72 850 Pertronix Info

Discussion in 'Rear-Engine Fiats' started by gene cooley, Jun 17, 2019.

  1. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    I am taking my 72 850 out of storage and getting it back on the road. I read what I could find on Pertronix Ignitions (+ and -) and have decided to go ahead and give it a try.
    The distributor is a Marelli S156AX.

    Ignitor or Ignitor II?

    Pertronix matching coil or any good quality coil?

    Plugs?

    Does anyone keep these in stock? Jegs and Amazon (from Jegs) are saying there's a 3 week wait. I'm hoping that a Fiat supplier might keep some on the shelf.

    Thanks.
     
  2. kmead

    kmead Old enough to know better

    Location:
    Michigan
    Either the MR-LS2 or MR-LS3 the LS3 deals with dwell better apparently.

    AutoRicambi has them in stock. Same kit for early block mount distributors on a 124 as the 850 apparently from the many listings I have perused.
     
    BrettM likes this.
  3. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    Thanks. I'll start there and get one ordered.
     
  4. NM850

    NM850 True Classic

    Location:
    Albuquerque NM
    Any good coil will work. I use Bosch. Plugs, I like NGk BP6ES
     
  5. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    Thanks for the coil and plug info.

    Looks like my Marelli distributor
    (S156AX) is a European model. Rather than picking another one off the shelf in the garage it's been recommended that I just buy straight from Pertronix to match the distributor.

    Thanks to MWB for the distributor info.

    Looks like it's time to spend money....
     
  6. NM850

    NM850 True Classic

    Location:
    Albuquerque NM
    Take the distributor out and check the play on the shaft. They get worn and it causes erratic timing.
     
  7. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    I checked when I put it (back??) in the car. It's in good shape. I'm not sure if it came with the 850 or in a box of distributors I got with the 600.
    Someone must have bought it as a replacement part. Don't think it's been used very much.

    Pertronix Ignitor II and coil are on the way by air from CA to VA.
     
  8. JimD

    JimD Waiting for Godot... Moderator

    Location:
    Missouri, USA
    I put a Pertronix MR-LS1 and matching coil into the distributor for my 124 sedan's 1438 OHV. I was very happy with the results and the car is still starting and running better than pre-Pertronix. I did have some issues getting the unit bolted into my distributor, but nothing insurmountable.

    Good luck!
     
  9. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    Apparently Pertronix is Flamethrower so my coil is some variation of that.
    My distributor uses a (9)MR-142A Ignitor II.
    Everything should be here Thursday, I'll report back when I see how it fits.
    We will try to start it Saturday.
     
  10. tomnj

    tomnj Old fogie stogie

    Location:
    Scotch Plains, NJ
    Curious if the car will run better with the petronix. I have one laying around that I think is for an X1/9, but may work for my 850. Will have to check closer.
     
    Last edited: Jun 18, 2019
  11. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    I've only driven this one once and that was before I bought it. I hope it runs better than it did then, but ignition wasn't it's only problem.
     
  12. tomnj

    tomnj Old fogie stogie

    Location:
    Scotch Plains, NJ
    Normally ignition upgrades don't make a huge difference, but if nothing else, it may improve starting and idle. With only 53 HP, every little bit helps.
     
    NM850 likes this.
  13. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    This will be my first street 850 with a 903. All of the others were 843s and 817s.
    My only other 903 was a '70 H Production racecar that I autocrossed.
     
  14. myredracer

    myredracer True Classic

    I have an A112 Marelli electronic ignition setup for my 1050cc, 903-based motor. Also another Marelli setup for my OHV 1608cc 1438-based motor. Both distributors are new and the coil modules are used. Not cheap stuff. Has been in boxes for quite some time waiting to go into the motors (getting closer). I have no idea how much better these will be but not having to deal with points will be nice.

    Several decades ago I installed a generic capacitor discharge ignition in an 850. Ran a lot better and rev-ed higher. Do people still use CD ignitions?
     
  15. Yes. MSD makes quite a few.
     
  16. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    We have a MSD 6AL in our Supervee autocrosser. It's about 25? years old. I bought 2 of them when I had the 250GTE, but didn't use them on it.
    The one in the Vee has been running since the late '90s in rain, heat and whatever. It's always stored outside in the car covered wih a tarp. The only problem we had was from low battery voltage. Doesn't like that.
    The other one went in the 600 for both the 903 and the 1300/128. No problems there, big battery and better starters kept battery voltage up.
    I looked at putting the 600 unit in the 850 but at the moment we are going with the Pertronix.
     
  17. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    It's alive...
    After 10 years of sitting we started it today.
    New battery, Pertronix ignition, carb built from selected parts, new coil, new fuel pump, and a little wiring clean up.
    Waiting on gear drive starter, possibly needs some charging system maintenance.
    20190709_173230.jpg
     
  18. Rod Midkiff

    Rod Midkiff True Classic

    Location:
    Eugene, OR
    very cool!!
     
  19. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    Thanks.
    I thought the engine was junk because it ran (when it ran) really rough. Wouldn't idle or rev.
    We built a 21/23 I had in the junk carb bin, cleaned a bunch of parts and stuck it all together. We cleaned and rebuilt the entire fuel system.
    Now, with the cobbled carb, Pertronix installed and the timing set by ear you can start it, it will sit there and idle smoothly.
    Once it's warmed up you can start it just by turning the key. It acts like it's injected.
    It's an amazing change from what we had and I'm really happy I don't have to go into the engine right away.
     
    JimD likes this.
  20. khnitz

    khnitz Low Mileage

    Great job! Mine is a '73 in the same color. Other projects have priority at the moment, but I hope to get ours running this Winter.
     

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