Pertronix Install Questions, On a /6 with carbs... Options

[Allan]

Okay, I pulled the Crane unit out and picked up a Pertronix unit yesterday from GPR.

I was given 2 sets of instructions. 1 set came with the unit and Dave gave me a supplemental set.

The instructions that came with the unit just shows the leads going to the coil. Easy 2 wire install.

The set that Dave gave me shows the wires going to the CD box.

[Allan]

Here are the wires that were originally hooked up to the coil BEFORE I started screwing things up.

[Allan]

Coil & Pertronix leads

[Rouser]

What do you need the CDI box for when running a Pertronix? The CDI is for points-equipped distributors; can't see needing it with the Pertronix module.

[Allan]

What do you need the CDI box for when running a Pertronix? The CDI is for points-equipped distributors; can't see needing it with the Pertronix module.

(IMG:style_emoticons/default/confused24.gif) Beats me...

I just wanna get the thing running with the Pertronix first and THEN tackle the MSD install.

[Mike D.]

The six can run without the CDI box. you just need the power to the coil and the pertronix to the coil. Same way you would hook up a 4 cyl. with carbs. when you get that running then add the MSD. then the Pertronix goes to MSD and MSD goes to coil.


(IMG:style_emoticons/default/smash.gif)

[Cap'n Krusty]

Here's your answers. The CDI box requires a special coil. The one you show is NOT that coil. Given enough time, a conventional coil will eat the CDI. Been there, seen that. Maybe not today, or next week, but it WILL do it. The MSD requires a different coil. The CDI box improves the spark characteristics. 911s NEED enhanced spark, trust me. You have a kluged up mess there; obviously the previous owner or "mechanic" hadn't a CLUE what he was doing or how things are done in the modern world. (Hint: The Scotchlocks give it away!) I would cut to the chase and do the whole thing from scratch, and do it right. If you want to use the Bosch CDI, you'll need to buy the correct coil, then look at the wiring diagram posted yesterday. We can help you, but you have to want to be helped. If we give you the correct answers, and you keep asking 'til you get the answer you WANT, you're not gonna get it fixed, and we're gonna stop trying to help you. BTW, points often last 20-30K miles with the Bosch BHKZ (CDI) system. Long enough that subbing in a trouble prone Pertronix makes little sense. The Cap'n

[Allan]

Here's your answers. The CDI box requires a special coil. The one you show is NOT that coil. Given enough time, a conventional coil will eat the CDI. Been there, seen that. Maybe not today, or next week, but it WILL do it. The MSD requires a different coil. The CDI box improves the spark characteristics. 911s NEED enhanced spark, trust me. You have a kluged up mess there; obviously the previous owner or "mechanic" hadn't a CLUE what he was doing or how things are done in the modern world. (Hint: The Scotchlocks give it away!) I would cut to the chase and do the whole thing from scratch, and do it right. If you want to use the Bosch CDI, you'll need to buy the correct coil, then look at the wiring diagram posted yesterday. We can help you, but you have to want to be helped. If we give you the correct answers, and you keep asking 'til you get the answer you WANT, you're not gonna get it fixed, and we're gonna stop trying to help you. BTW, points often last 20-30K miles with the Bosch BHKZ (CDI) system. Long enough that subbing in a trouble prone Pertronix makes little sense. The Cap'n

Hey, wait a minute, yesterdays thread was regarding the Crane optical. I scrapped that and have moved on to the Petronix. The wiring you see (Other than the scotchblock was done when the six was installed (not by me btw).

I'm willing to try all the recommendations given but the situation has changed.

So (IMG:style_emoticons/default/tongue.gif)

[Mike D.]

On that note, go the MSD and Points. It will be easier...

[Allan]

Pulled the CD box. Here is the connector. B is 12v switched. Can I use it for my switched power and just cap off the 6v switched that was hooked to the coil?

[Allan]

And, my CD box doesn't have a D connection unless that's just the body of the unit to ground.

[ClayPerrine]

And, my CD box doesn't have a D connection unless that's just the body of the unit to ground.

That is the shielded wire braid that goes around the CD box wiring. One end attaches to a ground stud on the engine by the distributor, and the other end attaches to the spade connector tab above the 3pin connector on the CD box.

Without it you can get some weird crossfiring issues due to inductance from the plug wires.

And you definitely need 12V at the CD box.


BTW.. the Cap'n is right. You need the CD box or some kind of aftermarket spark amplifier to keep the 911 engine from fouling out plugs. They can be run for short periods without the CD box, but it willl misfire at high RPMs and foul the plugs something fierce.

If you don't need to pull the distributor for another reason, then don't bother putting in the pertronix. But the first time you need to pull it, I would put the pertronix in. My distributor had enough wear on the breaker plate that the points would not stay gapped. So I put the pertronix in and wired it up. I had 2 good CD boxes, plus the wiring for both, so I set mine up to be able to switch CD boxes by just moving a 30A ATO fuse from one holder to the other.

It also sets me up for dual igniton in the future!!

[Trekkor]

Pertronix, MSD 6AL and a blue coil. That's all you need for reliable sevice.



KT

[Allan]

Pertronix is already in the dizzy. I went out and started un-wrapping wires and have found this so far.

Please note that the red wire is actually pin B...

[Allan]

Just checked the coil and I'm inly getting 1 ohm. Petronix requires at least 1.5 for a /6 and 3 for a /4.

Gotta get me a new one now. (IMG:style_emoticons/default/dry.gif)

[Allan]

Here's the diagram for the MSD/Pertronix combo.

Where to I hook up the tach wire?

[MarkV]

If you are running the pertronix w/ a CDI, coil impedence won't matter to the pertronix. With a CDI the pertronix doesn't connect to the coil, it only acts as a magnetic switch. Same thing w/ points and a CDI, points only act as a switch, thats why they last 30k miles.

They make a pertronix that will work down to .6 ohms and won't fry if you wire it wrong or leave the ignition on when the engine isn't running.

[john rogers]

If it is a stock tach I think you'll need a MSD tach adapter to drop the coil voltage down or the tach will fry. If you use an Autometer (as I did) then you can hook it directly to the coil the same as with the stock 914 setup. If you have a timing light with tach built in it should handle the MSD signal fine, you can use it as a test to see where to plug in your tach.

[TimT]

I have no idea why you scrapped the Crane ignition. I set up 911 with a Allison (Crane) and MSD set up 12 or so years ago. The installation was easy, setting up the trigger was easy.

The pics your providing are showing some DAPO stuff.. Also you mentioned in a previous thread, that you were seeing 5V switched? is this still occuring? YOu need 12 for the ignition components to work

Throwing parts at a problem wont make it go away.

I would give some hand on help if I were on the left coast.

[Root_Werks]

Here's the diagram for the MSD/Pertronix combo.

Where to I hook up the tach wire?

Tach signal wire hooks to the little male blade terminal in the MSD box itself labeled "Tach Output"

I would go this route. Your tach should work without adapters with the MSD system. That 3 pin CD box was used, there is no telling how many miles it has on it and it's still close to 30 years old at best. Time for a newer system maybe?