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  1. #1
    Regional Rep Chris Hebden's Avatar
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    Leaning off boost part of the carb

    I would like some confirmation about leaning the off boost part of the carb. During the run in i havent got the turbo actuator attached so want to lean the carb. When i checked the carb i have a 1.3mm main and i 1.0mm ac.

    I have drilled out the AC to 1.2mm but i am still getting AFR's in the low 10's on acceleration. Would it be worth soldering the main up and drilling that down to a 1.2mm or change the AC to something smaller? What are peoples thoughts, cheers Chris

  2. #2
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Chris Hebden View Post
    I would like some confirmation about leaning the off boost part of the carb. During the run in i havent got the turbo actuator attached so want to lean the carb. When i checked the carb i have a 1.3mm main and i 1.0mm ac.

    I have drilled out the AC to 1.2mm but i am still getting AFR's in the low 10's on acceleration. Would it be worth soldering the main up and drilling that down to a 1.2mm or change the AC to something smaller? What are peoples thoughts, cheers Chris
    I think you should try a standard a/c 125.

  3. #3
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Thanks for the info buddy, i have only got 1.2 or 1.3mm drill bits, could i wiggle the 1.2mm to roughly the right size?

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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Chris Hebden View Post
    Thanks for the info buddy, i have only got 1.2 or 1.3mm drill bits, could i wiggle the 1.2mm to roughly the right size?
    I think 1.2 will be fine. Just give it a try,

  5. #5
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Thats what AC i am using now (1.2mm) and getting AFR's in the low 10's

  6. #6
    Non-member Mart's Avatar
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    Re: Leaning off boost part of the carb

    Defo drop the main to 1.2mm. That'll be where most of the richness is originating from.

    If the afr's are going mega rich when giving it gas, the acceleration pump jet might need adjusting.

  7. #7
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Is the accel pump always working Mart? Ok i'll drop the main down to 1.2mm and try and find the info on adjusting the accell pump.

  8. #8
    Non-member Mart's Avatar
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    Re: Leaning off boost part of the carb

    It is, everytime you move the gas pedal downwards.

  9. #9
    Non-member Mart's Avatar
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    Re: Leaning off boost part of the carb

    I posted a guide on adjusting the acc' pump lever/throw. Search '5mm drill bit' and that should bring up the thread.

  10. #10
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Cheers Mart, on it now

  11. #11
    Non-member Andrew Cooke's Avatar
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    Re: Leaning off boost part of the carb

    I'm trying to remember whether the 1st stage can come in? Do you still have the standard jet in there?

  12. #12
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Found it Mart https://www.rtoc.org/boards/showthrea...m+drill&page=2 cheers

    Andrew, i havent the foggiest if the 1st stage is standard or not. I havent dismantled that part of the carb, was hoping not to untill i get the on-boost fuelling sorted. Do you think its going to factor?

  13. #13
    Non-member Andrew Cooke's Avatar
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Chris Hebden View Post
    Found it Mart https://www.rtoc.org/boards/showthrea...m+drill&page=2 cheers

    Andrew, i havent the foggiest if the 1st stage is standard or not. I havent dismantled that part of the carb, was hoping not to untill i get the on-boost fuelling sorted. Do you think its going to factor?
    well, in the bad old days you fitted a 1.3 main, and swapped the air corrector for the first stage. That bigger first stage made things go very rich just as you were coming on boost. I'm not certain, but it's possible that you're working in that region. I'd take the side off to have a look.

  14. #14
    Non-member Brigsy's Avatar
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    Re: Leaning off boost part of the carb

    I decreased the 1st stg to .6 to lean the cruise/low boost afr's on my current setup. Adjusting the acc pump made little difference for me, just caused a flat spot on acceleration.

  15. #15
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Andrew Cooke View Post
    well, in the bad old days you fitted a 1.3 main, and swapped the air corrector for the first stage. That bigger first stage made things go very rich just as you were coming on boost. I'm not certain, but it's possible that you're working in that region. I'd take the side off to have a look.
    That would coincide with what the rr showed many moons ago! That on part throttle the afr would fall as low as 9's on one run! I'll have a look see tomorrow. Can you remember if this is boost effected?
    Last edited by Chris Hebden; 17-08-2009 at 23:53.

  16. #16
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Chris Hebden View Post
    Thats what AC i am using now (1.2mm) and getting AFR's in the low 10's
    Sorry I tought you are still using 1.0 a/c.

    Than try a smaller main and E0.
    There were some carbs where the E0 was 0.8 standard.

  17. #17
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Jimmy_GTT View Post
    Sorry I tought you are still using 1.0 a/c.

    Than try a smaller main and E0.
    There were some carbs where the E0 was 0.8 standard.
    Whats an E0 matey?

  18. #18
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Chris Hebden View Post
    Whats an E0 matey?
    The first stage. Maybe it is only 'E' not 'E0' it is just the circle behind.



    Sorry!

  19. #19
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Great pic, thanks! I'll have a look at the first stage once i reduce the main to a 1.2mm!

  20. #20
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Chris Hebden View Post
    Great pic, thanks! I'll have a look at the first stage once i reduce the main to a 1.2mm!
    Just the one from the 'All about the 32DIS Carburettor' article.
    http://www.gtturbo.org/boards/showthread.php?t=4734

  21. #21
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Well had a little play tonight! Good shout Andrew, i had a 1.2mm first stage so i reduced that to a 1.0mm, adjusted the accelerator arm as Marts description and soldered the main jet and reduced that down to 1.2mm. Now i have got good AFR's through out the range. 12.0-12.6 fluctuating.

    So my carb stands at the minute:

    1.2mm main
    1.0 1st stage
    1.1 2nd stage (bush)
    1.2 AC

    Going to wait till Sunday till i run any boost and we'll see what the AFR's are doing! Hopefully Markey will be able to sort the carb out from then on!

    How do people think this will stand up to taking boost? I'm thinking that the AC will need to be reduced slightly and maybe the enlarge the 2nd stage?? Any thoughts on this?

  22. #22
    Non-member Markey Mark (BD)'s Avatar
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    Re: Leaning off boost part of the carb

    What boost you wanting to run mate?

  23. #23
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Well i was hoping to run 18psi, but we'll see how many miles i rack up before Sunday. Around 16si would be good for now i think?

  24. #24
    Non-member Markey Mark (BD)'s Avatar
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    Re: Leaning off boost part of the carb

    May find we just need to take the 2nd stage out alittle more to run the boost but will see on sunday, we'll stick my LM-1 on it and have a play.

  25. #25
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Yea sounds great buddy! Will the 2nd stage bush be kept in place or do you think we'll have to drill and tap it?

  26. #26
    Non-member Markey Mark (BD)'s Avatar
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    Re: Leaning off boost part of the carb

    We can just drill it out but we'll do it stage by stage so we don't go too big. If we did we'll then have to drill it and tap it to bring the size down

  27. #27
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Sounds great Mark! Looking forward to using the car again!

  28. #28
    Non-member Andrew Cooke's Avatar
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    Re: Leaning off boost part of the carb

    it's still pretty rich for no boost, you don't need any more than 13.5, and part throttle cruise can be 14.7, or leaner.

  29. #29
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Andrew Cooke View Post
    it's still pretty rich for no boost, you don't need any more than 13.5, and part throttle cruise can be 14.7, or leaner.
    Part throttle is in the high 13's upto 15 in some instances. I didnt want to go too crazy on this part as it wont be long till i am running boost. Will adding boost change these parts of the carb? Should i be trying to get it leaner now?

  30. #30
    Non-member Andrew Cooke's Avatar
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    Re: Leaning off boost part of the carb

    since you're playing on the weekend I'd leave it in now, but bear it in mind when you're making changes, you might be able to kill 2 birds with 1 stone

  31. #31
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Andrew Cooke View Post
    but bear it in mind when you're making changes, you might be able to kill 2 birds with 1 stone
    AY???? I am always game for halving work load, what do you mean?

  32. #32
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    Re: Leaning off boost part of the carb

    Quote Originally Posted by Chris Hebden View Post
    Yea sounds great buddy! Will the 2nd stage bush be kept in place or do you think we'll have to drill and tap it?
    How can you tap the 2nd stage?
    I have one carb which has been drilled too much...

  33. #33
    Regional Rep Chris Hebden's Avatar
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    Re: Leaning off boost part of the carb

    Not too sure on the ins and outs of it but from what i understand you drill out the 2nd stage to a diameter that you can tap a thread that will accept the AC jet.

    Here is a thread about it https://www.rtoc.org/boards/showthrea...t=drilling+2nd

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