Twin Spark Firing using single CDI Box

[KNIGHTRACE]

I am speechless.... WTF. good Henry covered reverse polarity.. Maybe this is humor and I totally missed it.

[dannobee]

The blue vs green was explained to me at one of the factory training classes. If you look at the voltage spikes with an oscilloscope, the "correct" way will have an upward initial spike, then a downward negative spike. Somewhere in the middle is where the falling edge triggers the spark. If you reverse rotation, the first spike is the downward negative spike, then the upward positive spike, THEN the spark is triggered. But since this line occurs over more time, the spark trigger is inconsistent, explaining the 30-60 degree timing difference.

The explanation to us was that because the distributor rotation is backward, the magnet polarity is backward, although I've never independently confirmed that. The big takeaway from the lesson was, "don't substitute the green one for the blue one."

[winders]

Originally Posted by LJ851

Winders, would you be OK if someone used a MSD ignition differently than you did on your engine?

Anyone can use MSD ignitions anyway they want. But even MSD will tell you the best way to use their 6AL ignitions on a twin plug setup is to use two coils and two ignition boxes.

[KNIGHTRACE]

I have a Fluke 99b scope meter if anyone would like to purchase it, I do not hardly use it anymore.

[Henry Schmidt]

Originally Posted by dannobee

...edit... The big takeaway from the lesson was, "don't substitute the green one for the blue one."

The big takeaway should be, "verify the A vs B connection before using". Because the blue wire hasn't been available for 30 years.

[LJ851]

Originally Posted by KNIGHTRACE

I am speechless.... WTF. good Henry covered reverse polarity.. Maybe this is humor and I totally missed it.

Was this directed at me ? What did I do wrong ?

[dannobee]

Originally Posted by Henry Schmidt

The big takeaway should be, "verify the A vs B connection before using". Because the blue wire hasn't been available for 30 years.

That was about when I took that class, before the blue was discontinued.

But yes, swap the terminals.

[KNIGHTRACE]

LJ851, wasn't trying to be rude. I felt I explained clearly in this post how individuals could and should check their polarity when installing a new MSD. This has been the hardest thread I have ever been a part of. Henry above encourages people who have to resort to using an MSD use the 6Al analog unit rather than the 6Al digital. I called summit racing and they no longer make the non digital version. So if it is better it does not actually matter since it is not produced anymore to the best of my knowledge. I figure you did not see my post above trying to help people to check their polarity without having a $4000 scope meter. And the blue green wire thing is cool trivia but it still does not tell people what their polarity is on their distributer. I know the 76,77 Carrera and turbos used a 2.7 clockwise rotation distributer but the majority are counter clockwise. I have been sick the past week or two and they gave me a Z pack that has helped my health but hard on my disposition so I give you my word I am trying to be respectful to everyone. You stated in your post " Winders would you be ok if someone used a different MSD than you did ?" I am sure he did not understand that as we did not use a distributer or MSD's. I bring up the question because I feel you may have been asking a question that we did not understand and it was not some kind of humor. If it was Im sorry I missed it. Please accept my apology if this came across wrong. Maybe I was too serious just trying to provide help to the community and I sincerely meant no disrespect to you or anyone else.

[Henry Schmidt]

Originally Posted by dannobee

That was about when I took that class, before the blue was discontinued.

But yes, swap the terminals.

Got it. I just didn't want anyone wasting their time searching for unicorns.

[Henry Schmidt]

Originally Posted by KNIGHTRACE

.....edit......Henry above encourages people who have to resort to using an MSD use the 6Al analog unit rather than the 6Al digital. I called summit racing and they no longer make the non digital version.

William , I like you and we've been friendly for years but why the onslaught of meaningless challenges? I'm not trying to fool anyone.

"Have to resort to using" where did that come from. I use MSD ignitions all the time.
I tried a number of digital boxes and found them inferior.

Both 6 series and "the all powerful" 7 series are offered with analog circuitry.
Wow look at that, it even comes in black....lol...

From Summit today.



You want a hot spark? Try running your MSD on 18 volts.....who knows, you might be able to weld with it....lol....

[LJ851]

Henry, I couldn't find pricing for your twin plug distributors on your website. Did I miss it or do I need to phone you?

[winders]

Well, I wouldn't even consider a CDI-based ignition system for any performance engine I would build today. I am using WeaponX ignitors and CoP sticks and get much better ignition performance than I could dream of with MSD.

I don't know why anyone here thinks that inductive ignition systems don't work on Porsche engines. The WeaponX stuff works great on 16,000 RPM motorcycle engines and could work on 18,000 RPM. So my 8,000RPM race engine is no challenge at all.

What we have here is someone living in the 80's.......when there is much more up to date information available.

[winders]

Originally Posted by LJ851

Henry, I couldn't find pricing for your twin plug distributors on your website. Did I miss it or do I need to phone you?

Get a twin plug distributor from JB Racing.......its the best one available.

[Henry Schmidt]

Originally Posted by LJ851

Henry, I couldn't find pricing for your twin plug distributors on your website. Did I miss it or do I need to phone you?

They are not on my website. We custom build each one to it's specific application.
Generally they cost around $ 2,200 and can take 3-6 weeks to build. We can build them using 2.4-2.7 point style distributors or just about any pointless 911 distributor.
They are a labor of love so they do not garner a lot of priority.

Oh....wait. I just remembered that we have two at my parts store, 911Vintage Parts ( 760-731-4911). I think JD may have one or two listed on EBay.
Both are CCW for 911SC based engines. One Marelli and one Bosch. We generally use the "Marelli" (Black cap) for <73 engines and the Bosch for later engines. It's only difference aesthetics but for most vintage Porsche guys, "period correct" has a lot of sway.

[KNIGHTRACE]

Henry, I consider us friends and we go back 25 years. I have always spoken positive about you and I feel you are misunderstanding me. I called Summit and asked for a MSD 6AL not digital. The man said they quit making it. Obviously he was wrong and too lazy to look. Let's try to stay friends and write this off as a misunderstanding?? We both have sent each other clients through the years, I would not want to compete with you on Mechanical injection vintage style builds. I think It is better we support each other and not try to compete with the others strengths as we both would probably loose at the other mans skill set. I am hopeful this is not taken wrong as I feel we both have a positive reputation and we both bring valuable information and help to the community.

[Henry Schmidt]

Originally Posted by winders

Get a twin plug distributor from JB Racing.......its the best one available.

That's the distributor that looks like it belongs on a hot rod, that uses an aluminum contact, plastic Jag cap and a bolt together rotor.....Right?

[Henry Schmidt]

Originally Posted by KNIGHTRACE

Henry, I consider us friends and we go back 25 years. I have always spoken positive about you and I feel you are misunderstanding me. I called Summit and asked for a MSD 6AL not digital. The man said they quit making it. Obviously he was wrong and too lazy to look. Let's try to stay friends and write this off as a misunderstanding?? We both have sent each other clients through the years, I would not want to compete with you on Mechanical injection vintage style builds. I think It is better we support each other and not try to compete with the others strengths as we both would probably loose at the other mans skill set. I am hopeful this is not taken wrong as I feel we both have a positive reputation and we both bring valuable information and help to the community.

No worries William ...... I have fun playing on the forums and try not to take it too seriously. I offer my experience and it's free. Those who don't want it, can seek advice elsewhere.
It's always a hoot to watch egos get in the way of community interaction. It's generally the ones with the least to offer (not you of course) who stamp their feet the hardest.

[winders]

Oh....so now you are calling JB Racing products crap.....nice.

[Henry Schmidt]

Originally Posted by winders

Oh....so now you are calling JB Racing products crap.....nice.

Winder, you are a strange little twist. Most Porsche enthusiasts couldn't care less about grinding away in a meaningless club event.

Every product has it's place. Period correct generally precludes billet applications.

As for the cap, they are shyt. We gave up on them Jaguar factory ran out of high quality ones. They can be fixed but I believe only Burnham Performance takes the time to machine them. But they are still aluminum contacts.

The quality different is there for all to see.

[KNIGHTRACE]

Henry I definitely have a large deficit understanding things written like text messages. I more often than not misunderstand them and maybe I am not good at what I write on the forum or maybe I am just too serious. I love humor and I do well in conversation but I am not good at it in what I write therefore I am super cautious not to sound offensive or like a bully and try to be respectful of others and I have the best of intensions.