78 308 gts euro single dist. w/ electronic pickups | FerrariChat

78 308 gts euro single dist. w/ electronic pickups

Discussion in 'Technical Q&A' started by daddad, Dec 7, 2011.

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  1. daddad

    daddad Rookie

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    #1 daddad, Dec 7, 2011
    I have a euro model and is one of the few with single dist. and electronic pickups in dist. all factory. I lost insulation on one electronic pickups in dist.and shorted out on cylinders 5 thru 8. I ran car on 1 thru 4 a short distance. I replaced two new pickups in dist. and reinstalled dist. car started when set number one to tdc was backfiring thru exhaust. Then advanced dist. beyond timing marks with light backfiring stopped starts right up but won"t idle. I set dist and lower rotor contact to cylinder one compressing stroke. Where is my timing mark. Someone told me the timing belt cam on cylinders 5 thru 8 might have skipped a tooth. Are there tdc marks on cam sprockets. thanks
     
  2. BigTex

    BigTex Seven Time F1 World Champ
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    #2 BigTex, Dec 7, 2011
    Last edited: Dec 7, 2011
    No, the reference marks are on the cams themselves, behind the gears...the gears are adjustable.

    Belts do not normally 'skip one tooth" and then reseat themselves to run normally, they would shear a lot more than one off when they fail...something much simpler is amiss...
     
  3. daddad

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    #3 daddad, Dec 7, 2011
    if it is running and does not backfire while revving the timing has to be close? Flywheel timing tdc way advanced. Is there any type of advance to unhook while timing.I looked in dist. under electronic pick.ups it looked like a centrifical pin type of advance.Thanks for input.Is there any literature on setting ignition timing on 78 308 euro single dist. with electronic pickup coils.
     
  4. alhbln

    alhbln Formula 3
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    #4 alhbln, Dec 10, 2011
    Did you swap the two VR sensor wires by any chance? Doing so would change the timing by several degrees.
     
  5. daddad

    daddad Rookie

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    #5 daddad, Dec 26, 2011
    thanks i will give it a try
     
  6. Martin308GTB

    Martin308GTB F1 Rookie
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    #6 Martin308GTB, Dec 27, 2011
    Last edited by a moderator: Sep 7, 2017
    Let me add this hint.
    For a quick check of the timing without removal of the cam covers there is a special tool. Picture - sorry; scanned Stone Age Polaroid - shows the original Ferrari tool. Tool no. is handwritten on top of the pic.
    I think one could easily fabricate something like this.

    Best Regards from Germany

    Martin
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  7. daddad

    daddad Rookie

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    #7 daddad, Dec 30, 2011
    i tried swapping vr wires car would not run even when all 4 cams on mark and timming at tdc and low rotor contact pointing on number 1 in dist on compression stroke. Then swapped vr wires again and everything lined up at tdc and low rotor contact has to point at number 8 terminal in dist. to run. on dist top vr wire by number 1 on dist. goes to top coil and fires cylinders 1 thru 4 , bottom dist. vr wire goes to lower coil and fires cylinders 5 thru 8.
     
  8. alhbln

    alhbln Formula 3
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    #8 alhbln, Dec 30, 2011
    Ok, so the VR wiring seems to be not the culprit. I don't have first hand experience with the EU single dist configuration, but on the previous 308 model with a points setup a wiring defect/short with the emission control setup which retards the timing can lead to similar symptoms. Does your 308 have a emission control setup for retarding the timing? I don't think that the european 308's had this setup but if it does have one then that would be the next thing worth to look at.
     
  9. daddad

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    #9 daddad, Dec 30, 2011
    no emission at all on car ,took valve covers off and everything is right on the marks. ????????? I really appreciate the help.
     
  10. daddad

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    #10 daddad, Dec 31, 2011
    do you think maybe the advance in dist. is stuck. tomorrow i will pull dist. and check if it free.
     
  11. alhbln

    alhbln Formula 3
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    #11 alhbln, Jan 3, 2012
    Kind of, if the springset for the initial advance phase (idle to ~2000 RPM) is broken you can have similar effects. It's not very likely that the advance mechanism quits the job when you just exchange the pickups, might be a coincidence though.
    If you have access to a workshop with distributor tester i think it would be a good next step to check out the timing curve of the distributor to make sure the advance mechanism is good. If not, check out the springs and weights/weight axles by hand, many advance mechanism defects can be easily spotted that way.

    You posted that after the pickup exchange the 308 ran but backfired through the exhaust, which would indicate a too retarded ignition timing. Question, did that happen only when idling or also on higher revs?

    Then you advanced the static timing so the backfiring stopped but the 308 would not idle which could indicate a too advanced timing where the pressure is reached before the piston is at TDC so the engine slows down and then dies.

    happy new year!
    Adrian
     
  12. daddad

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    #12 daddad, Jan 4, 2012
    Happy New Year, Had a set back trying to set dist. pull off cap. to check location of rotor. left it connected to wires. Rotor caught inside cap and snaped off center of cap contact while turning engine by hand. Waiting for new cap from superformance they were the lowest price. And also found out Magneti-Marelli does not make that cap any more.Its is made by a german company. They have two caps listed one is electronic,other is a points.They sure look the same to me. Well while waiting for parts polished valve covers, front dist. blank plate and crank breather to valve cover plate. Also whoever worked on my car before used some black sealant from hell had a hard time cleaning gasket off it split the gasket in half,gasket ripped in half valvecover and head slow process on alumnium. What gasket cement works good on valvecovers and is still removable to adjust valves. Thanks
     
  13. alhbln

    alhbln Formula 3
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    #13 alhbln, Jan 5, 2012
    Sorry to hear that! The black sealant from hell sounds like it was window sealant. Not an expert on gaskets but new gaskets should not require any sealant?

    Can you tell us a bit more about how the engine ran in idle/driving, and how it ran after you advanced the dist?
     
  14. daddad

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    #14 daddad, Jan 5, 2012
    waiting on new cap.
     
  15. daddad

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    #15 daddad, Jan 9, 2012
    Still waiting on my dist. cap and rotor from superformance. I have a question on the electronic ignition i have a single dizzy with two vr pickups connecting to two gm hei ignition modules 4-pin type which is connected to 2-massive heatsinks with coils. now if i understand correct these hei modules are basic electronic triggers transmitting signals between vr pickups and coils. like pulling a trigger on gun. And i see there are racing and oem modules available is there a difference. and last question is after 34 years does the heatsink paste under these units lose there heat transfer capability and over heat causing problems.
     
  16. alhbln

    alhbln Formula 3
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    #16 alhbln, Jan 9, 2012
    HEI modules process the VR signal from the pickups, adjust the dwell, limit the coil current so it won't saturate/overheat and switch ground to the coil via a power transistor to charge the coil. The difference in HEI modules available on the market is in the ability to control dwell based on the RPM and the output current it can switch. Most HEI modules handle a coil current of 4-5 ampere.

    I had a range of these on the test bench and a cheap one for racing ("Extreme Output") was actually the lowest performing one, so it makes sense to spend a tad more and buy a known brand when you need to get new ones. Racing modules such as Pertronix Flamethrower "Race only" deliver 7 Ampere or more but require a compatible coil to do so, and they can overheat in lower RPMs where the dwell is higher (which doesn't matter in racing use where you stay with high RPMs most of the time), so a good street one would be the best choice.

    I've posted a bit more details about the 308 VR setup with HEI modules here (post#20):
    http://www.ferrarichat.com/forum/showthread.php?t=337638

    It is a good idea to replace the old heatsink paste (thermal grease or heatsink compound) if it has never been refreshed before, you can source a new one easily from electronic stores such as digikey. The standard white heatsink paste works great, no need to get an exotic one.
     
  17. daddad

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    #17 daddad, Jan 9, 2012
    I was looking at the Napa echlin distibutor control module ECHTP45 ,4-pin which is stock replacement for the gm that was in it. I was going to use a high performance module but its only good for racing and high rpm,s after reading your posts. Unless there is a better choice.Thanks for the info.
     
  18. daddad

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    #18 daddad, Jan 12, 2012
    Just received my new distributor cap it is wrong cap,single for points not electronic type. Is the only difference the two cut outs in base. thanks
     
  19. daddad

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    #19 daddad, Jan 12, 2012
    Last edited by a moderator: Sep 7, 2017
    Here are two caps the one with cutouts is original magnet marelli single dizzy electronic, second is the German replacement but for points with no cutouts. That's the only difference I can see.
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  20. alhbln

    alhbln Formula 3
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    #20 alhbln, Jan 12, 2012
    Thank you, i was missing that photo, added to my archive. The sensor cutouts should be the only difference from what i know.
     
  21. daddad

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    #21 daddad, Jan 16, 2012
    Last edited by a moderator: Sep 7, 2017
    When setting the timing, bring flywheel to the +6 mark by the pm1-4 mark, set distributor rotor to cylinder 1. I have been setting distributor cylinder 1 and flywheel mark at pm 1-4 which is tdc. Will this make a difference. In the pic it's running but stalls out. Thanks ken
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  22. daddad

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    #22 daddad, Jan 20, 2012
    Here are some more pics changing ignition modules did not use elect.grease that came with accel modules. I used heat sink compound.
     
  23. daddad

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    #23 daddad, Jan 20, 2012
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  24. alhbln

    alhbln Formula 3
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    #24 alhbln, Jan 23, 2012
    Looks good! Have you made progress regarding the timing setup, engine now running better?
     
  25. daddad

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    #25 daddad, Jan 24, 2012
    After changing Ignition Modules to Accel started right up,set timming at 6 BTDC no backfiring,advances nicely at high RPMs. Sounds Great, It seams when the insulation rotted off the VR pickups it shorted out the Ignition module, which messed up the timming. Can't thank you enough Adrain for the info. Now to change the Alternator its arking when running and water pump is locking up making belt squeal. Take care Ken
     

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