Any feedback on ignition timing adjustment? | FerrariChat

Any feedback on ignition timing adjustment?

Discussion in '365 GT4 2+2/400/412' started by raemin, Feb 20, 2021.

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  1. raemin

    raemin Formula 3

    Jan 16, 2007
    1,825
    Lyon (FR)
    Full Name:
    R. Emin
    Have you guys attempted to adjust the ignition timing of our cars?

    The reason I ask, is because my mechanic just told me it would make sense to adjust the ignition timing in order to match 1) new types of gasoline 2) my custom inlet timing. Based on his remark I've read the 4 manuals and the timing has varied quite a lot from since the 365:

    365 : 10° idle / 34° 6800rpm
    400Gt: 11° / 30° 5000rpm
    400i : 8° / 30° 5000rpm
    412 : 8° / 33° 5000rpm

    I am tempted to tilt the distributor by 3°, but there is no knock sensor on our cars...
     
  2. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,591
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    I would stick with the spec, but be sure your advance is working correctly! Many distributors lose their lubrication and corrosion sets in. I have experience! "Modern" fuel will mostly affect your fuel mixture. If you have a FI car, adjust your CO to spec.
    Ken
     
  3. markcF355

    markcF355 F1 Rookie
    Rossa Subscribed

    Jun 6, 2004
    3,493
    Schmeckelstan
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    Mark
    With the fly weight mechanism controlling the advance, I'm not sure those aren't effectively the same. . .

    Good point Ken. The seal at the bottom of the distributor shaft needs to be changed anytime you have the distributor out. It stops the engine steam from killing the advance mechanism.
     
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  4. raemin

    raemin Formula 3

    Jan 16, 2007
    1,825
    Lyon (FR)
    Full Name:
    R. Emin
    I am not chasing HPs... With delayed timing more heat escapes from the chamber to the fragile exhaust port.

    I presume the distributor is slightly out of spec now, so will focus on the 5000rpm timing and will settle for whatever timing between 30° and 33° generates the least amount of heat on the exhaust port. From then on if idle timing is grossly out of spec I'll have to see what are my options...

    Thanks for the distributor seal advice. I'll check the seal while the head is out. That's one more item to worry about, but reaching this distributor is such a pain that I'd rather do it while it sits on the bench.
     
  5. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,591
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    I had my distributor fully rebuilt by Dave North last year. I can put anyone in touch with him. He now has an ad in Prancer, FCA magazine.
    Ken
     
  6. GT4SBLUE

    GT4SBLUE Rookie

    Jan 4, 2017
    6
    UK
    Full Name:
    CHRIS JOHN PALING
     
  7. GT4SBLUE

    GT4SBLUE Rookie

    Jan 4, 2017
    6
    UK
    Full Name:
    CHRIS JOHN PALING
    I have just carried out engine set up on my 400I Auto
    My views are you set ignition to the fuel used, in the uk 97 is the most common higher octane petrol so set up for that.
    As lower octane fuel burns faster, I retarded the static timing from 8 advanced to 6 and reset the mixture which gave a better and lower speed idle I now idle at 850 to 900 rpm warm and as low as 650 rpm cold off choke without engine issue and with no gear selection jumping my fuel consumption has not changed by a measurable amount and temperature has not changed.
    Hope this helps.
     
  8. raemin

    raemin Formula 3

    Jan 16, 2007
    1,825
    Lyon (FR)
    Full Name:
    R. Emin
    Dave north has a nice website : https://www.marellidistributorservice.com/

    This being said I've chosen another route and added an old-tech tool to my garage :


    Still working after 60 years! Mark Saunders is sending me an adapters for the magneti marelli distributors (plus new caps and belts).

    Can't wait to see the 12 lights on the dial!
     
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  9. raemin

    raemin Formula 3

    Jan 16, 2007
    1,825
    Lyon (FR)
    Full Name:
    R. Emin
    That's a really cool machine, and it is "localised" (it's a 220v unit from the factory and all the texts are painted in French). The bad news is Mark does not have Magneti Marelli adaptor in stock, so will have to wait two months. I would have rather preferred to test the distributor before putting it back in the engine but will make it do.

    Once all is operational I I will test both my 400i distributor and the one form the 365 and will report!

    French texts
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    Nice picture with the afore mentioned adapter (my tester is not as shiny...)
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  10. samsaprunoff

    samsaprunoff F1 Rookie
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    Jun 8, 2004
    4,160
    Edmonton, AB Canada
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    Sam Saprunoff
    #10 samsaprunoff, Mar 4, 2021
    Last edited: Mar 4, 2021
    Good day Raemin,

    I have the same distributor tester! These are great units and work really well. Mine is in near mint original condition, as I was fortunate to find one locally that was once used in a Government vehicle service garage. Mine also came with the mobile base too. However, I think my original capacitors need replacing as well as the flash tube, as the strobe is not as bright as it should be. In case you do not have it, below is a link to the original operator manual of these devices that might be of interest:

    http://www.starchak.ca/tech/pdfs/sun manual.pdf

    There is/was a firm that specialized in replacement parts for these testers. The site is located here:

    http://paramountd.com/parts.html

    I checked the site now and it times out and so I am unsure if this is a website or network issue. The place also sells the marelli adapters and so you could check with them in case you did not wish to wait. Alternatively you can easily make an adapter with some Aluminum and an lathe. I designed up an adapter for my BB and it did not take my machinist long to make it.

    Also, you may need to get an ignition trigger adapter as well. These 504 machines are expecting to be triggered by points and not electronic pickups. As a result an adapter/converter will be needed. I will have to dig out mine, but I think I just used an old GM electronic module (< $10) and it worked like a charm.

    Lastly, take good care of your tester, as they are very desireable and so prices have been increasing steadily. Restored and high quality units can fetch over $2K, as many are used as ornaments in man-caves, etc.

    Cheers,

    Sam

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  11. samsaprunoff

    samsaprunoff F1 Rookie
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    Jun 8, 2004
    4,160
    Edmonton, AB Canada
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    Sam Saprunoff
    Good day All,

    Just an update to this thread... I recently had to check the advance curve on my boxer and so I brought out my Sun 504. My last use was some time ago and so I did not document how I wired up a GM HEI module to act as a signal conditioner between the BB's electronic pickup sensor and the 504's trigger circuit. The 504 was designed for breaker points and so the electronic pickup will simply not work. Although you can find vintage signal conditioners, which are sometimes called "amplifiers", it is easy and inexpensive to use a GM HEI module... that are plentiful and can be found anywhere.

    The 504's circuitry dates back to the 1950's / 1960's and uses tubes ... one for creating the high voltage for the Flash and another for the actual flashtube (Xenon). I won't bore you with the tech details, but the 504's trigger circuit is pretty basic, but does dump a lot of (DC) current through the trigger (breaker point)... around 1.8Amps or so. The electronic pickup sensor can sink very little current and has a small amplitude AC signal and so a converter or signal conditioner is required. Although a dedicated circuit could be designed, why bother when a GM HEI module could do the same thing? All that is needed is a HEI module, a +12VDC power supply (min 2A output), and some hook-up wire. Attached is a wiring diagram for my setup and it works perfectly. Hopefully my comments and the document saves others some time.

    Cheers,

    Sam

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