6 Volt CDI units?

356 Porsche-related discussions and questions.
Message
Author
User avatar
Jack Walter
356 Fan
Posts: 403
Joined: Fri May 09, 2008 9:36 pm

6 Volt CDI units?

#1 Post by Jack Walter »

I'm trying to get a more reliable spark in my 6 Volt 4-cam Carrera engine - as we know the hemispherical combustion chambers with twin plugs are a little prone to fouling plugs and rough running if both plugs don't fire at exactly the same instant. After some testing on a distributor machine we found that one of the two distributors was lagging about 200 RPM behind the other one on the advance curve so we have been able to adjust the errant distributor to closely match the "good" one that matched up pretty well with the factory advance curves. But I think there is still some improvement to be made.

I was talking to some of the guys at Amelia that run the 550 and RSK Spyders and the best suggestion they had was to fire both coils off one trigger - either one set of points or a crank fired sensor.
This would definitely eliminate the variation you see in timing between the left and right distributors when running conventional points in each distributor. Most of these guys are running 12V CDI units but I don't want to go through the trouble of converting the car to 12V and have been looking at a 6 volt solution.

I think I've found a good solution with a real old time CDI unit - manufactured by the son of one of the pioneers in the CDI world. http://www.capacitordischargeignition.com/

http://mgaguru.com/mgtech/ignition/ig207w.htm

I've been corresponding with Fred Winterburn over the past couple of months and he's been playing around with different configurations of wiring layouts and a couple of his 6 Volt CDI units (yes he still makes 6 Volt CDI's) and we think that I can use one distributor with a pair of his CDI's to trigger both coils and get a good hot spark at both plugs at the same exact moment.

Here's a video showing the spark intensity with the Winterburn CDI

https://www.youtube.com/watch?v=lsxzDPLaXtA

So what do you guys think?

User avatar
David Jones
Classifieds Moderator
Posts: 7323
Joined: Tue Mar 25, 2008 6:32 pm
Tag: I wish I knew as much as I think I know.
Location: Kentucky

Re: 6 Volt CDI units?

#2 Post by David Jones »

Jack, I have 6 volt Permatune units on all my cars and so far over 15 years no failures. Points only wear out because of wear on the rubbing block so have to be adjusted periodically. They will throw a spark across a 43 thou spark plug gap even using a 9 volt dry battery. I am talking about the type of battery in a smoke detector. They cost more than the Winterburn unit and about the only way to get one is used as I do not believe Permatune make the 6 volt unit any more and if you find one as I say they are going for more than the Winterburn unit.
I am certain from my own experience with ignition systems that your idea will work as the current and voltage that passes through the points is so low there will still be negligible load on the points.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
David Jones #9715

User avatar
Jack Walter
356 Fan
Posts: 403
Joined: Fri May 09, 2008 9:36 pm

Re: 6 Volt CDI units?

#3 Post by Jack Walter »

Thanks - that is good to know. It sounds like we are definitely on the right track and your experience reinforces our ideas.

Fred is a nuclear engineer whose hobby is to refine and improve on his father's original design using more modern and robust components.
We've emailed back and forth a couple of dozen times and I'm feeling very confident that my ignition problems will soon be a thing of the past.

Now if I just get over my dislocated left elbow quickly so I can use my arm again...ladders are evil and gravity always wins.
Attachments
elbow view1VIEW0001.jpg

User avatar
David Jones
Classifieds Moderator
Posts: 7323
Joined: Tue Mar 25, 2008 6:32 pm
Tag: I wish I knew as much as I think I know.
Location: Kentucky

Re: 6 Volt CDI units?

#4 Post by David Jones »

Jack, if ever I will be able to breath again without oxygen I will be a happy man. I would trade two broken arms just to be able to climb a ladder. Right now I am waiting for my wife to relent and believe I can drive a 356 or the boxster while carrying a small oxygen cylinder.
I read Winterburn's web page and I would say that is the solution to go for just as good as a Permatune would be. Do not know where you are but if you post your location and ask there may be someone around who would loan you a pair of CDI units to test out your idea. I only have one extra and I am sure you are nowhere near Kentucky.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
David Jones #9715

User avatar
Jack Walter
356 Fan
Posts: 403
Joined: Fri May 09, 2008 9:36 pm

Re: 6 Volt CDI units?

#5 Post by Jack Walter »

Thanks for the offer but I've gone ahead and ordered a pair of the Winterburn CDI's - he's giving me a slight discount for ordering two. I should have them in about a week and a half since they have to come from Canada and it may be a while longer until I'm nimble enough to install them but I'm pretty confident that this will work for me. 911's have the same plug fouling issue with the same basic combustion chamber shape so its not like I'm experiencing something new here.

I'm pretty lucky - could have been hurt a lot worse even though I only fell about two feet - just stuck my arm out to keep from going face first into the ground (been there - done that). I'm sorry to hear about your health issues and hope you figure out a way to strap that oxygen cylinder to the back of your seat and go for a nice drive.

User avatar
Bill Sargent
356 Fan
Posts: 1142
Joined: Thu Apr 10, 2008 11:03 am
Tag: Faux-Cam
Location: Seattle, Washington

Re: 6 Volt CDI units?

#6 Post by Bill Sargent »

Jack,

I would be interested to hear how your test goes. If you still have problems the guys at Speedco BV have reproduced the 4 cam distributors and can supply them with a 123 Pointless ignition. The guts are in only one distributor with the other used as a slave and they have a CD box with the system. I purchased a set of the distributors for a motor project with this set up. You can program the advance curve from your iPhone with the motor running. They are 12V but I think they also do a 6V set up. They could probably assist with fitting such a set up to your distributors.

I have had similar plug fouling issues in my 2 liter motor. Running at over 5000 rpm for a few minutes usually clears the plugs, but is a pain. Part of my problem is a set of 48 IDA Webers that came with the motor - it was used in a 904 for vintage racing and it runs well above 5000 rpm but has a big flat spot about 3500. I have a set of Solex 44 carbs that 356 Carb Rescue built for me using a set of split shaft Solexes converted to solid shaft and bored to 44mm. I hope to install them before the Emory Campout and will let you know if that helps with the stock ignition using pertronix modules (my current set up).

I am still living in China so will not have enough time on the trip back for the campout to install the Speedco distributors. I need to retire so I have more time to play with this stuff.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

Olivier Auvray
356 Fan
Posts: 326
Joined: Thu Apr 10, 2008 2:19 pm
Location: Porscheville France
Contact:

Re: 6 Volt CDI units?

#7 Post by Olivier Auvray »

I use very small "ignition box"....... not CDI but works well:
$(KGrHqNHJEwFHitH,!GYBR+mZL2LRw~~60_1.jpg
This one is for a 3 cylinders with 3 coils and 3 points sets (DKW).

The guy who did them is out of business....... but I think you can find the same stuff in USA (from another company).

It's cheap, small & reliable!

On Carrera, as you told, I use one box, one set of points on the best distributor, and 2 coils. The second distributor is only a spark distributor!

User avatar
Jeff Adams
356 Fan
Posts: 148
Joined: Wed Jan 21, 2009 9:54 pm
Location: Connecticut
Contact:

Re: 6 Volt CDI units?

#8 Post by Jeff Adams »

Jack - good find on the Winterburn units. Last 6V car I did for a Carrera Speedster customer, I found a set of NOS Delta Mark 10 units and they worked fine. Does anyone know if Permatune is still in business? I had a 6V Permatune unit on my daily driver pushrod 64C back in the day, and occasionally had a problem with no spark during cranking, as the voltage could drop enough to keep the unit from firing.

For either 6V or 12V Carreras, one advantage of the CDI units is being able to use the points signal from just one distributor to fire both banks of spark plugs. You can't do this with the stock points/coil system. You can rebuild the two distributors and try to make the advance curves the same, but there will always be some small deviation during actual running conditions. I have been using the MSD Street Fire units on 12V cars, and they work pretty well.

Bill - does your 2 liter engine have high lift cams to go with the 48IDA Webers? If it is a 587/1 engine with standard single dot 10mm lift cam lobes, then the 48mm Webers are a major mis-match. Same with the 44mm Solexes. Keep in mind that if you switch to the 44 Solexes, you will need different intake manifolds. No matter what combo you have, the CDI units will help your engine run better.

User avatar
Bill Sargent
356 Fan
Posts: 1142
Joined: Thu Apr 10, 2008 11:03 am
Tag: Faux-Cam
Location: Seattle, Washington

Re: 6 Volt CDI units?

#9 Post by Bill Sargent »

Hi Jeff,

My motor is a 587/1 rebuilt by Stanley Gold's mechanic and Jacques Le Friant for vintage race use with dot 2 intake cams, dot 1 exhaust cams and 904 P&C. Motor runs well when plugs are not fouled and Dynoed at 139 Hp at rear wheels which seems about right for what is effectively a 904 street spec motor. The off idle transition issue and flat spot at ~ 3500 rpm are the main issues, besides the plug fouling, that lead me to make a carb change for street usage. Hopefully the 44 Solexes jetted to 904 street specs will help. I have a set of the Solex Manifolds, throttle linkage cross bar and mount brackets.

I also have a set of Weber 46 IDM carbs currently being rebuilt at Pierce Manifolds. Do you know if they will fit on the same intake Manifolds as the 48 IDAs? I have a set of Manifolds that came with the carbs, but if they fit the 48 Manifolds that would be helpful.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

User avatar
Jacques Lefriant
356 Fan
Posts: 4601
Joined: Mon Dec 06, 2010 1:50 pm
Location: Washoe county NV

Re: 6 Volt CDI units?

#10 Post by Jacques Lefriant »

Hi Bill, Jeff and Jack
I developed a crank fire system for the 4-Cam back in 1992 it works exceptionally well with cam mounted distributors and we can incorporate it to function like the dummy units on a DME like the 911 3.2/3.6 dual. I can provide analog or digital advance curves you can also incorporate vacuum adv and turbo/supercharger functions. I am considering making a 6V version for a customer. BTW i currently have a highly modified 587 engine on my test stand and i had to incorporate the Crank fire unit to get it to run it is producing more power than any 904 engine i have seen. i had to use it since no stock system would function. Bill a good idea with the 123 dizzys but Jack needs CCW ones like for a Volvo.
j
 

User avatar
Jack Walter
356 Fan
Posts: 403
Joined: Fri May 09, 2008 9:36 pm

Re: 6 Volt CDI units?

#11 Post by Jack Walter »

I'm going to use the CCW distributors I got from Rainer but only use the points in one of them to fire both coils. Fred has experimented with this setup and has sent me a wiring diagram with how to hook everything up correctly. He also says he has successfully fired a hot spark with only 3V so apparently his unit is a little more forgiving than the Permatune. One of you other guys just snagged the last 6V unit he had built (after he shipped my two) and he says it may be a while before he gets a chance to build some more. His real job is running a nuclear reactor and he just builds CDI units in small batches in his spare time. So I'll keep everyone informed as to how all of this works and by the time I get everything hooked up and checked out maybe he'll have some more ready. He really appreciates the interest in his fathers work and says thanks to the 356 guys who have contacted him as a result of my post.

User avatar
Geordie Greenwood
356 Fan
Posts: 41
Joined: Sat Nov 29, 2008 1:52 pm
Location: Surrey BC Canada

Re: 6 Volt CDI units?

#12 Post by Geordie Greenwood »

I recently purchased and installed a 6 volt Winterburn CDI in my '59 356A. Fred was a pleasure to work with and offered some great advice as well as designing a trigger unit for the SC electronic tach I use. I would recommend this product for any performance application. No affiliation, just a happy customer.

Geordie
Attachments
IMG_0614.JPG
Geordie Greenwood
Surrey BC

Lars Hvidsteen
356 Fan
Posts: 95
Joined: Sun Jul 30, 2017 4:33 pm

Re: 6 Volt CDI units?

#13 Post by Lars Hvidsteen »

can the 6 volt Winterburn CDI be used together with a 123ignition / distributor?
Porsche 356 B T6 1962/7 Slategrey/Coralred
Porsche 911 1966 Bahamayellow/Black pipita

User avatar
Geordie Greenwood
356 Fan
Posts: 41
Joined: Sat Nov 29, 2008 1:52 pm
Location: Surrey BC Canada

Re: 6 Volt CDI units?

#14 Post by Geordie Greenwood »

Lars you would have to check with Fred to see if they are compatible
winterburnignition@gmail.com

Geordie
Geordie Greenwood
Surrey BC

Lars Hvidsteen
356 Fan
Posts: 95
Joined: Sun Jul 30, 2017 4:33 pm

Re: 6 Volt CDI units?

#15 Post by Lars Hvidsteen »

Thanks Geordie

Is it just plug and play,? or do you need new coil , distributor , bigger sparkplug gap, Carburator/ignition settings?

Lars
Porsche 356 B T6 1962/7 Slategrey/Coralred
Porsche 911 1966 Bahamayellow/Black pipita

Post Reply