Well that sucked
I spent an hour typing and the pos computer locked up, and lost it all
Anyway no! The mixture screws are for adjusting the warm engine idle only, and only when the fast-idle cam is NOT engaged.
And the fuel level has to be set first.
And the timing has to be set first, or at least the T-port sync set up.
And the valves need to be properly lashed first.
And the compression needs to be fairly even.
The engine has to be running well when warmed up first, before any choke tuning is tackled.
As to the choke; There are exactly 4 parameters to be adjusted, to tune the choke system, once all the parts are known to be in good working condition.
They are;
1) the closing of the choke blade
2) the vacuum break set by the choke pull-off
3) the fast idle speed on the second highest step
4) the rate of choke blade opening
That's it. that's all you got.
As to #1, the blade has to close all the way, and the colder the ambient, the tighter it should close.
As to #2, the opening has a spec and I'm sorry but I don't remember it. It mighta bin 5/32, measured between the air-horn wall and the edge of the blade with vacuum applied to the device and a slight bit of opening pressure applied to the longer side of the blade.
If the opening is too large 2 things will happen; firstly, the engine will stall almost immediately after starting, but will restart Ok with another rest of the gaspedal, and secondly, at tap-down, the fast idle cam will drop down too far and the engine may struggle to stay running.
If the opening is not large enough two things will happen; Firstly, the engine will stall almost immediately after starting, and will be almost impossible to restart without a clear-flood procedure. Secondly, at tap-down, the fast idle cam may not drop down to the proper step, and the engine will race ,or idle way to fast during the warm up period.
As to #3, this is somewhat arbitrary, but it sets the opening of the transfers, which are your primary fuel delivery system during the warm up period.If the idle speed is too slow, the engine will sputter and perhaps stall. If the speed is too fast, it may flood or puke black smoke.
As to #4), It should take about three minutes to go from full closed to full open on a running engine. The time will vary with the ambient temp.; the colder it is the longer it may take.
An engine warming up on the edge of flooding will take longer to warm up, and it might seem that the choke is not staying on long enough. This is wrong; lean it out.How? Lower the fast idle speed to close up the transfers.But then it wants to stall? Well probably she wants more air; check your PCV system. They like to freeze up in high-humidity areas, or in situations where the car never properly warms up, like short trips. Or check for Icing. Or she may want more timing.This goes back to the beginning. Check the T-port sync first.This may require the timing to be something different than the factory specs.
BTW, the stock slanty should idle around 500 in Drive.And 50 to 100 more in Neutral. 900 in N;something is messed up a lot. 700 is messed up quite a bit. 600 might be OK. Figure out why yours won't go there(start with a vacuum reading, and analysis) ,before you do anything else.
The things to look for have already been mentioned, but here's a recap in the order I would look for them;1)wrong fuel level, 2)Faulty EGR, 3)VALVE LASH, 4)T-Port syc/timing, 5)faulty PCV system, 6)leaking brake booster or plumbing, 7)Leaking HVAC system, 8)Intake manifold Vacuum leaks, 9)uneven or low compression, 10)faulty plug-gaps, 11)convertor, 12)cam-timing.
Like I said, you cannot properly set the choke system until the fully-warm tune is known to be right, and a 900idle (post #30) on a stock slanty is not right.
