73 Carb Problem
Thread Starter
8th Gear
Joined: Aug 2012
Posts: 8
Likes: 0
73 Carb Problem
I have a 73 stock 350 vette with a quadrajet (divorced choke). I am a novice with carbs, but on start up it will idle roughly and stall whenever you press the gas. If you just let it sit for about 10 min, the idle will smooth out and it drives like a champ.
I'm assuming something needs to be done about the choke, but wanted to see if anyone has experience with tuning or working on divorced choke quadrajet.
I'm assuming something needs to be done about the choke, but wanted to see if anyone has experience with tuning or working on divorced choke quadrajet.
Drifting
Joined: Jul 2008
Posts: 1,483
Likes: 459
From: Lititz PA
I'm surprised no one has offered some suggestions yet. Posting a picture of your choke setup would help. Even a video with sound would be helpful.
Have you done anything else to the engine as far as a tune-up is concerned? Points, plugs, timing, etc.? Also, I suggest you do a search for "Lars" and you'll find lots of text about setting timing and tuning a carb.
Welcome to the forum!
John
Have you done anything else to the engine as far as a tune-up is concerned? Points, plugs, timing, etc.? Also, I suggest you do a search for "Lars" and you'll find lots of text about setting timing and tuning a carb.
Welcome to the forum!
John
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
Can you post a picture so we can see is everything is hooked up correctly? Is this a new car to you or has the issue just started?
Send an email to Lars, the Qjet guru, V8FastCars@msn.com and ask for his papers on how to set up the carb and choke. He may well chime in when he sees this thread.
Send an email to Lars, the Qjet guru, V8FastCars@msn.com and ask for his papers on how to set up the carb and choke. He may well chime in when he sees this thread.
Tech Contributor
Joined: Aug 1999
Posts: 14,373
Likes: 6,370
From: At my Bar drinking and wrenching in Lafayette Colorado
You may have 2 issues:
1. Incorrect setup and adjustment of the choke system.
2. Inoperative accelerator pump due to ethanol-enhanced fuels.
If your accel pump is inoperative, it will make the engine die when you depress the accelerator when cold, but will often not have great effect on a hot engine.
E-mail me for my Q-Jet Setup Paper and adjust your choke per the procedure in the paper. Then, check your accel pump per the instruction in the paper (under the heading "Quickie Performance Setup) and replace it with the part number recommended if there is an issue.
Lars
V8FastCars@msn.com
1. Incorrect setup and adjustment of the choke system.
2. Inoperative accelerator pump due to ethanol-enhanced fuels.
If your accel pump is inoperative, it will make the engine die when you depress the accelerator when cold, but will often not have great effect on a hot engine.
E-mail me for my Q-Jet Setup Paper and adjust your choke per the procedure in the paper. Then, check your accel pump per the instruction in the paper (under the heading "Quickie Performance Setup) and replace it with the part number recommended if there is an issue.
Lars
V8FastCars@msn.com
Thread Starter
8th Gear
Joined: Aug 2012
Posts: 8
Likes: 0
Tried Something
I just started the engine with the air cleaner off and the primaries were wide open, so I closed them slightly manually and manually pulled throttle. Sounded great and didn't stall, so I'm assuming I need a new choke spring? coil? not really sure what it's called.
Either way the choke isn't pulling the carb shut on start up right? Is its job to get a rich fuel mixture on start up by partially closing and choking off air flow?
Either way the choke isn't pulling the carb shut on start up right? Is its job to get a rich fuel mixture on start up by partially closing and choking off air flow?
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Thread Starter
8th Gear
Joined: Aug 2012
Posts: 8
Likes: 0
No problem, I'm new so it wouldn't surprise me if it were something simple that I was forgetting. My initial thought was that those coiled up metal divorced choke mechanisms (still not sure what they are officially called) go bad over time. Considering how they actually work.
I just want someone with some experience to either reassure me it's not closing the carb properly on start up thus getting my rough start. Or is there something else I'm missing.
I just want someone with some experience to either reassure me it's not closing the carb properly on start up thus getting my rough start. Or is there something else I'm missing.
Drifting
Joined: Jul 2008
Posts: 1,483
Likes: 459
From: Lititz PA
The choke plate mechanism might just be stuck. With the engine off, gently move the choke linkage back and forth, and spray some carb cleaner on everything that moves. Study the linkage and look for something that might be rubbing or binding. Also, while you're doing this, you should see the choke rod that goes into the manifold moving up and down. If you feel the mechanism getting easier to move, then you going in the right direction.
John
John