When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a question for the experts. I have a 81 that I have had for about 6 weeks. The car has had the CCC stripped out and a vacuum advance distributor and regular rochester installed. I experience a very low idle when cold and then after a block or two the idle jumps up the 1200-1500 rpm in park. Seems the idle goes up when it gets warm instead of the other way. I have looked for a way to set the idle down and on the drivers side the screw that sits against throttle is all the way out and still has high idle.
On another note, The ECM in the battery compartment is there but unhooked. Both 4 pin connectors under the hood are open as well, The carb does not have any electronics on it. It also has a reman tag on the front top.
Would the timing be out a bit? It doesn't run on when I shut it off at high idle so I didn't think it was timing.
From: At my Bar drinking and wrenching in Lafayette Colorado
Originally Posted by BT1991
The carb has a reman tag on the front top.
There's your problem: The carb is complete junk. If you want a list of everything wrong with that carb, just send me an e-mail request for my "Commercially Rebuilt Q-Jet Problems." Throw it in the trash and find a good, unmolested, rebuildable Q-Jet.
also possible the choke is non-functional and just barely idles until it is warm enough to idle. also possible it is just too rich with the choke closed and barely runs until it starts to open.
Last edited by derekderek; Jul 20, 2021 at 06:23 AM.
Post pics of the choke.....start there. Disconnect it and see how it performs......if there is no improvement, then Lars is correct....your unit is ready for the round file.
The best bet of getting a Q-Jet that will run right and last a long time is finding a solid core either on CL, Ebay, here in the parts section or other listing sites for parts......
You can also give the guys at Allstate carburetor in Long Island a call......they might be able to put something together for you.
I bought five solid Q-Jet cores last year...they are out there. And believe me.....when you get one setup right, it is worth every penny......there are a dozen members here that have a Lars built Q-Jet on their engine and have been on the car for years.......
Only two ways a Q-Jet goes bad......when it sits for a thousand years, or when someone who should be working on it "rebuilds" it.
Lars really isn't kidding. Be sure to ask for his timing and HEI setup papers, too. Following his directions to fix timing could make a huge difference in drivability.
Please post some photos of your setup with the air cleaner assembly removed.
For background, here is the recent saga detailing what it takes to fix a (Chinese) rebuilt Q-Jet. At least the CCC system has already been removed/bypassed!
I talked a guy last year into putting a Q-Jet back on his 72' 350/200 4 speed.....someone had installed the dreaded spread bore to square bore adapter and a Auto Parts Edelbrock 600....it ran like dog ****.
Timing was all wrong too...although it had a whiz bang MSD ready to run unit in it.......
Long story short.....I built a 77' 4 speed Q-Jet for it (pristine core).....converted it to electric choke......and recurved/set timing on the MSD to standard performance spec. The engine was bone stock save for long tube headers and a pair of replacement S/R Torquer heads........it went from 8 MPG and no power through the gears, 200 degree water temp to 16 MPG and it would scratch tires all the way through first gear, 180 degree water temp,......smooth as silk......textbook quality repair. It may seem like its all too much info but all I did was time it and install a good fuel mixer on it......it is that easy once you know.
That is what you are looking for......the 1980 engine is almost identical to the 72'......it will never pull wheel stands but it will get out of its own way, idle and run perfectly with a sorted Q-Jet......
The world has changed a lot in ten years and I can barley keep a carb on the shelf as nobody truly knows how to work on one here in South Texas.....
the diff between a smog era and just before smog era engine is about 1-1/2 points of compression. which is about 6% power output. the rest is timing and fuel mixture and emissions add-ons...
Last edited by derekderek; Jul 20, 2021 at 09:04 AM.
Okay.....so you have no power wire going to the choke coil so it is not functioning and is holding you idle high.......the blue circle is where a keyed 12v power source is supposed to go. The red circles you will loosen with a screwdriver and turn the whole choke coil clockwise, there is a third one at the bottom.....simulating a warm wide open choke condition. The idle should drop afterward.......there is a lever behind the choke coil that holds the throttle open for fast idle during cold start up......
If you have troubles afterward...then the carb needs to be replaced with a good core that is refurbished.
1981 Rochester Question
