Messed up choke
Thread Starter
4th Gear
Joined: Nov 2017
Posts: 4
Likes: 0
Messed up choke
The car has always run rich when cold. In the Fall i adjusted the choke to be leaner and it seemed, ok, perhaps even too lean, but now that it is very cold it is so rich it wont idle until runabout 10 minutes. Is there another adjustment besides rotating the choke or is there some other factor affecting it? Any help would be appreciated.
Race Director
Joined: May 2006
Posts: 18,626
Likes: 2,553
depending upon where you are the ideal temperature for adustment is 70 degrees at which point the choke should just lightly completely close. You make no mention of what year the car is or whether a Holley or a Quad or something else. Once the car starts most carbs have a choke pulloff mechanism which slighly opens it to prevent running rich. It may need adjusting.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Rotating the choke coil has a effect on how long (or short) the time the choke is on. There is also a vacuum break on the choke butterfly that opens the butterfly a few degrees as soon as the engine starts. It's not unusual for that vacuum break, also called a choke pull-off to fail. Easy test- Pull the vacuum line off, push the link back into the housing, place your finger over the port, and let the link go. If it stays in the retracted position, it's good.
Thread Starter
4th Gear
Joined: Nov 2017
Posts: 4
Likes: 0
Year is 78
The car is a 1978,original quadrajet carb almost certainly not rebuilt. I am the second owner, I've had it for over 15 years and it sat for many before I got it. Choke pull off problem makes sense and I'll check it tomorrow. Thanks much.
Melting Slicks
Joined: May 2011
Posts: 2,753
Likes: 119
From: Springfield Missouri
maybe it is time to rebuild the carb., it might get you better MPG and its operation. If you can not do it, find someone who specializes in carb rebuilding, ask around to fellow corvetters or ask at a corvette club(JMO) who can do it correctly. There some people on the forum that can do it and test on a test engine, but be prepared to pay for their services. I paid over $300 for a refurbishment of my car(done to correct coloring etc. as well as being rebuilt). Best money I ever spent.
