There was a thread a while ago that discussed this, and answered questions, but it never got down to step-by-step instructions. Thanks to Graham for the basic information.

These instructions assume that you are keeping the switch box and original coil. If you want to use a hotter coil and higher voltage and bypass the switch box, I believe that you will need to wire it per the Pertronix instructions and use a resistor to calibrate the tach, otherwise, it will read too high.

The first thing that you notice about the Pertronix instructions is that they assume that the points connect to the negative side ("1") of the coil and that power from the ignition goes to positive ("15"). When you look at the 107 setup, however, you will see that 1 is grounded and there is a wire from resistors to 15. This is because the transistor box that the 107 uses switches the positive side to trigger a spark from the coil.

Installation.

1. Remove the points from the distributor and unhook the green wire with the tab that the points connect to.

2. Follow the green wire to the terminal block (two connections) on the fender below the ballast resistor. Note it for a future step.

3. Tape the connector on the end of the green wire, coil the wire up, and tuck it somewhere out of sight, like behind the coil, if you want to keep the points as a backup. Otherwise, just cut it at the terminal block.

4. Install the Pertronix magnet and shutter in the distributor.

5. Crimp/solder an appropriate connector and connect the red wire to the front terminal on the lower ballast resistor. This is where 12V comes from the ignition. There should be a red/black wire running to it.

6. Prepare black wire and connect it at the same terminal where the green wire from the coil connects.

7. Install rotor and cap. Start car and check timing.

Pictures attached.

Attached Thumbnails

   

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks for posting this Chuck.

Just looked at my car and in fact, I connected the red wire to the other side of the 0.4ohm resistor. I don't think it matters. I measured voltages and switch side was 13.7v and the side I connected to was 11.97v. Probably lower once voltage reg drops charging voltage.

One other thing I did, was run a ground wire from body of distributor to negative of battery. Just to make sure distr was properly grounded. This was suggested in an earlier thread.

Picture attached of resistor (RED) & BLACK wire attachment

Attached Thumbnails

 

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Pert Module wants FULL battery voltage to the module so that when starting, the electrical systems draw down from the starter circuit does not adversely effect the modules switching circuitry. The Pert Switching circuit [ transistor and amp/module] requires a seperate power feed of 12v in order to work effectively. This 12v has nothing to do with the coil circuit. The reason for the ballast is not for power to the PERT module... it is there to balance the coils Primary Circuit Winding resistance as to not burn up the switching transistor/module due to too high an amp load condition that a too low of resistance coils primary winding will put on the module . That is where/why the ballast comes into the circuit..ballast is not on Pert Modules 12V supply, but added to the coils primary winding [ in series ] to attain the proper Resistance of the primary coil circuit for the Perts specs.............that varies with the number of cylinders. If one gets the recommended Pert coil, the ballast is coil internal to protect the module circuit .
It is ony the black wire to the distributor , from the coil, that is switched..[ by the modules transistor] ..and that is to the ground of the dist. It is a 'Switched Ground Circuit'. [ same as the points were]. That is the coil primary circuit completion and has nothing to do with the power feed to the Perts module..two different circuits. One circuit requiring a ballast [ either internal coil type or external] and the other circuit requiring a 12 V supply.
The 12v to the module is the modules power supply in order to make it work b/c it is an Electronic Switch, not an Electrical switch..meaning it needs a power supply to the Modules IC circuit that functions/activates the switching transistor . And a ballast on that 12 V. feed will hinder the modules output.
They will work with the lower power, but not as well..as you know , Pert is hall effect principle and any hall effect sig is dependent on RPM for sig amplitude...so, a weak module feed results in a weak sig, specially at start-up where both the starter draw down on the battery [ as low as 8/9 V on some cars] and the low rpm of the magnet/reluctor [ due to low starter cranking speed] for hall effect come into play. Results can be both hard starting and weaker spark under stress/load conditions.
The reason for the Benz SG switching on the Positive side [ w/neg side of coil grounded to chassis] was b/c Benz wanted the points to be on the low amp draw side of the circuit ..as they still used points, and by using the points to switch the SG/transistor circuit rather than the coil ground, the points contact surface would last longer... as it was now the SG transistor that would handle the coils amp load, not the points... as the early system did.
But , all was in Vain b/s they found that any oil/dirt/corrosion on the points would nor burn off b/c of the low amp/volts across them, and even with the switchgear having a transistor, you still had mechanical points switching the switching transistor circuit...so it accomplished nothing, as the true fault was always the inefficencies and lobe/block wear of mechanical switching ...meaning Benzs Transistor Ignition was not a true Elecronic System, it was kinda half and half, still using points, but attempting to get some life out of them by using them in the low amperage part of the circuit, and using a transistor switchgear to handle the high amps of the coil primary circuit.
It is the Hall Effect Principle Tech advance that finally got ignition systems to be classisfied as true Electronically Switched ignitions..thus completely eliminating the use of the mechanical points. Benz was late on that one.............and that one was a big change for not just the Auto Industry, but for all IC Engines ignitions .....for sure....
Even now with the new, high tech ignitions of full electronic FI cars that don't need distributors [ DIS system] and rotors and plug wires, etc b/c the triggering is done by computer driver circuits, the main trigger input to all circuits is still the Hall Effect CPS sensor...so, that Principle is still used in the switching sensors......

On the Pert, [ or any hall effect point conversion system] ,one can envision the module circuit simply replacing the dist cam/block mechanical function/parts, and the transistor replacing the point contacts..two seperate functions in the sense that the transistor is still just ground switching the coil to the dist plate just as the points did, and the magnetic flux of the module and reluctor/magnet sending an electrical trigger signal to that transistor at the correct time instead of a cam/block mechanically doing the same thing by open/closing point contacts. The coil could care less how it's negative side gets grounded to the dist base for circuit firing, be it mechanically or electronically..........just so long as that black wire gets to neg/ground to fire the coil when the piston is at the right place...
The only difference is in how the Coil gets switched ..mechanically or electronically.. and mechanical switching is now history.

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A Dalton

Good information Arthur.

When I connected my unit, I did not know which side of 0.4ohm resistor was the feed from the switch, so I checked with voltmeter - the first terminal I checked was 12V, so that seemed to be good And it has worked fine, just the slightest of delays as the engine spins up as compared with points, but that is expected.

Pertronix specify that their module will work from 8 - 16v. Not sure what max voltage out of alternator would be with a low battery, but I guess it should be well below 16v and not damage the electronics. Don't know how low voltage goes when engine is being cranked - will have to check that!

I moved the connection over to the higher voltage terminal, but no noticeable change. Voltage probably does not affect the transistor which can really only be on or off, so long as it is in the design range. But I am no electronics expert! Changed it anyway!

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

As I said , they will work with the lower V, but not as well..
The Best set-up for Pert is to use their Pert-1 with direct 12V ignition sw feed and their coil to match..and then to put a kill sw for module protection in case Key ON/Engine OFF situations..like working on the car.

As I started to write that piece, I kept going on with the additional FYI for the benefit of those who are not familiar with the general workings of Hall Effect principle and the advantage of point conversion, and I felt the Vintage section is a good place for this info to reach the Archieves b/c so many of the Vint cars were point ignitions....
Most members here have already done this mod, but one will notice thay all keep the old points "neatly tucked away" somewhere for originality, but the points never go back cuz they just can't compare....as I said..History and the way of Horseshoes....
*Note
There are a few dis-believers that stay w/points..but that is their problem.
Another mod that I have used for guys that do want to stay with the point system and have the early system w/o Ballast by-pass is to simply install a relay to by-pass the ballast resistor while the key is in the crank/start position. This simple mod helps a lot to remedy the problems associated with weak ignition due to starter circuit demand/ voltage drop at start-up.
One will notice that in the late '60s, Benz Finally changed over to a Ballast By-pass circuit using an extra terminal at the starter solinoid to get past the ballast during starter crank... [ making up for the V drop @ Ign during crank]..this mod does the same thing w/o having to change the starter.. but I recommend the newer starter on the basis that along with the extra by-pass terminal, the torque also went up on these starters [from .8hp to 1.5 hp] and that feature, combined with the ballast by-pass for full battery to ignition at crank was a great improvement for starting conditions.
Just another worthwhile change for vint chassis.. my upgraded starter and Optically Switched ignition 250sl starts like my E320..Instantly.
And I consider neither of these modifications to hinder the Vintage Status of the car..I consider them to be Driver Enhancements and I drive mine all the time. Had these Tech advances been available at that time , they would have been standard components.

And if one is using the Pert on an early chassis with the low torque starter, just changing to the higher torque starter alone will greatly help the Pert b/c being Hall Effect , the Perts signal strength [ amplitude] increases with the higher cranking rpm of the newer type starter...

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A Dalton

Arthur,

Seeing that this is becoming a Pert FYI, I have a question.

Our early cars had copper plug wires with a resistor at each end and used non-resistor plugs.

Because of availability and cost, some(many?) of us have installed new Bosch Ultra Opti-Layer copper core. This is what Bosch now recommends for Mercedes V-8s of our vintage. (They measure about 1.5 kohms end to end as opposed the OE wires that were more like 6.6 kohms) . These wires are usually used with resistor plugs like the WR7DC.

Let's not re-open the resistor plug discussion here, it is well covered elsewhere

Many domestic applications for the Pertronix module and Flamethrower coils would have carbon core wires. These wires have higher resistance (3-12kohms/ft) as compared with the MB OE (6.6kohms or the newer Bosch wires&plugs(1.6kohms + plug)) (my measurements!)

Given the higher output coild, would this difference in wire resistance affect the engine performance or perhaps dictate a different type of plug than the OE ones or popular current equivalents?

In other words, if we deviate from the original design, should we not have a complete system that someone has engineered to suit the engine - coil, wires and plugs?

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

This is where there is much dis-agreement and even the manufacturers disagree.

Which is why most guys will not use the Pert 2

But ,to save all the concern and argument , I will only state what I have done on Vintage cars with sucess since the demise of Non- R plugs.

I find that copper core wires w/o resistor plug connectors on the plug end and R plugs work fine. The R factor on the other end is the Rotor . The advantage here is you can now use the R plug , have the advantage of solid wires, and have R factor equal to all plugs , regardless of plug wire length.
I make my own wires and buy it buy the meter.
Some guys still use the plug resistor ends with the new R plugs, but they go with the 1K version over the 5K ones . I have not used either when using an R plug , but all of this is in experimantal stages with my own cars.
I do not like the Pert, so I am a Crane fan..but that is only my preference b/c I do not like Hall Effect sine wave over optical switching...but that does not change the secondary R factor to any degree when addressing the Plug/Wires change..
The BEST performance I have been able to attain [ and this is with the aid of gas analization and ignition DSO scoping for verifications] , has been with
solid copper wires, original 1K plug connectors , and NGK NoN -resistor plugs.
That would be on a Bosch MFI set-up. I had almost the same results with R plugs, solid wires and no Resistor plug connector ends.

I LOVE NGK plugs in old Benzs......and I been doin' dis' stuff for a looooooong time...........

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A Dalton

I have had my Pertronix working well while still retaining the MB switchbox for several years now. I kept it this way so the tach would work.

Has anyone had any success converting to Flamethrower (or equivalent) coil, bypassing MB switch gear AND still keeping a working tach.

I know this has been discussed, but I have not yet found the answer.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I'm trying to do this now, and having some trouble. If this is already covered somewhere else, my appologies, just point me there.

My ignition box seems to overheat after about 30 minutes of use, causing the engine to shut off immediately. This is the reason for the bypass (plus the steep price for a replacement box from MB).

It's a W114, and it I plan to install Pertronix once I get it running with the existing points.

Where I am at:

I have run the green wire from the condenser to the neg side of the Bosche blue coil, and I have redirected the red ignition (+) wire from the box to the pos side of the coil. I have also hooked up the existing ballast resistor, which has the "factory starter bypass".

I'm getting spark, and it kicks abit first turn, but then just floods.

A couple if ideas I have:
1-could timing be that different? If so, that could be my problem.
2- Is there any intelligence in the fuel circuit that may be confused now that I am not using the transistorized ignition module?

Cheers,
Michael Schroeter.

Have to agree with Arthur on this one guys.

1) don't use Pert 2, you don't need it and it's more 'fragile' anyway (the distibuter I used recommended that I didn't use is or even think about it - which considering they could have made more money, I thought was interesting advice).

2) the Pert 1 requires full voltage. I bypassed the MB ignition system entirely but left it in the car as a back up (I have a spare set of points in the boot/trunk). I did actually fit a flamethrower coil as well though so I don't know if that would make a difference to the wiring.

Suffice to say once timed the car hasn't skipped a beat and runs better than ever. I suspect this is a lot to do with the hall sensor compensating for the bit of distributer shaft shake which it has. All round a good result as the distrubter is a very expensive bit of kit as it contains the trigger points for the D-jet.

The only down side is you need to remember not to leave the ignition on without the engine running as this can fry the module apparently. I may fit an interupter switch on the live feed in future to allow for ignition on 'tinkering'.

It's been on the car for over a year now and, out of habit, I've re-checked the timing on at least two occasions - it's never shifted at all

Hope this is of some help.

J

To get it running with points, you need to disconnect the lead from the box and run 12V off the ignition switch to the + side of the coil. You can use a jumper from ignition switch side of the first ballast resistor. Leave the green wire on the - side of the coil, and it should start.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks for your feedback Chuck.

I've got good spark. Seems to want to start for 1 second, then no kicking. Then flooding. Bosch D-Jetronic system.

I pulled 2 injectors out to watch the pulse, and it starts nice and short pulse, then about 1 second later, long/heavy pulse.

There was fuel in the throttle position sensor area, could this have damaged that sensor?

I was also wondering if the injector trigger contacts in the distributor may be mucked up from flooding?

Just looking for suggestions.

Best Regards,
Michael Schroeter.

I doubt you could damage the TPS - It is on outside of throttle housing.

Trigger points are a possibility. I had this happening on my SL. The fiber cam followers had worn down and the points were staying closed for almost a full revolution. As a result, the injectors were firing at the wrong time and for too long. If you open the distributor up and look at the trigger cams, you can see how they work.

When I had a similar problem, I took the distributor out and tested it on the bench. If you connect an ohmmeter from the center contact to each of the others in turn, and rotate the distributor, each set of points should stay closed for about 110 deg or so. Or at least thats how my good points are. I wish I had had an oscilloscope or a scopemeter, but the ohmmeter did work.

If they don't test out, you may need a new set of trigger points. But they are VERY expensive. Used sets may be as bad as the problem ones unless they come out of a known to be good running car!

I have an idea on how we could adjust the trigger points. If you are interested, it might spur me to do it and take some pictures!

PS: We have got off-subject - maybe we need a new thread - Testing Trigger Points?

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Hi Graham,
I'll start taking my distributor appart. I'll take pictures also.

I'm very interested in you idea on "adjusting trigger points".

I'm a bit new to this forum, but I'll try to start a new thread here in a moment.

Cheers,
Michael Schroeter

uggh pertronix. What was the actual problem?

__________________
Pierre Hedary 1985 280SEL, 1970 111.026 in progress
Mercedes technical advice hotline: 407 765 2867
[servicing older Mercedes in the state of Florida with competence and passion].

From the standpoint of an honest MB technician, Vegetable oil is a threat to your diesel engine's mechanical integrity.