 D jet air screw adjustment, D jet air screw starting point |
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| SWH |
 Oct 14 2024, 11:27 PM
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#1
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Newbie  Group: Members Posts: 16 Joined: 27-April 24 From: Arizona Member No.: 28,084 Region Association: Southwest Region  |
Just completed engine rebuild on 1974 2.0L. Original D-jet injection system is in place. Did the cam break in this weekend. The throttle body has an air screw that I can’t find any information on where to set. Any information is appreciated in starting point adjustment and how to determine best setting.
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| emerygt350 |
Oct 15 2024, 05:07 AM
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#2
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Advanced Member Group: Members Posts: 3,506 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
Looks great. That screw is really to taste at first. I would suggest you start a full turn or so out, then dial in appropriately to get your 900 idle. However, your idle is going to depend on timing and your ECU idle richness setting. If it is still original cam and displacement, and 0 vacuum leaks you shouldn't have a problem. Set the ECU to the factory notch (normally around 9 o'clock).
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| ctc911ctc |
Oct 15 2024, 08:45 AM
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#3
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Senior Member Group: Members Posts: 1,323 Joined: 9-June 18 From: boston Member No.: 22,206 Region Association: North East States 
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9 Oclock in reference to the direction of the car (front - to - Back) or the direction of the ECU (PassengerSide to DriverSide)? QUOTE(emerygt350 @ Oct 15 2024, 05:07 AM)  Looks great. That screw is really to taste at first. I would suggest you start a full turn or so out, then dial in appropriately to get your 900 idle. However, your idle is going to depend on timing and your ECU idle richness setting. If it is still original cam and displacement, and 0 vacuum leaks you shouldn't have a problem. Set the ECU to the factory notch (normally around 9 o'clock). |
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| emerygt350 |
Oct 15 2024, 09:26 AM
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#4
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Advanced Member Group: Members Posts: 3,506 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
As it would sit in the car and you looking towards the front. So pointed toward the place where the wires come into the ECU. However each is a little different and the factory tune should be marked with a notch.
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| SWH |
Oct 16 2024, 01:50 PM
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#5
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Newbie Group: Members Posts: 16 Joined: 27-April 24 From: Arizona Member No.: 28,084 Region Association: Southwest Region |
Thanks for the feedback. I do have a mild cam from web cam installed, allows for using stock D-jet. Working on car later today will see where you’re recommended setting are at.
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| emerygt350 |
Oct 16 2024, 05:30 PM
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#6
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Advanced Member Group: Members Posts: 3,506 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
Is it a 2056 (bigger jugs and pistons)? Even if not and with the new cam (man I wish I had one), I would be sure to have a cht on plug 3 and an afr gauge. Do you have the tangerine kit on your mps?
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| TheCabinetmaker |
Oct 17 2024, 02:40 PM
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#7
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I drive my car everyday Group: Members Posts: 8,373 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
The air bleed screw sets final idle speed after dwell, timing, and CO are set. It does nothing else.
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| dr914@autoatlanta.com |
Oct 17 2024, 03:00 PM
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#8
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914 Guru Group: Members Posts: 8,232 Joined: 3-January 07 From: atlanta georgia Member No.: 7,418 Region Association: None |
sure does look great, how did you refinish the impellor housing?
set valves dwell and timing, then put the control unit knob in the middle and air bypass two turns out, start the engine let the aux air valve close make sure that you have no vacuum leaks and a good air pressure sensor and a good vacuum advance/retard and that the mechanical advance is working and adjust from there red hot ot 950 rpm QUOTE(SWH @ Oct 14 2024, 10:27 PM) Just completed engine rebuild on 1974 2.0L. Original D-jet injection system is in place. Did the cam break in this weekend. The throttle body has an air screw that I can’t find any information on where to set. Any information is appreciated in starting point adjustment and how to determine best setting. |
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