Should I go pertronix or go with points?

[Eli]

I tracked down a distributor for my 911 E 0-231-159-006 and it has a pertronix electronic injector already on it.

Should I go with that which will require a new coil or should I go with points and keep my car old school?

[mobius911]

I've heard that the timing on the Pertronix can vary up to 6% from cylinder to cylinder- differences in magnetic field strength cause the triggering to occur earlier or later than desired (someone measured it in a thread I read somewhere). That and they seem to die unexpectedly. I vote old school if you like the ultimate state of tune. Maybe points are a pain to set up, but once you get the gap (as measured by a dwell meter) right, points seem to be pretty damn solid.

[Eli]

That is what I was leaning towards, the car had a defunct cis on it from the PO and I took it back to MFI. I have fresh points already from my previous distributor curiously it was a 0-231-121-006 which is for early 911 up to 68. I will have to get a condenser for it.

When you buy a condenser does it come with a mounting bracket?

[mike curnow]

I am very interested in this thread. I was going to change my 4 point Morelli to Perironix. Do we have any real proof that they are off that much? Seems to me almost all current cars use solid state distributers, are they off also? Do they use a different system? Who is the source of this " I heard " that Perironix is off, how did they measure it?

Mike

[mobius911]

Should have guessed someone would want to see the source... I found it, over at Pelican. Here's the post by the guy that did the testing. I have worked on the development of a diagnostic system based on small permanent magnets and we experienced the same issues with variance in field strength. These little magnets are hard to get exactly matched. This guy's test methodology seems spot on:

"Prebordao; Find someone with a pertronix unit and take a timing light with adjustable timing dial. Connect to all 6 wires and spot using the marks on the pulley. Porsche marked for all cyl. Note the variance. Alternatively find someone with an old distributor machine to test before you install in the car. The fault with these lies in the fact the 6 magnets are of varying strength and will trigger at slightly different distances to the hall effect sensor. I swapped the magnets inside to diagnose to cause of the problem and the variance followed the specific magnets. Lead to slightly reduced power and lumpy idle.
Properly installed and lubed points on a good distributor will give years of service with the CDI system"

The full thread at Pelican can be found here. Check it out. You'll hear from the lovers and the haters in all their glory and can make your own decision.

Oh, and I would expect that anything based on an optical trigger wouldn't experience these variations in timing. This issue is probably limited to Hall effect types.

Jeff

[MTemp]

I had my distributor tested on a King test rig (see photo) at BS Motorsport in the UK. 3 of the triggers were spot on, the other three between 1 and 2 deg off. Contacted Pertronix and they said that was within their manufacturing tolerance. Have run with it since and have not seen any problems, and the stock 2.0 (with PMO's) produced 145bhp at the flywheel on the dyno run so I doubt it's causing too much downside.

Mick

[304065]

Nice Photo Mick! I love those King machines. Wonder how bad the points would be off?

Mike Curnow, "modern" cars have a much bigger trigger wheel, either on the crank, or using the flywheel itself (964-) which reduces the effect.

Any hall effect trigger works on the principle that the magnet passes by, induces a voltage change in the conductor, which is run through a gate and an amplifier to switch the ignition. Pretty simple.

Pertronix is kind of "backwards" inasmuch as you have six magnets moving-- some hall effect systems (early Bosch for example) have a single fixed magnet which is then interrupted by a metal shutter with slots in it. The uniform size and spacing of the slots gives you an accurate trigger.

Here is an example:



I haven't tested mine (or the "Hot-spark" clone with active dwell control but report back here.

[kentf14]

FWIW, I've got a Pertronix in my car and have never had an issue with it.
Also, Pertronix does not require a different coil.

[Eli]

After reading the thread on the bird about pertronix, it is settled. Pertronix are great and a great update and they are crap made in China.


Ken are you sure I can run a pertronix on a 1969 E without changing the coil?

I just want to get my car running.

[304065]

FWIW, I've got a Pertronix in my car and have never had an issue with it.
Also, Pertronix does not require a different coil.

Are you using the Pertronix to trigger the stock Bosch CDI in your '73? Of course that would use the same Bosch CDI coil.

If you use the Pertronix on an SWB car it makes sense to change to a coil with a lower primary resistance, so it will charge faster. The original SWB coil was 2,1 ohms with a 0,9 ohm ballast resistor, for 3 ohms total, or 4A through the points, their max. These days the solid-state transistor in the pertronix can probably handle 7-10 amps, giving you more ignition energy particularly at high RPM.