I have a '75 6 conversion that was running a 2.7 with cis. My uncle did most of the conversion about 8 years ago and I can't find an ignition system (CDI box, MSD6AL)anywhere on the car.

So I am converting it to a carb'd 3.0, its running the '81 coil and the original distributor re-timed. What should I do for an ignition system? Do people run without a CD box?

Any advice on what others have put on their conversions would be greatly appreciated.

If you're running a 3.0, take advantage of it and buy a 6pin CD box. Your engine doesn't have points and even a permatune factory style replacement box with matching coil is a good system.

Or if you're on a budget, find a used 6 pin box/coil and wire it up.

After talking to Patrick motorsports and Rennsport, they both recommend buying a MSD 6AL and a high vibratory Blaster coil...

I do like the idea of a rev limiter... What do you guys think?

They both said that I will need something with the new magnetic coil, I guess you can get away with out using a CD box on the older motors (pre '77).

Or else, ditch the whole distributor/coil setup and contact Clewitt Engineering for an Electromotive crank fired ignition. Not that much more than you might have to pay for a Bosch CD box.

Listen to Rennsport. That set-up with a set of Magnacore wires will deliver more voltage to the plugs so's you can gap them to .05. They recommend this above bout anything else for a reason. You can spend a lot more money and not get as much spark.

While my /6 conversion is not complete the ignition system is purchased. I'm going to be running a 1978 3.0 in my 75 chassis with carbs. My ignition distributor is currently with Jerry Woods getting refurbed and recurved for carbs ( $500.00 ouch ) and I have purchased a Mallory 6AL CDI box. The reason I chose the Mallory over the MSD is the Mallory has a rev limiter that you set via a dial by useing a screwdriver, the MSD you have to purchase rev "pills " in various increments. Also according to Jake Raby the Mallory is a better quality unit over the MSD. I'm useing aftermarket plug wires,NGK plugs and I'll gap them at .040 and see how she runs. Unfortunately I have a long ways to go before turning the key

Thanks for the info guys.

Did you get the 6853m? Did you get a tach adaptor?

http://store.summitracing.com/partdetail.a...mp;autoview=sku

I always thought MSD was better, but I bought their Hei distributor for another car a few months ago and some of the parts on it looked cheap...

I purchased model # 6853M but no tach adapter but I'm replacing the 4 cylinder tach with one out of a 911 for the six. To my knowledge one isn't needed. My mechanic has installed many MSD's and says most of the time a tach adapter is not needed. I don't fully understand the electrical requirements converting the 4 to a 6 but I'm leaving the wiring up to the mechanic. I also purchased a 6853M for my 911 but haven't gotten around to installing it yet. My hope is both cars will be running the Mallories and I'll keep the OEM Bosch 6 pin CD as " backup ".

On my conversion, a 3.0 RS spec motor I'm using the Porsche electronics in the distributor which feeds a MSD 6AL W/ 7000 rpm chip. Also have the MSD tach adaptor (pn 8920), and the timing control (pn 8680). The timing control lets you advance or retard the timing by the turn of a knob. Set the timing with the control box set half way and you can get 7 1/2 degrees of retart/advance. I'm using 8mm plug wires, Bossch W5DC plugs gapped to 35 and a MSD Blaster coil.
I would guess that a '75 distributor used points and the Bosch CD box. At least that is what my orignal factory six had in '70. I'm not sure when Porsche went to electornics in the distributor.
I've never had a problem with my setup. If your dist. has points, I would suggest you use something like a Petronix Ignitor to trigger a CD box.
I mounted the MSD boxes (3) behind the seats for heat reasons. Although, have had them mounted in the engine bay and didn't have a heat problem there. Anyone wanting to see my mounting, PM me your email address and I'll send you a pic.

The 3.0 dizzy has a built rev limiter on the rotor....unless someone cheaped out and replaced it with the non cut out version.

The Bosch CD box is the best system out there and the other systems are for the most part cheap knock offs. My business partner rebuilds the Bosch units.....I have two 3 pin and two 6 pins available. If you need them.

Don't think I would trust a 33 year old cutout type of rotor unless it was in perfect condition (weak spring, rust/corrosion). I really don't think that they are that consistent either. Why trust a not so perfect part on a very expensive engine?
Just my thoughts...............

Why would you be using a 33 year old rotor?

He bought an engine that had never been tuned up ..............

Sounds like you...but younger.....

The rev limiter is in the rotor? I thought it was in the CDI box? What does it limit it to?

I like the idea of putting the 3k rpm chip in the car (msd) in case you drop it off at a shop or maybe do some mpg testing...haha.



rfuerst911sc- Is it hard to know what rpm you set the mallory rev limiter to? I would think that its hard to see the adjusting screw once its mounted in the car. I think the mallory is also digital and the MSd is not.

Justin, look at the rotor. The cutout rotor is not straight across like a regular one. It uses a spring and as the rotor spins the centrifugal force pulls on the spring. On the four cyl. at approx. 5850 rpm the rotor "grounds" the rotor and cuts out the spark. It does it on ALL cyls. Keep in mind that the MSD cuts out ONE cyl. randomly at a time to keep from loading it up with fuel. Even new, the cutout rotor does it at the "approximate" rpm. I think I would trust a cutout using electronic means of "counting" rpm rather than mechanical using a certain tension spring. The rotor should have the cutout rpm engraved on it.
I have the 6-7000 chip kit. They go from 6000 to 7000 rpm in 200 rpm increments. It's nice to be able to get a little more rpm at a track when you need it and know it IS right. Plus, the valet/teenage son chip it cool too!!!!!!!

When I was running a 3.0 in a 914 the rotor limiter worked fine. It was a euro version and it did it's job at 6800 rpms, juts like what was engraved on it.

Do what you feel is right for you but I tend to take the oem route while others think aftermarket parts are better.

As to the tach....I needed an adapter the one time I used a MSD unit.

Does that mean that you used points to trigger the CD box? If so that is fine because points last much longer doing that rather than using a condensor and just firing the coil.
If electronic means of ignition wasn't an improvement, car makers around the world would still be installing points in their cars!!!!!!!!! I'm not saying that '70's era oem ignition isn't reliable, but that was 30+ years ago and improvements have come along.

I haven't installed the Mallory yet because I haven't installed the engine yet When looking at the Mallory on one end you have all the wires coming out and on the opposite end you have a small cover held with two screws. The rpm adjustment is under this cover. So I guess depending on how you mount the box will answer how easy or hard it is to adjust does that make sense? And yes the Mallory is digital and also has a anodised housing rather then a painted one like MSD.

I've put in a couple Crane systems, it's late and I can't recall the model, but they have a nice adjustable rev limiter feature, and you can get an optical trigger set up for the pre 3.0 distributor and eliminate points. I don't know what you've got to do to hook up the 3.0 distributor, as both the installs I did were on earlier engines.

From beginning to about 1977 points were used to trigger a 3 pin CDI box. Passes less voltage thru the points .... last longer.

In 1978 with the advent of the 3.0L ... the distributor rotates in the opposite direction and magnetically triggers a 6 pin CDI box.

According to the website you need a $110 tach adaptor for the VDO gauges... I hope thats wrong...

http://www.malloryperformance.com/pdf/6852M_6853M.pdf