Correct and/or Best ignition for 68 911S

[LDunville]

I'm in the process of a total restoration of my 1968 911S Targa SWT. This was a Euro car, being that no Esse's were delivered to the US, for pollution reasons. My intent is to do the best resto possible, but still periodically drive the car. This will not be a garage queen or purest show car, but I'm still trying to get everything correct down to having the hose clamps Cadmium plated.

I'm trying to go 100% original, but I'm about to make my only concession to originality. It's my intent to replace the points with a Pertronix and the 6 pin Permatune with a modern MSD ignition. My thought is that this will make for a much more reliable driver and can be retro fitted back easily, if for some reason I or a future owner wants it to be original.

I'm about to install the newly rebuilt engine and just got the March 2014 Esses magazine in which PartsKlassik is advertising a "completely new digital CDI Ignition system". Now I'm in a quandary. Is this a better option to the original Permatune? It's a very expensive option at almost $1000 with the required original coil.

It seems I have three options;
1. Refurbished Permatune
2. MSD/Pertronics
3. Partsklassik CDI system (at about 2 to 3 times the cost of #1 or #2)

Bottom line it's worth it to me to get it right, but I'm not sure what right is. According to the article on page 20, Porsche didn't introduce the CDI until 1969 so maybe I should not even consider the CDI in the first place???

I look forward to any informed opinions on the topic.

Thanks in advance
Larry

[Jim Breazeale]

Your car came originally with a conventional distributor with old reliable points and a 12 coil and condensor. Those work just fine. You state that you want the car "original". Why not just leave well enough alone have a perfectly reliable ignition system? I must admit to being a Pertronics and Permatune hater, though.

Regards

Jim

[gsjohnson]

Jim-CD units in general will help with starting and low RPM drivability up to 3500 RPMs. I run an MSD on my 68 911 and I love it, but I built my car to drive. I still retained the original points as the trigger. I also painted my MSD unit black so it wasn't such an eye sore in the engine bay. That red is pretty loud.

[Jim Breazeale]

Jim-CD units in general will help with starting and low RPM drivability up to 3500 RPMs. I run an MSD on my 68 911 and I love it, but I built my car to drive. I still retained the original points as the trigger. I also painted my MSD unit black so it wasn't such an eye sore in the engine bay. That red is pretty loud.

Gary and Larry

No argument there. I am just saying that a coil, conventional points, condenser, set up is very reliable and works flawlessly in millions of cars.
By the way, Mishawaka, Indiana happens to be the home town of a pretty knowledgeable Long hood Porsche guy. I hope you are using Jim S. as an adviser and listening to his sage advice.

Regards

Jim B

[NorthernThrux]

I'd keep it original too. Other than some additional infrequent PM work, it is perfectly reliable as Jim B said. You are not changing your engine into a high performance monster that might benefit from these editions, so why not get the whole OEM effect ?
Ravi

[304065]

I have used them all over the years-- Bosch CDI, MSD 6AL, Bosch Inductive, Alison/Crane etc.

"Reliability" means different things. To me it means long service life with the ability to immediately diagnose and repair in the field inexpensively.

I agree with Jim (not on purpose) that the most reliable solution is a set of good old Bosch points, with a spare set carried in the glove compartment. For long trips you are probably carrying a multimeter so it's easy to set the dwell and static timing and be back on the road if they fail.

You cannot reliably diagnose a bricked pertronix or optical trigger at roadside.

Points bounce at high RPM, but if you are flogging your 68S that hard you need a different solution entirely. For street use they are just fine.

The limitation of points is that you can only put four or five amps across them before they burn up. So the coils used with points have both a high primary resistance (on the order of three ohms total including ballast resistor) and a high inductance in order to store magnetic energy in the coil. The combination of lower amperage and higher inductance means that the coil doesn't have time to fully charge at high RPM. Hence, the Bosch CDI in 1969. But CDI has a limitation in terms of spark duration, so the Factory went back to Inductive ignition in 1984 with the Motronic system. Modern transistors allow a low-resistance coil to charge quickly enough to deliver sufficient ignition energy with a fat spark and low cost.

So much for the history of Porsche ignitions. Anyway, you have a couple obvious choices:

1) Bosch CDI. This will sorta fit on the electrical console if you move things around.
2) MSD. Cheap, short-duration spark CDI system, available everywhere
3) Kettering-ignition. Of course this is the original system. Fouls the plugs below 4000 rpm, hard starting when cold even with Ballast resistor.

Despite the originality of Kettering, I don't recommend it for anything except getting to the Concours field and back. Bosch CDI is the kind of thing you could leave installed, and I don't think you would get a hard time for using a factory part that appeared a few months after your car was born. MSD is probably the cheapest but is clearly modern, which is why folks conceal them behind the air cleaner.

You could use the pertronix igniter, it's a solid-state switch with a capacity of about seven amps, which when used with one of their low-resistance coils will generate a lot of inductive ignition energy. Of course it also contains a hall-effect ignition switch. If it breaks you're in trouble because you can't see what's broken, and you can't switch to points with the low resistance coil because you will burn it up.

Hope this helps

See here for more

http://forums.pelicanparts.com/porsc...electrics.html

And see here for graph of the time-to-charge for various coils

http://forums.pelicanparts.com/porsc...discharge.html

[Fritz A. Ficke]

The carbed early 67 then 68S was notorious for fouling spark plugs with the stock ignition. Also cold drivability was bad since there was no enriching device on the IDA or the later IDS carbs used on the S. These cars benefit greatly in drivability with some sort capacity discharge ignition system that boost the spark voltage up and will ignite these lean mixtures during warm up, the MSD, being the cheapest and as reliable as the Bosch I would suggest going with that, painted black as suggested earlier.
Another benefit of MSD/Bosch capacity discharge system is the low voltage over the points makes for long point life since only the wear block rubbing is the only worry for the points going out of adjustment.

[66S]

Porsche recommended either the Delta Mark 10 or Sydmur Fireball CD ignition as a retrofit for early 911s. The Sydmur unit is pretty hard to find, the Delta is really easy to find and inexpensive so you can have a spare if you want. The Delta also has a switch to go back to conventional ignition. my 66 has a Delta already installed and my 67S will have one also. Radio Shack sold Delta units as do it yourself kits wayback. All 911 motors need a CD ignition in my opinion. they just run better. I dont like MSD, they are not as reliable as Bosch. that is why Nascar teams have two MSD setups with a switch. Maybe its those cheap Chinese electrolytic capacitors opposed to polyester capacitors used by Bosch. Ive seen pallets of bad MSD boxes on ebay.

[Schiefer]

Hi Larry,
I´m looking into the same things at the moment. More info to come in this thread about the digital CDI ignition system:
http://www.early911sregistry.org/for...m-PartsKlassik

MSD & Permatune is too "modern" for me.

I have been considering Pertronix for a couple years but have not been able to make up my mind. Now I have decided to stay with points because of the kind of advice "304065" is giving above. I need something that is rock solid, but also possible to fix when you are on the road. Yes, I could bring a a second pertronix, but am confidant now CDI and points will work fine for me.

This is also supported by Kurt at Partsklassik:
As for the pertronix system, that is a personal choice. My response to it is when using a CDI ignition system the load across the points in very light which results in minimal points wear. This means that the points will tend to last for a very long time. Using the Pertonix system will not give you any preformance gains and the distributor stills needs to have basic maintenance which will still require you to remove the cap and rotor to lube the Points cam. To sum it up I can buy a lot of points sets for the cost of a pertronix unit and In my own personal cars I use the points.

I think Sydmur/Delta is very cool period piece that I would love to have in my car, but I cant take any chances with reliability. These boxes are also getting old. I have even checked if it is possible to fit the modern electronics in Kurt´s boxes into a Sydmur, but not possible.



Radmund

[dicklague]

I have Pertronix in my 73 911 MFI 2.7 and love it. I carry a spare set of points and even a spare Pertronix and hav never needed them in 9 years.

About a year ago I started researching if there was anything better than the Bosch CDI for early 911s. I looked at MSD, Crane, and others. After much research, I finally decided to install a Daytona-Sensors CD-1 ignition and coil. http://www.daytona-sensors.com/CD1.html .

I am very satisfied with this unit. The quality build is way beyond anything that I have seen. Very modern mil-spec surface mount board with very high quality components. It is full of features and can even data log what is going on in your ignition, and control the timing if you have a crank fire trigger. And Made in the USA.

It works great with my Pertronix Hall effect ignition. I am recording RPM, MAP, and timing. The rev limiter is adjustable from the outside and it is a nice soft limiter not the 'hit the wall' that you get with the rotor mechanical limiter.

My MFI is quite well tuned, but the car starts better, revs better, and idles much better with the CD-1. It is not cheap, but a very good value considering the performance and the fact that it comes with a matching high quality coil.

I highly recommend it for an earl 911. It is a very solid product.