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Rebuilding the 308 electronic ignition (SM805A distributor, Marelli AEI200 Ignition)

Discussion in '308/328' started by alhbln, Jan 24, 2014.

  1. magaoidh

    magaoidh Karting

    May 12, 2009
    220
    Ps I could feel the magnetic field on the 8 points in 360 deg.
     
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  3. magaoidh

    magaoidh Karting

    May 12, 2009
    220
    Pps MY dwell meter has a dual scale,where to read my Alfa spider four cyl.engine with EI,double the figure eg 26deg.is really 52 deg.
    If I use the same principle with the 308 engine then one bank reads 16 but is actually 32 deg.Combine the two banks and it is 64 deg.Is that logical?
     
  4. nerodino

    nerodino Formula 3
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    May 19, 2005
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    Graham
    If you go onto e bay motorpartsworld have the BERU modules for a bargain £17.48 with free p&p to the uk.....just ordered me a spare
     
  5. alhbln

    alhbln Formula 3
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    Mar 4, 2008
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    Hmm, 52 deg would be ok, not sure how read your dwell meter. At least the reading should only cater for one four cylinder bank. Just checked my notes, when setting up Grahams distributor with the Beru module on the distributor tester, i got 54º dwell on the built in dwell meter on the Sun tester, which seems to be correct.
    If you can feel the magnetic field resistance then the sensor distance and dwell should be fine though.

    Good info, thanks for posting!
     
  6. Andy 308GTB

    Andy 308GTB F1 Rookie
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    Jun 2, 2004
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    VR Sensors
    Whilst trawling the internet I found a potentially cheaper source for these.
    I thought I would stick it on this thread as it's pretty much the bible for this dizzy.

    Superformance
    Distributor Impulse Unit 30817065 £76.95

    Eurospares
    BOBINETTA COMPLETA DI FILO E SQUADRETTA 95300027 £55.00

    AutoRicambi
    Magnetic Pick Up Coil in Distributors & Components
    Magnetic Pick Up Coil Price: $30.90 (i.e. £18.20)

    Even with shipping to the UK that has got to be a good saving?
     
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  8. Ics19

    Ics19 Rookie

    Sep 8, 2019
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    Richard
    Great rebuild post, just what I needed :) Does anyone know the primary/secondary resistance specs for the Bosch 0 221 122 334 coil? Just wondered how close they are to the BAE 207A. Many thanks.
     
  9. alhbln

    alhbln Formula 3
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    BAE207A primary 1.4Ω, secondary 8KΩ (average max current before saturation 6A)
    Bosch 0 221 122 334 primary 0.8Ω, secondary 10KΩ (average max current before saturation 8A).

    In an electronic transistor ignition (e.g. with current control) you can easily use a Bosch 0 221 122 334 coil as replacement for a BAE207A.
     
  10. Ics19

    Ics19 Rookie

    Sep 8, 2019
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    Richard
    I guess those values are meant to be the other way around, unless the BAE 207A values in the first post are mis-typed? :confused:

    So the different primary:secondary ratio isn't detrimental to the resultant spark?
     
  11. alhbln

    alhbln Formula 3
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    Thanks for spotting this, you are correct as the BAE 207A is pri 0.8Ω. The difference between the secondary resistance for both coils does not make much of a difference, but the winding ratio, which is about 1:70 or the BAE207A and 1:85 for the Bosch. This will give a slightly higher output voltage with the Bosch.
     
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  13. Ics19

    Ics19 Rookie

    Sep 8, 2019
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    Richard
    Most helpful - thanks for the prompt reply and clarification. The Bosch is looking favourable and seemingly more available, although there appears to be a MAKO / Marelli production of the BAE207A (a MK1?) - does anyone know if this is the same original spec and reliability?
     
  14. Foxie

    Foxie Karting

    Oct 9, 2011
    65
    Wexford, Ireland
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    Sean Murray
    I have removed the SM 805A distributor on my 1978 308GTS just as I am fiinishing a full engine rebuild.

    I saw that the springs in the weights appear to be shot, and there are loose pins. I have ordered a distributor rebuild kit from Superperformance.

    I now see that this kit (from Hill Engineering ? ) is for the S159B distributor.

    Is this the same kit for the SM 805A ?
     
  15. alhbln

    alhbln Formula 3
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    I would think that the internals are different between the two dists. In general those rebuild kits are not plug&play, but require a distributor test stand (and the knowledge how to use it) to adapt the springs and washers to create the correct advance curve via the weights mechanism. Start with disassembling the SM805A and put the washers and springs in separate boxes based on where they came from. The springs are all different, as are the washers (thickness), so if you mix them up you end up with a different advance curve. Then compare the spring length and spring rate with the new kit you bought to check for compatability.
     
  16. Foxie

    Foxie Karting

    Oct 9, 2011
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    Sean Murray
    Thanks for that.

    The pictures of the new kit on the Superperformance website look identical.

    My first problem was how to dismantle the distributor, I couldn't find any info. I thought I might have to pull off the reluctor ring, but once I removed the circlip it came apart easily.

    I identified all the springs, pins, and barrells and their positions. I measured each item, see pic. The pins and barrels were more or less identical, and they are free to slide.
    The advance weights were identical, withthe inner drilling 10mm and the outer 15mm.
    The springs were of different lengths, the two short ones were the same length and coil turns, the longer ones had different lengths and coil turns.
    There was a red paint dot on the reluctor cross arm that I couldn't see for what purpose.
    There is also a red dot recessed into the rotor which would indicate which one of two ways it is assembled on the shaft.

    I didn't see any obvious wear or damage (there are 50K miles on the car and it seemed to be running ok before i dropped the valves )
    So I am looking forward to getting the new kit and comparing how they match.
     

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  17. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    I dont see any excessive wear on the parts from looking on your pictures. I would recommend to stay with the original setup unless you have access to a machine for adjustment of springs and shims. Clean and lubricate with some sticky grease and assemble as per original setup and then check for correct advance. It is in practical sense not possible to renovate the system without the right advance test machine available. I ended up converting all my f-cars from mechanical to digital advance for the same reason but that’s another story.

    Best, Peter
     
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  18. Foxie

    Foxie Karting

    Oct 9, 2011
    65
    Wexford, Ireland
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    Sean Murray
    Hi Pete,

    That's good to hear.

    I'll see how it goes.

    As Superformance advise that the BSM kit is no longer available, I would be looking for something like the digital system I fitted to my 1970 Lotus Elan +2S from 123Ignition in Holland.

    :)
     
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  19. alhbln

    alhbln Formula 3
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    Looks good, also what Peter said. Check the axles carrying the weights, this is usally where the wear starts, also the inside of the drums where the pins connect.
     
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  20. Foxie

    Foxie Karting

    Oct 9, 2011
    65
    Wexford, Ireland
    Full Name:
    Sean Murray
    I ordered to rebuild kit for the159B distributor from Superperformance, and it is exactly the same as the original one in my SM 805A, which has induction coils instead of points.

    However the pins and spring lengths are different.

    The old set had 3 different lengths of pins and springs. See pic. The new set has just 2 lengths of pins and 3 lengths of springs. 2 long pins 21.6mm, 2 short 19.5mm. 2 long springs 18.5mm, 1 short 15mm, 1 short 12mm.

    So it would seem that there is a difference in the advance curves, which I could check out once I get the engine running again.

    There was quite an amount of thick brown grease in the weights bowl, which I cleaned out. I haven't been able to find any information on lubricating the distributor, so I wonder what type of grease, how much, and how often ?

    Image Unavailable, Please Login
     
  21. 308inTex

    308inTex Rookie

    Dec 14, 2021
    7
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    Daniel Presser
    Was just referred to this thread and to my surprise people are still asking Q's & you are still responding! Wow.

    PERFECT description of symptoms on my carb 308 (front bank strong spark; rear bank weak spark). Car which I've owned since mid-80's has been in storage, so will have to go thru carefully.

    Your thought on this (which has scared me):

    With original coil wire weak rear bank spark.
    Tried with known good coil wire on that bank --- engine started to turn then locked up as if a mechanical interference issue (gasp), starter solenoid clicking. Went back to OEM coil wire and engine turned over just fine but, again, weak spark & difficult to start.

    Maybe just low battery .... but any words of wisdom such as "STOP! Go NO FURTHER ..."?
    Can't imagine why the engine would simply lock up with 1 coil wire but be OK with a different coil wire.
     
  22. alhbln

    alhbln Formula 3
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    Weak spark could have various reasons, It would be a good start to change coil, ignition module and wiring between the banks to see if this makes a difference and helps pinpointing the broken component.
    Engine locking up as described does not sound so healthy. With a car taken from storage i would remove the plugs and put a bit of oil into the cylinders and then try to manually turn the engine by turning the crankshaft pully with a wrench first to check out if there are any mechanical issues before starting the car.

    A broken carb flooding a cylinder with fuel can create a hydrolock where the piston(s) can't move anymore and locks up the engine. Would recommend to first remove all spark plugs and check that the cylinders have not been flooded with fuel before proceeding.

    Then proceed by checking the battery voltage while starting (should be 9V or better) and the ignition components. The difference in the coil wires might be between a solid copper wire and a resistance wire where the copper wire works better with a weak ignition, or even a damaged coil wire

    Good luck!
     
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  23. 308inTex

    308inTex Rookie

    Dec 14, 2021
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    Daniel Presser
    Sorry - I was unclear.

    The engine turns over and starts (albeit running poorly) with the OEM wire.
    Then, disconnecting that 1 OEM coil wire (rear back) on both ends and simply substituting in a good coil wire (not OEM) and the engine starts to turn then locks. Starter solenoid clicking away. Substituting the OEM coil wire back in & the engine starts/runs again.

    Weird! Maybe just bad battery and the load is too much for it when both banks are firing well? Will check voltage.
     
  24. thorn

    thorn F1 Rookie
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    Step one, always: check the battery.
     
  25. alhbln

    alhbln Formula 3
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    The battery should only be relevant for starting. When you are above 2000-2500 RPM the supply comes from the alternator and the battery only buffers it.
     
  26. 308inTex

    308inTex Rookie

    Dec 14, 2021
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    Daniel Presser
    THAT's curious (and makes sense!). Why in my case? Because the car starts very hard, then idles very rough, but after a minute or 2 when I can finally pulse the RPMs up to 2K or 3K it suddenly "clears" and gets power. Still not super, but it's a sudden, noticeable change. Will go back & check battery voltage when cranking.

    But would you mind checking what I've measured so far for me?

    Top coil/amplifier removed & sitting on side of engine. Measured:
    coil primary: 1.1 ohms
    coil secondary: 10.91 ohms
    voltage at coil + terminal (non running): 11.3v
    VR resistance: 0.781 ohms
    coil amps (non running but with starter engaged): 1.1 amps (0.1 w/o starter turning)
    Coil model: AEI200A (came with this used car when I bought it in 1985)

    Car always ran great prior to lengthy storage ... the 2 coil packs are NOT the same ... front bank (lower coil pack) strong spark; rear bank weak spark).

    I'll check battery voltage when starting; also try for a better amperage check (was using thin jumper cables for V+ and ground connections when I tested; maybe inhibiting current).

    Anything bad so far? Suggestion of what to check next?
     
  27. alhbln

    alhbln Formula 3
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    Coil secondary should be Kohms (Kiloohms), 10.91Kohm, good. 781 Ohm for the VR Pickup is also fine.
    Coil ampere when starting should be >3-4 Amperes but this requires at least an RMS capable current clamp meter.
    Also, current between both coils should be the same (max 20% variance maybe).

    The two coil packs have the same components but different spark output? Or also different components?
    If the components are identical then most probably the VR gap has not been properly set up for the weaker spark bank.
     
  28. derekw

    derekw Formula 3
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    Sep 7, 2010
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    Adrian, do you know what the tach signal is for these single distributor cars? I will be switching the the programmable MSD (using the two VR sensors in series worked ok at low Roma on the bench) and may need to halve the pulses with a simple circuit. Thanks Derek
     

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