72 850 Pertronix Info

Heed the Pertronix website! First, see if they have an Ignitor (I, II or III) for that particular distributor. Then measure the primary resistance of your coil: If you use the basic Ignitor I, it needs a coil with at least 3.0 ohms primary resistance (inclusive of ballast resistor if your car has one). The Ignitor II or III systems however should use a "high-energy" type coil with about a 0.6 ohm primary resistance.
To go with my Marelli S118 distributor I got the basic Ignitor I because (a) it's cheaper than the fancier variants, (b) I can use my existing Marelli coil which happens to have a 3.6 ohm primary resistance; and (c) I can keep my points and condenser in the glove box as spares (they would burn out if used with a low-resistance coil).
Just received the Pertronix in the mail today so haven't installed it yet. Will report back only if it doesn't work right :)
 
DSpieg said:
Heed the Pertronix website! First, see if they have an Ignitor (I, II or III) for that particular distributor. Then measure the primary resistance of your coil: If you use the basic Ignitor I, it needs a coil with at least 3.0 ohms primary resistance (inclusive of ballast resistor if your car has one). The Ignitor II or III systems however should use a "high-energy" type coil with about a 0.6 ohm primary resistance.
To go with my Marelli S118 distributor I got the basic Ignitor I because (a) it's cheaper than the fancier variants, (b) I can use my existing Marelli coil which happens to have a 3.6 ohm primary resistance; and (c) I can keep my points and condenser in the glove box as spares (they would burn out if used with a low-resistance coil).
Just received the Pertronix in the mail today so haven't installed it yet. Will report back only if it doesn't work right :)
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I sorta cheated on mine. I got the Pertronix unit and the coil directly from Pertronix.
When I installed it I pulled the coil/bracket/resistor and replaced it with the Flamethrower coil and a new bracket.
If I carry spares I'll have points, condenser, the Marelli coil, resistor and the original bracket, and the wire that runs from the distributor to the coil.
I made several changes (see earlier post) in addition to the Pertronix so I can't attribute all of the improvement to it, but none of my 850s or 128s with the stock ignition ever started like this car does now.
 
gene cooley said:
I made several changes (see earlier post) in addition to the Pertronix so I can't attribute all of the improvement to it, but none of my 850s or 128s with the stock ignition ever started like this car does now.
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Hi gene,

When I redid my 124 sedan's ignition with the Pertronix unit and Flamethrower, those were the only items I changed. The car was transformed IMHO. It started much easier and ran better in general. Just reporting my experience to let you know it was obviously your new Pertronix ignition parts that improved the starting. ;)
 
JimD said:
Hi gene,

When I redid my 124 sedan's ignition with the Pertronix unit and Flamethrower, those were the only items I changed. The car was transformed IMHO. It started much easier and ran better in general. Just reporting my experience to let you know it was obviously your new Pertronix ignition parts that improved the starting. ;)
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I think you are right. When we made our changes it started with a few cranks while we chased the timing but once we had it set it fired instantly. We let it sit for a week because I had other projects. When we went to start it again I ran the fuel pump for a few seconds, hit the gas about twice and it was running almost before the key hit the stop.
This is an engine that usually took about 20 minutes of fiddling to even get it to fire. I'd say the $200+ that I have in the Pertronix, coil, and some related wiring was well worth the money.
 
JimD said:
Hi gene,

When I redid my 124 sedan's ignition with the Pertronix unit and Flamethrower, those were the only items I changed. The car was transformed IMHO. It started much easier and ran better in general. Just reporting my experience to let you know it was obviously your new Pertronix ignition parts that improved the starting. ;)
Click to expand...

Jim, I reread your post and thought about this a little bit more and decided that I have a real problem.
My gear drive starter arrived from MWB yesterday and now I have to decide whether I should put the old plugged up carb back on or go back to points so that I have a reason for a new gear drive starter.
Always something.....
 
Well, I'm baaaackkkk..which can only mean one thing - the Pertronix MR-LS3 didn't work in my 850 Spider. Installed it carefully per instructions last night, it fit fine, but no spark. Took it out this morning and re-installed the old-fashioned points and condenser, car fired right up. A 'pointless' experiment.
 
DSpieg said:
Well, I'm baaaackkkk..which can only mean one thing - the Pertronix MR-LS3 didn't work in my 850 Spider. Installed it carefully per instructions last night, it fit fine, but no spark. Took it out this morning and re-installed the old-fashioned points and condenser, car fired right up. A 'pointless' experiment.
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Your spider has a Ducelier distributor or a Marelli? The MRLS3 I believe is for the Marelli. The Ducelier uses the unit which has a magnet ring as I recall.

Edit sorry went back to read your original post. You have the Marelli so the MRLS3 would be the correct unit, my apologies.

Perhaps the unit was defective or it won’t actually work with your existing coil.

Bummer anyway.
 
DSpieg said:
Well, I'm baaaackkkk..which can only mean one thing - the Pertronix MR-LS3 didn't work in my 850 Spider. Installed it carefully per instructions last night, it fit fine, but no spark. Took it out this morning and re-installed the old-fashioned points and condenser, car fired right up. A 'pointless' experiment.
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Before you give up call Pertronix. I bought mine directly from them and the person that took my order seemed to have both knowledge about the system and info availabe on my "odd" S156AX Marelli distributor.
Mine uses the "ring" over the distributor cam.
Did you unhook the resistor and does your coil match the Pertronix requirements?
 
Hey Karl and Gene, my 850 has a Marelli S118 distributor (with the centrifugal advance plate at the top, above the points). My coil has a primary resistance of 3.6 ohms, which should have worked (I think) with the MRLS3 that requires a minimum of 3.0 ohms per Pertronix. I do NOT have a ballast resistor in the circuit. I did buy the Ignitor directly from Pertronix, so will call them if I decide to pursue a return-for-refund; but in the meantime I've offered the unit to a friend who has just completed his own 850 Spider restoration and was contemplating the Pertronix as well - he's an electrical wizard so if anyone can make this thing work, he can.
 
DSpieg said:
Hey Karl and Gene, my 850 has a Marelli S118 distributor (with the centrifugal advance plate at the top, above the points). My coil has a primary resistance of 3.6 ohms, which should have worked (I think) with the MRLS3 that requires a minimum of 3.0 ohms per Pertronix. I do NOT have a ballast resistor in the circuit. I did buy the Ignitor directly from Pertronix, so will call them if I decide to pursue a return-for-refund; but in the meantime I've offered the unit to a friend who has just completed his own 850 Spider restoration and was contemplating the Pertronix as well - he's an electrical wizard so if anyone can make this thing work, he can.
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Let us know even if it does work. It's good info to know why it didn't work for you.
 
DSpieg said:
Hey Karl and Gene, my 850 has a Marelli S118 distributor (with the centrifugal advance plate at the top, above the points). My coil has a primary resistance of 3.6 ohms, which should have worked (I think) with the MRLS3 that requires a minimum of 3.0 ohms per Pertronix. I do NOT have a ballast resistor in the circuit. I did buy the Ignitor directly from Pertronix, so will call them if I decide to pursue a return-for-refund; but in the meantime I've offered the unit to a friend who has just completed his own 850 Spider restoration and was contemplating the Pertronix as well - he's an electrical wizard so if anyone can make this thing work, he can.
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Could you scribble up a diagram of how you wired it and send us a pic?
 
Too simple to even need a diagram - red wire from the MRLS3 to the (+) terminal of the coil, and black wire to the (-) coil terminal, as specified in the included instructions.
 
DSpieg said:
Too simple to even need a diagram - red wire from the MRLS3 to the (+) terminal of the coil, and black wire to the (-) coil terminal, as specified in the included instructions.
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Sounds like it should have worked.
I took a picture of ours (please remember that this thing has been sitting for 10 years and it's dirty in there). On the (+) side 2 blue wires are power in and continues to somewhere. One white wire is power to the Pertronix red wire. The other is power to the fuel pump relay.
The (-) is Pertronix black wire and the tach signal -- brown wire.
Ours is working fine, guess that you must have a problem in the Pertronix unit. I'd still call them and ask before you try it on another car.
20190717_154157.jpg
 
I added up the cost of all the repair parts we bought in the last month. I shouldn't have.
Looks like the Pertronix and related parts, (coil, bracket, wiring, cap/rotor), the fuel system and related parts (carb rebuild, fuel pump, relay, hoses and wiring), new battery, gear drive starter, came in at just under $900. Might have missed something.
Not done yet....brakes still to do.
At least my son and I are splitting the cost.
 
I was looking for an oil pressure sending unit to replace the "bad"? one in the 850 and I came across this box of 850/600 brake and suspension bits. Sometimes you can save too much stuff....
I did find the oil pressure sending unit in another bin, it was bad too. Something else to add to the list.
20190731_140127.jpg
 
Lots of good useful things in there.

All the things that some have just thrown away, they will come in handy or be a saleable set.
 
DSpieg said:
Too simple to even need a diagram - red wire from the MRLS3 to the (+) terminal of the coil, and black wire to the (-) coil terminal, as specified in the included instructions.
Click to expand...

Any follow up on this? Did it work on the other car or did Pertronix have an answer?
 
Hasn't been tried on my friend's car yet, and I'm not planning to call Pertronix until he gives it the independent test (to rule out 'installation error' on my part).
 
Not related to the Pertronix, but the alternator wasn't charging. Cleaned the wires on the alternator, didn't help. Pulled the regulator and every connection was rusted. About 30 minutes with a wire brush, file and some needle nose pliers to tighten up the connectors and its charging again.
 
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