Year: 1963
Make: Chevy
Model: Chevy II
Engine Size: 194
Refrigerant Type: r12
Ambient Temp: 87
Country of Origin: United States
Finally got my original 1963 AC system running. Just put the compressor belt on added R12 last night.
The rpms are running at around 600 and once the AC is turned on it drops in RPMS to the point that if I hit the accelerator it stalls.
Should I have increased the idle speed at the carb (single barrel rochester) or is there something else to adjust/correct?
Yes
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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
Yes
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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
Don't you have an adjustable solenoid at the carb to override the idle setting when the A/C in ON?
It's a 1963 model, may not be that elaborate. One could be added of course.
I have learned that I have a Carb Airator (Engine Idle Compensator) that is connected to the manifold that is supposed to prevent stalling when the ac is on. I have taken it apart and cleaned it out and reinstalled. Afterward I did adjust the idle and when AC is not on its at 840 rpms at idle in park, and when AC is on it drops to 600 rpm. Seems high for base idle but that part doesnt seem to be doing that good.
Here is a link for a pic of the part
http://s387.photobucket.com/user/msgdesign/media/ac%20system/IMG_3584_zpsf375d09d.jpg.html][IMG]http://i387.photobucket.com/albums/oo320/msgdesign/ac%20system/IMG_3584_zpsf375d09d.jpg
That air leak is an aftermarket work around for hot idle compensation. It has no connection to the A/C system, and will not magically raise your idle when the compressor is on. It is nothing but a thermostatic vacuum leak, and is likely causing the problem to begin with.
I would not want anything like that installed with the brake booster line in any case.
Your tip-in stall points to a lean condition - and a vacuum leak will just make that worse.
Is this an automatic transmission car?
You need to check the ignition timing, and the idle mixture setting. Too lean or not enough advance will make it stall with the added load.
Is the A/C system an aftermarket unit?
B
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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
I have an aftermarket carburetor in my 1988 B2200 truck, and it does not have any idle compensation for AC. Since I live in Arizona, and use the AC 10 months a year, I just set the idle to about 950rpm with AC off, and when the AC is on it drops about 200 rpm, works fine. And that's a 4-cylinder truck, about 85 hp, Sanden 708 compressor, R-12.
A proper AC compensator should be installed so that the solenoid plunger pushes on the throttle arm when the AC is engaged. That's how it was done on factory AC carb cars and trucks. It's a fool-proof method, and many times is adjustable as well, so you get it right where you need it.
Your numbers look pretty good. You kind of got there from the back side, but you are close.
I pulled a 30+ year old book off my shelf & looked:
194 CID I6
550 RPM +/- 25 rpm Curb Idle
8 Degrees BTDC ignition timing
Curb Idle is set in DRIVE, with the A/C ON, Headlamps ON
Ignition Timing is set at Curb Idle, vacuum advance disconnected & plugged (no vacuum leaks)
Given that you set the timing & mixture in neutral, it may be a bit off - but drive ability trumps a couple of degrees of timing on pre-1965 cars. You may not be able to run the full 8 degrees without pinging on today's gasoline. If it drives ok, record where you are at before you change anything. Small changes from the base tune may help - or not.
Idle fuel mixture in those years was not based on emissions. The book instruction for pre-1965 194's was:
Adjust idle mixture for highest steady vacuum and smoothest idle at Curb Idle RPM. Re adjust Curb Idle if necessary.
B
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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Thanks for looking that up B!
I had tried the 8 degrees previously and got a bit of a bog happening. Usually around 10 to 12 it behaves better.
I may try out a few adjustments after I record where things are.
The next thing I am dealing with is a concern about some potential R12 leakage at the evap. I posted a new thread on it though. Hopefully its a false alarm with the detector I have but something tells me to try and inject some UV dye into the system somehow and look at things after.
Make sure your vacuum advance system works by pulling a vacuum on the distributor diaphragm part, it should not leak and applied vacuum should make it advance. This advance is important for off-idle performance. Without it you have to advance the base timing to make the car able to go anyhere, and then cut the air way back to reduce the idle speed with the timing advanced. That makes it hard to get a consistent idle.
Edited: Mon October 06, 2014 at 5:56 PM by mk378
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