View Full Version : Leaning off boost part of the carb
Chris Hebden
17-08-2009, 21:53
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
Jimmy_GTT
17-08-2009, 22:05
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.
Chris Hebden
17-08-2009, 22:07
:crap: 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?
Jimmy_GTT
17-08-2009, 22:10
:crap: 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,
Chris Hebden
17-08-2009, 22:22
Thats what AC i am using now (1.2mm) and getting AFR's in the low 10's
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.
Chris Hebden
17-08-2009, 22:30
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.
It is, everytime you move the gas pedal downwards.
I posted a guide on adjusting the acc' pump lever/throw. Search '5mm drill bit' and that should bring up the thread.
Chris Hebden
17-08-2009, 22:41
Cheers Mart, on it now
Andrew Cooke
17-08-2009, 22:49
I'm trying to remember whether the 1st stage can come in? Do you still have the standard jet in there?
Chris Hebden
17-08-2009, 22:54
Found it Mart http://www.rtoc.org/boards/showthread.php?t=5229&highlight=5mm+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?
Andrew Cooke
17-08-2009, 22:59
Found it Mart http://www.rtoc.org/boards/showthread.php?t=5229&highlight=5mm+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.
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.
Chris Hebden
17-08-2009, 23:43
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?
Jimmy_GTT
18-08-2009, 07:55
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.
Chris Hebden
18-08-2009, 08:58
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?
Jimmy_GTT
18-08-2009, 09:09
Whats an E0 matey?
The first stage. Maybe it is only 'E' not 'E0' it is just the circle behind. ;)
http://old.rtoc.org/articles/i/autofolder/LEZDMZDJCNRIPDVIQDMK.jpg
Sorry!
Chris Hebden
18-08-2009, 09:11
Great pic, thanks! I'll have a look at the first stage once i reduce the main to a 1.2mm!
Jimmy_GTT
18-08-2009, 09:14
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
Chris Hebden
18-08-2009, 21:08
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?
Markey Mark (BD)
18-08-2009, 21:09
What boost you wanting to run mate?
Chris Hebden
18-08-2009, 21:15
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?
Markey Mark (BD)
18-08-2009, 21:17
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.
Chris Hebden
18-08-2009, 21:19
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?
Markey Mark (BD)
18-08-2009, 21:23
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
Chris Hebden
18-08-2009, 21:25
Sounds great Mark! Looking forward to using the car again!
Andrew Cooke
18-08-2009, 22:16
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.
Chris Hebden
18-08-2009, 22:27
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?
Andrew Cooke
18-08-2009, 22:35
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:)
Chris Hebden
18-08-2009, 22:39
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?
Jimmy_GTT
19-08-2009, 07:15
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...
Chris Hebden
19-08-2009, 08:44
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 http://www.rtoc.org/boards/showthread.php?t=8497&highlight=drilling+2nd
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