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89shortbox
Joined: 04 Nov 2007
Posts: 153
Location: Michigan
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 Posted: Wed Sep 15, 2010 1:32 pm Post subject: 2 circuit idle |
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So Ive got (3) 2 circuit idle carbs layin around. I was looking at the path in the base plate that goes front to back that is supposed to feed the idle port in the rear. On all the 3 carbs the idle port in the rear isnt even drilled.
2 carbs are mech. sec. and 1 is vac. sec.
In all 3 carbs the rear t-slot is functional.
What is the reasoning behind the idle port being non-existent in the rear if there is a feed passage coming from the front.
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89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season. |
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Drag Chevette
Joined: 18 Sep 2007
Posts: 458
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| Posted: Wed Sep 15, 2010 10:03 pm Post subject: Re: 2 circuit idle |
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| 89shortbox wrote: | So Ive got (3) 2 circuit idle carbs layin around. I was looking at the path in the base plate that goes front to back that is supposed to feed the idle port in the rear. On all the 3 carbs the idle port in the rear isnt even drilled.
2 carbs are mech. sec. and 1 is vac. sec.
In all 3 carbs the rear t-slot is functional.
What is the reasoning behind the idle port being non-existent in the rear if there is a feed passage coming from the front. |
those carbs didnt come as four corner idle, the only idle air mix screws were on the primary blocks.
on four corner the ports need to be drilled and the paths need to be blocked.
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89shortbox
Joined: 04 Nov 2007
Posts: 153
Location: Michigan
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| Posted: Wed Sep 15, 2010 11:58 pm Post subject: |
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| Quote: | those carbs didnt come as four corner idle, the only idle air mix screws were on the primary blocks.
on four corner the ports need to be drilled and the paths need to be blocked. |
I understand.
But my point is the paths are there to feed idle air and fuel to the rear idle ports on 2 corner adjustable idle. But yet on 3 carbs the rear idle port is not drilled.
WHY?
_________________
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89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season. |
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Drag Chevette
Joined: 18 Sep 2007
Posts: 458
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| Posted: Fri Sep 17, 2010 11:09 pm Post subject: |
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| 89shortbox wrote: |
But my point is the paths are there to feed idle air and fuel to the rear idle ports on 2 corner adjustable idle. But yet on 3 carbs the rear idle port is not drilled.
WHY? |
Your thinking backwards....
they are not there to feed the rear, the fuel actually comes from the rear to the front.
they keep the fuel flowing through the idle circuit on the secondary blocks to keep fresh fuel available for the transition slots.
look at your secondary idle air bleeds, they will be smaller than the primary....this is done to aid in the fuel draw to the transfer.
without the channel pulling fuel the transition slot would act as an air bleed around the throttle blade, resulting in little or no fuel flow at idle around the transition slot..
the reason we plug the channel and drill the hole is to make the transition slot fuel more reactive to the related venturi.....and dont forget to change the idle air bleed.
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Drag Chevette
Joined: 18 Sep 2007
Posts: 458
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| Posted: Fri Sep 17, 2010 11:13 pm Post subject: |
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| this is part of the reason carb kits dont always work the way they should....they are generally four corner and in your type carb they throw the fuel curve off. |
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89shortbox
Joined: 04 Nov 2007
Posts: 153
Location: Michigan
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| Posted: Sat Sep 18, 2010 7:54 pm Post subject: |
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It cant feed any idle fuel cuz the idle mixture screw isnt drilled in the rear metering block.
_________________
----------------------
89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season. |
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Drag Chevette
Joined: 18 Sep 2007
Posts: 458
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| Posted: Mon Sep 20, 2010 8:52 am Post subject: |
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| 89shortbox wrote: | | It cant feed any idle fuel cuz the idle mixture screw isnt drilled in the rear metering block. |
why not? ...it pulls the idle fuel from the rear metering block, through the channel in the base plate, to the front idle port.....this gets the fuel flowing and keeps the transfer slot wet with fuel.
without the slight flow the transfer slot would be dry....and not flow. |
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89shortbox
Joined: 04 Nov 2007
Posts: 153
Location: Michigan
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| Posted: Mon Sep 20, 2010 6:48 pm Post subject: |
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NO! Thats why nothing makes sense. The metering block in the rear doesnt have the tapered seat or even a passage drilled in it to allow fuel to flow from the idle well to the passage in the metering block that lines up with the main body to feel the idle port. On all three carbs the t-slot is the only thing that can get fuel off the idle well in the rear.
I can post pics if you like.
_________________
----------------------
89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season. |
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