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Thread: mk3 1.4i single point, timing...

  
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    clarkey1984's Avatar
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    mk3 1.4i single point, timing...

    My little mk3 aint exactly what you would call 'fast' so i had a bit of a tinker...

    When i had my 1.4 nova a few years back, i advanced the ignition timing by loosening the 13mm nut and turning the dizzy cap clockwise a little bit, not far, maybe 3 or 4mm further round than standard, and the result was a bit more pull through the gears, perfecto.

    Now, my mk3 astra has the same engine, and from what i can see the same distributor system as the nova did, except the nova was carbed and this is single point injection, however, when i move the timing on this, even if its literally 1mm off where it should be, its faster, but all it does is pink as well.

    Im aware that pinking is caused by over advanced timing or a weak mixture, but it didnt do this on my other car with the same engine and dizzy when i moved it 3 or 4 times further, so why does it happen with this, is it that the injection system is set quite 'lean' as standard and any advancing will make it overly lean and therefore be the cause?

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    stevej66's Avatar
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    it is a different set up and ecu system thatn your nova and all you will do is causing excessive pinking from an over advanced ignition that will eventually destroy the engine. the single point injection unit is an unforgiving set up that has fuel delivery limitations

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    clarkey1984's Avatar
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    Ahh, that'll be why then, i have put it back to where it was originally anyway.

    Im not that clued up on all this injection malarky, so excuse me if this is a silly question, but if there are fuel delivery limitations with the SPI, could i just get a manifold and carb from an older 1.4 vaux and just bolt it on and it would run?

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    Noxious89123's Avatar
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    You could try running it on a higher octane fuel, that should help with pinking.

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    yes you could carb it but it most likely would fail the mot as the carb would not get near the emission level required for your year of vehicle. the alternative would be to convert yours to multi point injection, but it is quite involved

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    wayne67's Avatar
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    can i just ask have you ever had to replace the cam belt mine snapped i have a 1.4 astra i have refitted a new belt and water pump. the car is now starting but is running lumpy. i am pulling my hair out on what it could be please can anyone hel.

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    mikeysvauxshack's Avatar
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    The base ignition timing on the 1.4i is controlled by the ecu, the distributor doesn't really do much other than send the spark to the right plug.

    If you want to fit the MPi system, ideally you want the cylinder head it's bolted to aswell, because the inlet ports are round on the MPi, on the SPi they're square. It'll all still fit without the right head, but the mis-match in port shape wont help it run smoothly. To be honest it'll be easier and quicker to throw the whole MPi engine in.


    Quote Originally Posted by wayne67 View Post
    can i just ask have you ever had to replace the cam belt mine snapped i have a 1.4 astra i have refitted a new belt and water pump. the car is now starting but is running lumpy. i am pulling my hair out on what it could be please can anyone hel.
    If the timing marks are all lined up correctly, whip the cam cover off to check the followers, if they're ok you've probably got a few bent valves.

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    /\The distributor sets the static ignition timing, by where it is in relation to the cam.
    The ecu then adjusts the timing from this point.

    Moving the dizzy will have an effect on the ignition timing, to a certain extent.
    I know this first hand from spi engines ive had in the past.

    But agreed, they are not like old mechanical advance/retard dizzys fitted to carb engines.

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