Author Topic: 79' TA - idle settings?  (Read 698 times)

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Offline jvmagic

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79' TA - idle settings?
« on: March 20, 2018, 04:03:24 PM »
Hi,

 

After installing the oem rebuilt carb I want to make sure I set the idle speeds correctly. 

403 olds motor (oem)

th350 tranny

Q-Jet carb (rebuilt)

 

What should the car idle at when cold?

 

Idle speed when warm in Park

Idle speed when when in Drive

 

Is it a matter of adjusting the high and low idle screws or is there other adjustments to be made?

 

Thanks in advance.

Offline Stringer

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Re: 79' TA - idle settings?
« Reply #1 on: March 20, 2018, 07:16:02 PM »
Timing = 18 degrees at 1100 RPM
Idle in drive = 550
Idle in park = 900
Idle with A/C = 650

Set the timing with the vacuum advance disconnected. Reconnect the vacuum advance and set the idle screw to the optimal idle. I have never really been able to achieve smooth idle at 550. My car idles more smooth at 750....that puts my idle in park about 1000.

You can then trim out the fuel mixture by using a vacuum gage and adjusting the idle mixture screws to make it run more rich or more lean. Good rule of thum...run the screws all the way in, turn them about 2 turns out and start the adjustment from there. In is more lean - out is more rich. Hook a vacuum gage up to a manifold vacuum port and read the gage. The idea is to adjust the mixture screws until you get the highest point of vacuum.  Mine is about 19 - 19.5 at 750 idle

It is not about adjusting the screws to be exact (although they shouldn't be too far off) it is about fine tuning the fuel and air mixture. Take small 1/8 turns, rev the engine up, let the engine settle, watch the gage adjust some more, etc.  You may need to readjust the idle during the process as well.

Take your time you'll get it.
« Last Edit: March 20, 2018, 07:30:22 PM by Stringer »

Offline Aus78Formula

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Re: 79' TA - idle settings?
« Reply #2 on: March 21, 2018, 02:13:32 AM »
It's all on the radiator support decal if still there, and all based on stock engine that meets stock requirements. Likewise, those RPM settings always seem far too low, a guideline though.

Offline jvmagic

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Re: 79' TA - idle settings?
« Reply #3 on: March 22, 2018, 03:10:15 PM »
It's all on the radiator support decal if still there, and all based on stock engine that meets stock requirements. Likewise, those RPM settings always seem far too low, a guideline though.

Thanks.
The sticker is hard to read.  I'll start with these settings and see how it runs.

Offline Aus78Formula

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Re: 79' TA - idle settings?
« Reply #4 on: March 22, 2018, 08:24:01 PM »
The new stickers are commonly available. Even if you don't replace it, you can see it online for whatever your smog setup is.