I appreciate the suggestion for a high-torque starter. I find that the starter cranks the engine fine, but didn't know there were high-torque options available. I suppose if the high-torque starter gets the engine up to higher RPMs, it's more likely to fire up successfully. I'll look into this.

[Black 993]

You might want to adjust your starting procedure. On my '70T, I get great results with the following: if I haven't run the car in a few days or weeks, turn the key to the 'on' position and wait about five seconds so fuel pressure builds and float bowls are full. Give the gas pedal a couple of pumps. Then wait a few seconds (you want fuel vapor in the intake), then start it with your foot pressing the gas pedal down around halfway. On my car, it fires up almost instantly. As for cold idle, it's never going to take care of itself. You can either use the hand throttle or just don't let it die for the first minute until it's warm enough. My car idles fine after about a minute.

Something I didn't realize before I got a carbureted 911 is that fuel evaporates from the float bowls pretty quickly. On my car, if it's been sitting for a few weeks, the bowls are basically empty. You have to let the fuel pump refill the bowls, and I find it helps to do this even if it's been sitting a few days. FWIW, I'm running stock ignition and points and it starts perfectly every time....if I do the above procedure.

As for hot starts, those are harder. I give it a couple of pumps and then hold the gas down halfway and crank. I have not found a way to start it without 2-3 seconds of cranking. If anyone has any suggestions, I'm all ears.

[PNW Targa]

That sounds pretty close to my cold start procedure. Turn the key to 'on' and let the fuel pump go to work for a bit. Pump the throttle a few times. Turn the key fully and use a combination of foot pedal pumps and hand throttle to try to get it going. The challenge is that it often fires up to under 1000-1500 RPMs for a second, then dies. After a number of attempts I can usually get it past 2000 RPMs, where it will roar to life. I'll use the hand throttle at that point to keep it at 2000-2500 until it's warm.

A failed warm start is really different. The car will crank, but not fire. It can take 6-10 crank attempts to get it to go. Once it does fire up, it goes right into a nice idle. There's none of the partial running and dying that happens at cold start. And of course much of the time it fires right up during a warm start.

At first I thought I might be dealing with poor fuel delivery or carburetor settings. However I've been reading about the role that the distributor can play at start. That got me thinking about upgrades to the ignition system.

On a side note, I'm really glad I replaced the plastic lever that is attached to the hand throttle. When I got the car, the hand throttle did nothing. This was due to the plastic control arm underneath being completely decomposed and lying in bits in the tunnel. Having a working hand throttle is so nice.

[Black 993]

Have you checked your plugs and plug gaps?

[mysocal911]

Originally Posted by buster73

I opted for a 123 ignition distributor (USB version) with stock Bosch CDI unit and coil. Very happy with the result:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/1139902-weber-carburetor-ignition-tuning-modified-3-0-a.html

Better yet, the 123 system driving an inductive discharge coil, e.g. modern Porsche (911 3.2 thru 993), and simple & reliable.

[PNW Targa]

I'm working my way through the plugs, points, timing and dwell. Plugs have a lot of carbon fouling. Not sure how much is due to modern fuel (though I have access to ethanol-free premium) or a too-rich mixture. Will replace and monitor. Next up is to check the timing and dwell. Working on finding a 13mm wrench for the distributor that's functional, given the limited clearance.

[Schulisco]

Originally Posted by PNW Targa

I'm working my way through the plugs, points, timing and dwell. Plugs have a lot of carbon fouling. Not sure how much is due to modern fuel (though I have access to ethanol-free premium) or a too-rich mixture. Will replace and monitor. Next up is to check the timing and dwell. Working on finding a 13mm wrench for the distributor that's functional, given the limited clearance.

First and foremost from my point of view - the mixture is the main reason for carbons at the spark plugs after the wrong heat range of the plugs. So make sure that you're using the specified spark plugs for the engine. But also how you're driving the car. Cruising for ages at low speeds and rpms causes that plugs won't reach their self cleaning temperatures.

https://www.championautoparts.com/Parts-Matter/automotive-repair-and-maintenance/how-to-read-spark-plugs.html
https://ngksparkplugs.com/en/resources/read-spark-plug
https://am.denso.com/plug-global/basic/select/
https://www.denso.com/global/en/products-and-services/automotive-service-parts-and-accessories/plug/basic/heatrange/

Sooted plugs were one of the reasons why Porsche introduced the CDI ignition system because it generates way more ignition power to break soot to ensure a proper combustion under any conditions. Carreras with a much more precise mixture control run leaner than CIS and carbureted cars. So they run fine with transistorized igntion systems.

Todays 123igniton can create almost the same ignition power as the CDI, especially with a igniton booster like the "BigFatSpark" module which is basically nothing else as a common ignition amplifier module from the 90ies. 123ignition also provides high power ignition coils, so they can waive a amplifier module.

Concerning your interest in upgrading your ignition to a 123ignition I suppose to think about this variant: Afaik the CDI on the early 911 - as yours too - the CDI is triggered with breaker points. 123 dizzys are basically nothing else as a transistorized ignition mimicking breaker points. (Only SCs used magnetic pickups in their dizzys whose also required other CDI boxes to manage that signal.)
So you can still use the CDI box from your car, but replacing the dizzy with the 123. Instead of connecting the coil direct to the trigger output of the 123, you can use the signal to manage the CDI box, so that the coil is connected to the CDI box again as the original setup...with this approach you have the best of both worlds: Still CDI, but a modern microprocessor controlled and programmable ignition timing with a new dizzy...
I successfully tested this variant lastly on the workbench with a Permatune CDI GS (general service) box which was intended to be used on cars other than 911. But still 911 box should the job as well if it can use breaker signals...
Keep in mind - this approach won't work with SC dizzys!

Thomas