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tuning a 1.3 rallye engine with bike carbs

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  • tuning a 1.3 rallye engine with bike carbs

    I am working on an 1989 AX GT for track use in which I am planning to fit a 1.3 rallye engine. I am looking for information and ideas on how to get the most out of the engine.

    I will be using the corresponding 1.3 20cb90 gearbox which I have already rebuilt, new bearings, synchros and a quaife LSD. I also have a 180mm billet steel lightweight flywheel to go with it. Clutch still to decide.

    Now I am thinking about what to do to the engine?
    I am planning to use bike carbs (Danst engineering solution) with the ignition system of the old AX GT 1.4 mono point engine. (Dizzy). That will save me a lot of wiring and also no need for an ECU. It will keep things simple from that end (and cheaper to start with). However, I have all the 1.3 rallye wiring loom, inlet system and ECU, but I like the idea of bike carbs and improve the performance of the 1.3 engine.

    1) Will the dizzy of the 1.4 monopoint injection engine be suitable for the 1.3 engine with carbs? Will the advance ignition curve be okay and which carbs and manifold would suit the engine the best?

    2) What can I do to the engine and head to get more power out of the carbs?
    Flow the head to start with, different cam shaft (which one?), adjustable pulley, 4-2-1 manifold, remove the cat (allowed for cars this age in the Netherlands), anything else? Increase the compression, need for other pistons/conrods?

    3) As I am going to use the short ratio 1.3 gearbox in combination with 13 inch AX GTI 4 stud wheels instead of the standard 14 inch AX GT 3 stud wheels, I don't want to run against the maximum rpm to soon when in different gears and/or blow the engine.
    What can I do to increase the maximum rpm that the engine can handle?
    Balance the crank shaft?, use stiffer valve springs, anything else?

    Any ideas are welcome and what HP would be possible do you think?
    thanks,

    Michel

    The little cracker
    Last edited by micheldeman; 27-02-2020, 06:01 PM.

  • #2
    regrinding the crankshaft?

    Ok, I have dismantled my 1.3 engine and measured up the crankshaft. Journal 5 (counted from the flywheel side) of the main bearings shows signs of wear, also it measures a diameter of 49,995mm which is out of spec according to Haynes page 2C.3 (referring to the specs of the 1360 engine as specs for the 1.3 are not given).
    The others journals all measure 49,970mm, which is fine and all look good.
    All the big end journals measure 44,985 and all look fine too.
    Is it wise to regrind the main bearings and to what diameter? Also any advice on which and what size bearings to use is welcome. I am planning to run on higher revs.

    The other thing is that there's a groove on the flywheel side caused by the oil seal.

    Comment


    • #3
      that journal is LESS worn than the others, so I'm not sure why you would grind that crank!

      the seal on the crank does have a little wiggle room in its bore so if the wear is causing any issues you can get around it.

      Comment


      • #4
        Originally posted by welshpug View Post
        that journal is LESS worn than the others, so I'm not sure why you would grind that crank!
        Sorry, typo mistake, the diameter of that journal measures 49,955. So, is worn and out of spec.


        Bad side of this journal


        Good side of this journal (ignore the measurements written on the back ground)


        Groove left behind by the oil seal


        In detail
        Last edited by micheldeman; 27-02-2020, 05:59 PM.

        Comment


        • #5
          Chuck it all in the bin and buy my old 1.6 8v, everything you need to get it going with a reliable ~140bhp
          I love Throttle Bodies

          Originally posted by Lewis
          My resolution for 2011 is to sort my fucking car

          Comment


          • #6
            Originally posted by Gus View Post
            Chuck it all in the bin and buy my old 1.6 8v, everything you need to get it going with a reliable ~140bhp
            No,thank you

            Comment

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