cold hesitation

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
5,604
113
You asked what I think? I think you should get an Oldsmobile Cutlass. Salon or Supreme. Nice cars either way. :)

Engine type/size...2 or 4 bbl?

Either way, I think your primary choke pulloff (vacuum break) on the passenger front corner of the carb isn't working correctly. That's my guess with all that information that was provided. Put a vacuum pump on it where the hose taps in and see if it pulls in and holds. If it doesn't, then it won't open your choke blade slightly when cold and your car will run rich as all get out until it warms. Or just watch the choke blade once it's set and see if it gets popped open about 1/8" or so when it starts. If it don't, that will tell you too.

Assuming 4 bbl. GM p/n 1706211 if you have the Y 307 V8. If you have the Chebby 305, it's GM p/n 17067800.

 
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RDR89

Apprentice
Thread starter
Jul 25, 2020
69
8
Manassas, VA
You asked what I think? I think you should get an Oldsmobile Cutlass. Salon or Supreme. Nice cars either way. :)

Engine type/size...2 or 4 bbl?

Either way, I think your primary choke pulloff (vacuum break) on the passenger front corner of the carb isn't working correctly. That's my guess with all that information that was provided. Put a vacuum pump on it where the hose taps in and see if it pulls in and holds. If it doesn't, then it won't open your choke blade slightly when cold and your car will run rich as all get out until it warms. Or just watch the choke blade once it's set and see if it gets popped open about 1/8" or so when it starts. If it don't, that will tell you too.

Assuming 4 bbl. GM p/n 1706211 if you have the Y 307 V8. If you have the Chebby 305, it's GM p/n 17067800.

Sorry for the brevity of my original post. Yes it has the Chevy 305. Sure, Cutlass my grandfathers favorite car.
 
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69hurstolds

Geezer
Supporting Member
Jan 2, 2006
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Sorry for the brevity of my original post. Yes it has the Chevy 305. Sure, Cutlass my grandfathers favorite car.
Just yankin' your chain. This morning would be a PERFECT freezing azz morning to see if the choke opens on startup.
What, exactly is it doing when it's cold? Is it chugging, belching black smoke, or...?? There may be something else of concern.

But from the description of it running perfectly fine after warm up tells me that it's likely in the choke system somehow. I believe that is an electric choke. So it seems that part is working.

I gave you the GM part numbers in case you needed to find one for your car and can either get the GM one or an aftermarket equivalent of that number so you know it should fit. Standard has one for the 305 2 or 4 bbl listed under part CPA141 for less than 20 bucks at O'reilly auto parts, and Echlin at Napa has one under CRB 24832 at twice the price, should you find you need one. Around $40 on ebay for an NOS one.
 
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Bonnewagon

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Sep 18, 2009
8,021
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Queens, NY
The choke flap is supposed to open slightly once the engine starts or it can't breathe. Then as it warms it slowly opens all the way. The problem is that they used to measure the initial opening with a drill bit in thousandths, and you can use a vacuum source to open it and adjust. But after '80 or so they went to the actual angle of the flap for the opening measurement. The problem is NO ONE has that tool to measure the angle, probably not even a stealership anymore. All you can do is go by the last years of the inch measurement and adjust after that. Rule of thumb is if the engine dies it is open too much (lean). If it huffs and puffs it is too little (rich). The starting point is between 1/8" and 1/4" but every carb is a bit different so testing and tuning is needed.
 
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69hurstolds

Geezer
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Jan 2, 2006
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Agreed about the angle gage (Kent-Moore J26701...available on ebay for around 80 bucks used). The thing is, if it's 1/8" or 3/16" it won't matter that much in the big picture because 1) you will have air going into engine when cold, and 2) it shouldn't be for too long until the choke starts to open anyway. They specified a choke blade angle because they just wanted to be able to back up the "setting" that your carb should have so the GM tech could say it's set to spec. Even if you used the tool, then if you have to tweak on it to tune it in anyway, then the tool is sort of useless. I'd use the 1/8" drill bit method to start with, then use the screw adjustment to get it where you want it to be. It may take you a bit more time to do it, but I'm sure within 2 or 3 tries you'll have it dialed in where you want it.
 
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