Quadrajet runs rich
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Clockwise to lean out the idle mixture. But there is a method to achieving a proper idle mixture setting...either by vacuum gauge to achieve the highest vacuum or by a precise tach on the low scale to achieve the highest idle speed.
This adjustment affects the idle mixture, not the main metering to any measureable degree unless it's really out of whack.
If the idle mixture screws don't seem to have an affect on the engine idle or vacuum, then you have a metering issue.
This adjustment affects the idle mixture, not the main metering to any measureable degree unless it's really out of whack.
If the idle mixture screws don't seem to have an affect on the engine idle or vacuum, then you have a metering issue.
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
Originally Posted by gerry72
Clockwise to lean out the idle mixture. But there is a method to achieving a proper idle mixture setting...either by vacuum gauge to achieve the highest vacuum or by a precise tach on the low scale to achieve the highest idle speed.
This adjustment affects the idle mixture, not the main metering to any measureable degree unless it's really out of whack.
If the idle mixture screws don't seem to have an affect on the engine idle or vacuum, then you have a metering issue.
This adjustment affects the idle mixture, not the main metering to any measureable degree unless it's really out of whack.
If the idle mixture screws don't seem to have an affect on the engine idle or vacuum, then you have a metering issue.
and want to underscore that adjusting the screws only affects the idle mixture. If you're thinking that you've got a rich conditions off idle then first check that you're choke is opening completely when warm and that your timing is correct. Too many carb problems are actually timing related.
Thread Starter
Advanced
Joined: Jan 2006
Posts: 58
Likes: 2
i HAVE TO PUT THE CHOKE ON IT TODAY. I purchades a carb from caur USA and they sent me one with a hot air tube type choke. After waiting 3 weeks for the carb, I just accepted the fact that they screwed up. I am going to install the electric chole from my other q jet today at work. It is rich, trust me with no choke on it.
Tell me, when I install the electric choke o this, it there a correct way to set it, then adjust my idle. Any input would help. I won't start working on it to later today, so hopefully I can get some opinions. Thanks
Tell me, when I install the electric choke o this, it there a correct way to set it, then adjust my idle. Any input would help. I won't start working on it to later today, so hopefully I can get some opinions. Thanks
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by Jchrisd
i HAVE TO PUT THE CHOKE ON IT TODAY. I purchades a carb from caur USA and they sent me one with a hot air tube type choke. After waiting 3 weeks for the carb, I just accepted the fact that they screwed up. I am going to install the electric chole from my other q jet today at work. It is rich, trust me with no choke on it.
Tell me, when I install the electric choke o this, it there a correct way to set it, then adjust my idle. Any input would help. I won't start working on it to later today, so hopefully I can get some opinions. Thanks
Tell me, when I install the electric choke o this, it there a correct way to set it, then adjust my idle. Any input would help. I won't start working on it to later today, so hopefully I can get some opinions. Thanks
Does the carb have a Choke blade (the flap that closes over the FRONT part of the carb?
If it does then you can use a thin piece of wire to hold it open for a test.
You have said that it is rich without a choke so getting a choke installed will not help this problem unless the Flap I mentioned is partially or fully closed.
Do you have any way to show us pictures of the carb?
Keep us informed and good luck
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Isn't it amazing how people just disappear without any explaination...much less a thank you..............
People go out of their way to help a member and the wind up without knowing if they were of any help or not..............sad
People go out of their way to help a member and the wind up without knowing if they were of any help or not..............sad
Last edited by Bob Onit; Aug 22, 2006 at 09:00 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Advanced
Joined: Jan 2006
Posts: 58
Likes: 2
I am sorry for not saying thank you. You are correct, I owe you a "I am sorry to all."
I wasn't able to work on the car the last few days, got stuck doing some house work.
Yes the carb has a choke blade. It has an operating choke, but is a hot air choke. What happened is I ordered a rebuilt carb, and requested a 75-78 q-jet with an electric choke, where a hot wire plugs into the side and heats the coil. I got a carb that has a port on the side of the choke (looks like a vacume port) but I believe it is meant for hot air.
Anyway, I removed the 3 screws from my old carb and the electric coil, and installed them on this carb. When I turn the dial, it does in fact work the choke blade, but I wans't sure how to set it up from the start. (Where do you set the position of the blade say when the motor is cold and the key is off??
Again, I am sorry for being rude, and I am glad you brought it to my attention. I some times take things for granted.
I will check back sometime today.
I wasn't able to work on the car the last few days, got stuck doing some house work.
Yes the carb has a choke blade. It has an operating choke, but is a hot air choke. What happened is I ordered a rebuilt carb, and requested a 75-78 q-jet with an electric choke, where a hot wire plugs into the side and heats the coil. I got a carb that has a port on the side of the choke (looks like a vacume port) but I believe it is meant for hot air.
Anyway, I removed the 3 screws from my old carb and the electric coil, and installed them on this carb. When I turn the dial, it does in fact work the choke blade, but I wans't sure how to set it up from the start. (Where do you set the position of the blade say when the motor is cold and the key is off??
Again, I am sorry for being rude, and I am glad you brought it to my attention. I some times take things for granted.
I will check back sometime today.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by Jchrisd
I am sorry for not saying thank you. You are correct, I owe you a "I am sorry to all."
I wasn't able to work on the car the last few days, got stuck doing some house work.
Yes the carb has a choke blade. It has an operating choke, but is a hot air choke. What happened is I ordered a rebuilt carb, and requested a 75-78 q-jet with an electric choke, where a hot wire plugs into the side and heats the coil. I got a carb that has a port on the side of the choke (looks like a vacume port) but I believe it is meant for hot air.
Anyway, I removed the 3 screws from my old carb and the electric coil, and installed them on this carb. When I turn the dial, it does in fact work the choke blade, but I wans't sure how to set it up from the start. (Where do you set the position of the blade say when the motor is cold and the key is off??
Again, I am sorry for being rude, and I am glad you brought it to my attention. I some times take things for granted.
I will check back sometime today.
I wasn't able to work on the car the last few days, got stuck doing some house work.
Yes the carb has a choke blade. It has an operating choke, but is a hot air choke. What happened is I ordered a rebuilt carb, and requested a 75-78 q-jet with an electric choke, where a hot wire plugs into the side and heats the coil. I got a carb that has a port on the side of the choke (looks like a vacume port) but I believe it is meant for hot air.
Anyway, I removed the 3 screws from my old carb and the electric coil, and installed them on this carb. When I turn the dial, it does in fact work the choke blade, but I wans't sure how to set it up from the start. (Where do you set the position of the blade say when the motor is cold and the key is off??
Again, I am sorry for being rude, and I am glad you brought it to my attention. I some times take things for granted.
I will check back sometime today.
I am having a hard time understanding your choke description.....
But if the engine is cold and the key is off the choke should be open about 1/4"
It shouldnt take longer than 90 seconds or so for the choke to open fully with the key in the ON position
Other than the choke issue does the carb perform well?
Last edited by Bob Onit; Aug 22, 2006 at 08:37 AM.
Thread Starter
Advanced
Joined: Jan 2006
Posts: 58
Likes: 2
Yes, it seems to run okay on the highway(haven't reakky driven it very far). But when I pulled into the shop the other day, it was really rich, and everyone noticed it.
I just don't have alot of exp. with the q-jets.
I just don't have alot of exp. with the q-jets.
Safety Car
Joined: Oct 2005
Posts: 3,570
Likes: 1
From: Algonac Michigan
Even though you seem convinced that you have a carb problem,let me state what the Q-Jet Guru(Lars) says over and over "90% of performance issues deal with ignition and not with carburation"
Oh and by the way...Sorry about that
Thing,Just bustin' ***** like Bob said.
Oh and by the way...Sorry about that
Thing,Just bustin' ***** like Bob said.
Thread Starter
Advanced
Joined: Jan 2006
Posts: 58
Likes: 2
No problem. I am not upset...
About the timing.. It is at 10degrees at idle and advances to about 34 total. I tell ya, the car has much more power with the headers and the true duals and the non electric carb and the rv cam and 3.73 gears.( I did that so far, now just tring to get it all working perfectly. I had a holley on it, and it had even more power, but not off the line.
About the timing.. It is at 10degrees at idle and advances to about 34 total. I tell ya, the car has much more power with the headers and the true duals and the non electric carb and the rv cam and 3.73 gears.( I did that so far, now just tring to get it all working perfectly. I had a holley on it, and it had even more power, but not off the line.
Thread Starter
Advanced
Joined: Jan 2006
Posts: 58
Likes: 2
you know what,I can't remember..I will check it again tonight when I get home. I am back and forth at the computer at work, so I can't respond quickly all the time. I am suppose to be doing this short block in a 2001 Lexus es300 (sludge motor). My boss get upset that I spend so much time on the net..Ha HA
I will fill you in later .Thanks.
I will fill you in later .Thanks.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by sly vette
Even though you seem convinced that you have a carb problem,let me state what the Q-Jet Guru(Lars) says over and over "90% of performance issues deal with ignition and not with carburation"
Lars has another paper entitled Q-Jet Problems.
If you read it I believe you would be very surprised what can go wrong commercially rebuilt QJ's... abd the main problem? WAAAAY too rich ad idle even with the idle screws seated all the way in...
It might be on BarryK's site or in the FAQ on this forum.
I have seen it first hand.... usually these carbs are crap.
I bought a reman from a parts store.....It was rebuilt by a company called Champion
It was mounted on my car for about a half hour .... just long enough to figure out it was a POS
Last edited by Bob Onit; Aug 22, 2006 at 07:20 PM.
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Have you tried a new air cleaner? If you hold one up in sunlight you should be able to easily see through all of it...if there's some dark spots or it's gray looking then you need a new one...and yes it will create a very rich condition if you can't see through it at all.