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Choke Adjustment Carter YH Carb
Date: May 22, 2005 06:12PM

I'm just double checking to see if I understand how to adjust the choke on my 63 Spyder. I've reviewed the 63 manual supplement regarding the YH Carb that was linked on an earlier post. I have trouble starting my car cold. I have to use starting fluid each time. After it warms up it will re-start just fine though. I suspect the choke being the problem. I understand that the setting is "1 lean", but my question is how to position the spring itself. Do I "load" the spring under tension which will close the choke plate and then adjust it to "1 lean"? The spring appears to be able to be installed in the housing two different ways. Which is the correct way? The manual doesn't even mention this. I'm sure to you "old pros" this is simple, but I want to make sure I get it right.
Thanks,
John

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Re: Choke Adjustment Carter YH Carb
Posted by: errol ()
Date: May 22, 2005 08:11PM

The spring I think should wind counter clockwise so that if you push the tab on the spring that the outer cover slots in to(This should be toward the bottom of the choke housing if I remember right), clockwise, you are leaning out the choke (opening the butterfly). Pushing the tab on the spring counter clockwise will richen the choke(close the butterfly tighter). After installing the cover, align the notch in the cover 1 mark to the right of the center mark on the choke cover housing. That should 1 mark lean.
Someone will correct me if I am wrong.
Errol

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Re: Choke Adjustment Carter YH Carb
Posted by: John ()
Date: May 22, 2005 09:02PM

I'm with ya on this so far. So, do I engage the spring (choke coil) on the choke coil tang (choke shaft) then continue to turn the housing clockwise until it gets to "1 lean" and therefore completely closing the choke? If so I assume this is done on a cold engine.

If I understand the manual supplement correctly...."When the engine is cold, tension of the thermostat coil spring holds the choke valve closed. When the engine is started, air velocity against the offset-choke valve causes the valve to open slightly against the tension of the thermostatic spring. Vacuum applied to the choke piston also tends to pull the choke valve open."

I'm assuming that the "choke valve" that is mentioned is the choke plate. This leads me to believe that the choke should be closed when cold. On my choke if I engage the spring with the choke coil tang then continue to turn the housing clockwise until I get to "1 lean" I put significant tension on the spring and hold the choke plate closed, what seems to be very tightly. This causes the car to start without the starter fluid but it won't stay running, because the choke plate is still closed (Just a guess).

I hope this better explains my problem. Should I just try a new choke coil? (At $26.00 for NOS, $19.55 for replacement and $9.00 for used, I'd rather try and figure this out and use the one I have.)

Thanks again,
John

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Re: Choke Adjustment Carter YH Carb
Posted by: errol ()
Date: May 22, 2005 09:32PM

You wrote:
"If I understand the manual supplement correctly...."When the engine is cold, tension of the thermostat coil spring holds the choke valve closed. When the engine is started, air velocity against the offset-choke valve causes the valve to open slightly against the tension of the thermostatic spring. Vacuum applied to the choke piston also tends to pull the choke valve open."


That is correct except there is no vacuum on a 63 YH stock. If there is a choke pull off it has been added later I assume. Heat from the base of the turbo is what will release the spring and completely open the choke plate or butterfly.


You wrote:
"I'm assuming that the "choke valve" that is mentioned is the choke plate. This leads me to believe that the choke should be closed when cold. On my choke if I engage the spring with the choke coil tang then continue to turn the housing clockwise until I get to "1 lean" I put significant tension on the spring and hold the choke plate closed, what seems to be very tightly. This causes the car to start without the starter fluid but it won't stay running, because the choke plate is still closed (Just a guess)."


If that is the case, I would assume the spring is on backward and by turning the housing to the right, you are applying more pressure to the plate instead of less. Turning the choke housing clockwise should loosen the pressure on the choke plate or butterfly. Turning it counter clockwise should tighten the tension. The plate or butterfly should be closed but with slight pressure, not really tight (Dependent on the ambient temperature, the colder, the tighter the spring will be). Turning the choke housing counter clockwise should tighten the spring, clockwise should loosen it.


Errol



Edited 3 time(s). Last edit at 05/22/2005 09:41PM by errol.

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Re: Choke Adjustment Carter YH Carb
Posted by: John ()
Date: May 29, 2005 04:01PM

I've tried adjusting the choke housing all sorts of different ways as well as turning the coil anywhich way it will fit. The car still doesn't start cold. Anybody got any other suggestions or sure fire way to adjust the choke?

John

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Re: Choke Adjustment Carter YH Carb
Posted by: errol ()
Date: May 30, 2005 05:27PM

John,
You need to make sure you have enough vacuum to pull the fuel that the carb throttle pump puts out to get to the cylinders. You might try the old way of starting by having someone crank the engine while you hold your hand over the choke side of the carb while cranking. If it starts, remove your hand immediately and see if it keeps running.
If you can't feel a vacuum on your hand while cranking, you have a vacuum leak somewhere or a bad valve train or rings. Possibly the hose from the turbo to the crossover, base of the carb where it mounts to the turbo, or where the crossover mounts to the heads or it could even be in the turbo seal between the vacuum and the exhaust sides.
Be very careful if you try this, and have a fire extinguisher immediately handy in the event it backfires.
Try this at your own risk, as it is not the safest way to start an engine.

This all assumes you have a good carb, which is the first thing I would have checked. Steve Goodman in Golden Co. does a good job in rebuilding them as well as others.



Edited 1 time(s). Last edit at 05/30/2005 05:31PM by errol.

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Re: Choke Adjustment Carter YH Carb
Posted by: Anonymous User ()
Date: May 30, 2005 06:45PM

Do NOT pay attention to the NUMBERED positions...

With engine cold......throttle 1/2 open........turn until the butterfly is within 1/8" of fully closed.....tighten!

Bet it'll start...

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Re: Choke Adjustment Carter YH Carb
Posted by: Dan ()
Date: January 16, 2010 08:32PM

I'm having a little problem interpreting the instructions in my manual about adjusting the choke on my 66 Turbo. If I adjust per the manual, my choke valve is held tightly shut (at 70 degrees ambient temperature). This doesn't seem right. Does anyone have anyting to ad that might help?

Thanks in advance.

GO CARDINALS!!!

Dan
Chandler, AZ
1966 Corsa Turbo Convertible

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Re: Choke Adjustment Carter YH Carb
Posted by: Anonymous User ()
Date: January 16, 2010 09:00PM

Completely closed at 70*F is wrong, mine would always start at that temp with no choke at all. Just pump the throttle 3 times, and it fired right off. I found it's beneficial to have the choke on partially starting at about 50*F, and it's definitely required at 30*F or below. How I set it is I made sure the temp outside is below 30, then I hold open the throttle and turn the choke till it's just barely closed.

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Re: Choke Adjustment Carter YH Carb
Posted by: steve c goodman ()
Date: January 17, 2010 04:47AM

This should be easy to explain but I bet I make a mess of it. The 'tang' on the choke shaft should be captured by the hook of the spring inside the choke cover. This allows you to turn the choke cover CCW until the choke plate is just closed. This is the cold start position. I push gently to open the choke plate and ensure that it springs back to a closed position.

In my way of thinking there isn't that much spring tension against the choke plate when I am finished. I start out with the choke plate open and just rotate the cover until it closes.

Most of the 62-4 YH must have the choke plate closed to start when COLD. At the same time you must have both the choke unloader adjusted as well as the fast idle. If the fast idle is NOT adjusted the engine will be miserable when first started because the choke plate is closed and there isn't enough idle speed to keep it running cleanly. Many times when the engine dies under a full choke condition the plugs are very wet.

Sincere regards, Steve

1962 spyder 3.0L turbo 1967 monza 110/4
1968 monza 110/4 1971 amante gt 110/4

Golden, Colo. CORSA/RMC/PPCC



Edited 1 time(s). Last edit at 01/18/2010 01:23AM by MattNall.

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Re: Choke Adjustment Carter YH Carb
Posted by: steve c goodman ()
Date: January 18, 2010 01:20AM

See I told you all that I would make a mess AND I DID!!!! The rotation is CCW to set the choke as I describe above. I need to read more and type less. I apologize for the error. Makes me mad too, I sat here and worked my hand back and forth to get the rotation correct and still screwed it up. Sorry.

Sincere regards, Steve

1962 spyder 3.0L turbo 1967 monza 110/4
1968 monza 110/4 1971 amante gt 110/4

Golden, Colo. CORSA/RMC/PPCC

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