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  1. #1
    Non-member gtmatt's Avatar
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    very rich on.idle

    D Well Got it running after 4 year project now she Starts ,but lumpy on idle very rich black smoke ,Everything iS new ,i took plugs out very black ,on idle if u use choke it cuts out and if u DAB the throttle it cuts out ,carb has also been rebuilt about 2 years ago Any clues Team Thanks matt

  2. #2
    Non-member Mart's Avatar
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    Re: very rich on.idle

    Could be fuel or spark related.

    Fuel...

    Stating the obvious first: Mixture screw ok, and adjusted correctly?

    If ok, remove the carb elbow, start the engine, and see if any fuel is dripping (or pouring) out of the aux venturi feed onto the throttle plate - If so, check the needle valve is sealing, the float pivot moves freely, the float itself isn't leaking, and check the diaphragms in the enrichment block.

    Spark...

    Check the rotor arm is lined up correctly (at TDC the rotor arm contacts should point at No.1 dizzy cap contact (nearest the radiator). If it's slightly off, the timing will be out thus so, hence will be 'firing' at the wrong point (cue weak spark).

    If all ok there, remove a sparkplug, stick an HT lead on, hold the tip near to an earth point, and crank the engine - Should see a fairly rapid succession of good, strong sparks. Check the other 3 HT leads in the same way. If poor/no spark, it's probably a naff HT lead, or the coil could be on the way out.

  3. #3
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Thanks mart will Check those

  4. #4
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Checked carb ok
    Checked plugs leads
    Checked spark
    Checked rotor arm at tdc see pic


    Took all plugs out and cleaned them it started ran sweet then 2secs later black smoke and horrible idle ???

    Any other ideas ?? Thanks matt

  5. #5
    Non-member GTphil's Avatar
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    Re: very rich on.idle

    Sounds a strange one mate, I'm presuming your running a standard fpr?? How's your fuel pressure?

    how many times have you cleaned the idle jet out?

    honestly pal, everytime I have my carb apart I have to clean, the idle jet out LOADS of times before it idles right. Might be worth a try, make sure you pull the jet apart and give it a good clean with carb cleaner.

    They block up really easily if all your boost hoses are new and the cooler any stray bits of silicone will end up blocking the idle jet for sure

  6. #6
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Not checked fuel pressure Its ,black smoke and plugs soot up easy ,can the Main Jet efffect idle ? Or running rich on idle ??

    Does the rotor arm look ok at tdc?

    I will Check for carb Air leaks tomoz with wd40

    Will vac lines or breathers make it run rich.

    The idle iS poor due to running rich i think ??

  7. #7
    Non-member Brigsy's Avatar
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    Re: very rich on.idle

    Is fuel dripping down the venturi when running?

  8. #8
    Non-member GTphil's Avatar
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    Re: very rich on.idle

    I get the same symptoms with the idle jet, I get black smoke and poor idle that dies as soon as I touch the gas pedal. The afr gauge reads off the scale lean. Very similar symptoms to an air leak.

    Do you have an afr gauge?

  9. #9
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Quote Originally Posted by Brigsy View Post
    Is fuel dripping down the venturi when running?
    No mate

  10. #10
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Quote Originally Posted by GTphil View Post
    I get the same symptoms with the idle jet, I get black smoke and poor idle that dies as soon as I touch the gas pedal. The afr gauge reads off the scale lean. Very similar symptoms to an air leak.

    Do you have an afr gauge?
    Got an afr not Got Power to it yet ,Got an aem one

  11. #11
    Non-member Brigsy's Avatar
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    Re: very rich on.idle

    Get your wideband hooked up. Play about with the mixture screw, iirc its clockwise to lean it off

  12. #12
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Well one still the same

    Got aem up and running it either reads of the scale or 17. ..?....???

    It will idle at 1000rpm anything under it will just cut out , if I press the throttle it pops and bangs ,with black smoke.

    ???

    Going to do a compression test tomorrow any other ideas thanks matt

  13. #13
    Non-member Brigsy's Avatar
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    Re: very rich on.idle

    Sounds very lean? Check for air leaks? Might be worth checking the dizzy drive isnt out?

  14. #14
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Quote Originally Posted by Brigsy View Post
    Sounds very lean? Check for air leaks? Might be worth checking the dizzy drive isnt out?
    Thanks mate how do I check for the dizzy drive out ?..

  15. #15
    Non-member Mart's Avatar
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    Re: very rich on.idle

    If that's TDC, that doesn't look like it's pointing at number 1 to me...

  16. #16
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Quote Originally Posted by Mart View Post
    If that's TDC, that doesn't look like it's pointing at number 1 to me...
    I will spin the drive gear 180 and see what happens

  17. #17
    Non-member Mart's Avatar
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    Re: very rich on.idle

    It's in the right area, but looks several degrees out.

    Has the dizzy gear been out/re-fitted?

  18. #18
    Committee Member chris's Avatar
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    Re: very rich on.idle

    I agree with mart i think your out with dizzy drive by abit i am sure mine was almost pointing at rad but can check for you tomoz

  19. #19
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Quote Originally Posted by Mart View Post
    It's in the right area, but looks several degrees out.

    Has the dizzy gear been out/re-fitted?
    Indeed it has been out and refitted ,how would I fit it correctly ?. Thanks matt

  20. #20
    Non-member Mart's Avatar
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    Re: very rich on.idle

    If you followed the guide in the Haynes manual, the 90deg' dizzy drive gear spiel is wrong - I've mentioned it several times over the years, so have a search to save me typing it out again

    Seeing as it's already fitted though, remove dizzy assembly and pull the drive gear out, noting the position of the 2 locating grooves before-hand, then simply pop it back in albeit rotated v slightly & dropped in at the next tooth, so to speak. You may need to trial & error it several times, before it's lined up correctly; ie, so that the arm does point to No.1

    If you cba to reseat the drive gear, cut the lugs off the base of the drive, rotate the whole unit until the rotor arm points to the correct position (use the cap for reference), then fit the clamp & securing bolt.

  21. #21
    Non-member Brigsy's Avatar
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    Re: very rich on.idle

    I had to make my dizzy adjustable on mine, the drive was never in the right place. Can only be down to my cam timing throwing it out.

  22. #22
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Well got it idling Perfect at 950'and below sounds perfect on idle afr 14.1 on aem starts first time every time .

    So now problem I have got is it will not rev above 2000rpm ,sounds like a misfire pops bangs , now if I let it idle it just spot on ?


    Any ideas thanks matt

  23. #23
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Quote Originally Posted by gtmatt View Post
    Well got it idling Perfect at 950'and below sounds perfect on idle afr 14.1 on aem starts first time every time .

    So now problem I have got is it will not rev above 2000rpm ,sounds like a misfire pops bangs , now if I let it idle it just spot on ?


    Any ideas thanks matt
    Could it ne timing

  24. #24
    Non-member GTphil's Avatar
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    Re: very rich on.idle

    popping and banging sounds like timing mate

  25. #25
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Quote Originally Posted by GTphil View Post
    popping and banging sounds like timing mate
    How do i time it up correctly ,tried Dizzy drive loads nd tdc ,cant get it right

  26. #26
    Non-member GTphil's Avatar
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    Re: very rich on.idle

    Not sure mate, it's not something I have ever experienced, I followed the Haynes when I built my lump and it was fine

    can only suggest what mart says above and make the drive gear adjustable and take it from there.

  27. #27
    Non-member Brigsy's Avatar
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    Re: very rich on.idle

    Dizzy drive is out mate. Turn the dizzy 180 deg and make it adjustable. You will need to swap the leads around too.

  28. #28
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Can Any one tell me step n'y step how to set Dizzy 180 out Im à bit useless
    Got it at tdc now and how it stands



    Thanks matt

  29. #29
    Committee, Shop Manager, SE Regional Rep Bigfoot's Avatar
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    Re: very rich on.idle

    If you want to turn the dizzy 180, you need to remove the dizzy itself, then inside that whole you will see the cogs, this needs to be turned around, I used a wooden stick and pushed it into the whole in the cog and lifted it up and turned it 180, then put back together.

  30. #30
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Quote Originally Posted by Bigfoot View Post
    If you want to turn the dizzy 180, you need to remove the dizzy itself, then inside that whole you will see the cogs, this needs to be turned around, I used a wooden stick and pushed it into the whole in the cog and lifted it up and turned it 180, then put back together.
    What about ht leads and then ajusting timing

  31. #31
    Committee, Shop Manager, SE Regional Rep Bigfoot's Avatar
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    Re: very rich on.idle

    If you are 180 degrees out, you can either swap the leads around or turn the cog around, dont do both. not sure how you can make it adjustable though

  32. #32
    Non-member Matt@CodeRedMotorsports's Avatar
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    Re: very rich on.idle

    Best way to check is....
    Get cyl number 1 on tdc. (Remember old renaults mean cyl 1 is nearest the flywheel, so cylinder 4 in English money).
    Take the dizzy out and check the gear is in the right position.
    Like this.....
    Attached Images Attached Images  

  33. #33
    Non-member Matt@CodeRedMotorsports's Avatar
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    Re: very rich on.idle

    .... As for adjusting the timing, in standard form you can't, apart from turning the gear one tooth and tweaking the dizzy, as ages ago I did make them slightly adjustable for Oli Davies, Dave Clark and myself at one point by skimming off the retaining section so you could swing the dizzy slightly.
    Same as the group a r11 setup.

    In fact I still have a couple of these 'adjustable' dizzys laying around in a box somewhere with new caps on.....

  34. #34
    Non-member Brigsy's Avatar
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    Re: very rich on.idle

    Matt, just undo the dizzy clamp and bolt, turn the body around 180. The hole that the bolt goes through will be on the opposite side. The clamp will then hold the dizzy in place. Your dizzy is now adjustable. No need to remove it fully.

    By looking at the pic it looks one tooth out? It should be straight at tdc?

    If you are using a right angled cap you will need to chop the lug off the dizzy. Its only a ten min job mate. Give me a bell and i will run through it on the phone.

  35. #35
    Non-member Mart's Avatar
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    Re: very rich on.idle

    #invisible

  36. #36
    Non-member gtmatt's Avatar
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    Re: very rich on.idle

    Well guys it was Dizzy Thanks for rtoc support , now for Little jobs for national day i hope

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