Q-j question
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Joined: Jul 2011
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Q-j question
I have a qj off of a 69 327 car, rebuilt and installed on a 68 427 bb car.
My issues are wot pull from a roll - good
Wot pull from 800-1300 rpm- bog, then picks up
I have replaced and checked everything and im just bored with trying to figure it out on my own.
Is there a way to get out the bog without buying a new carb?
Let me know what you think.
Thanks guys!!
My issues are wot pull from a roll - good
Wot pull from 800-1300 rpm- bog, then picks up
I have replaced and checked everything and im just bored with trying to figure it out on my own.
Is there a way to get out the bog without buying a new carb?
Let me know what you think.
Thanks guys!!
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Check accel. pump shot.
The stock Q-J has sec. air spring adj. screw behind the lever to air valve & an Allen lock screw. Loosen Allan lock screw & tighten adj. screw.
Since it is for a 327, a quick check on the jetting is in order. Sec. has a screw at top middle that holds the hanger & sec. rods. Check letter on hanger & 2 letters on rods.
The stock Q-J has sec. air spring adj. screw behind the lever to air valve & an Allen lock screw. Loosen Allan lock screw & tighten adj. screw.
Since it is for a 327, a quick check on the jetting is in order. Sec. has a screw at top middle that holds the hanger & sec. rods. Check letter on hanger & 2 letters on rods.
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accel shot is fine, I've heard that there not change able to make work.
But thats just what i have been told, Do i need parts for this? oh and another thing, i neutral at idle if i hit it pretty hard it dies off too. timing is set perfect dwell and all the advance bla blah works exactly how the engine book i read said
But thats just what i have been told, Do i need parts for this? oh and another thing, i neutral at idle if i hit it pretty hard it dies off too. timing is set perfect dwell and all the advance bla blah works exactly how the engine book i read said
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
No parts needed yet, check those things. You could disconnect the sec. air valve & wire closed to see if that is the bog problem.
FYI The accel. pump rod has holes to adjust.
FYI The accel. pump rod has holes to adjust.
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The rods have BG on them and the hanger has K next to the screw
#33797
Drifting
Joined: Mar 2011
Posts: 1,886
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Very typically, a bog on acceleration is caused by the secondary air valve spring being too loose, and allowing the secondaries to open too soon. Try setting the spring to 3/4 of a turn and see if that improves anything.
There is a fellow named Lars Grumsfeld (I hope I spelled that right) that has a website that lists the specs for many Quadrajet applications, including the jets and rods used in each application.
If you are swapping the carburetor from one engine to another, you will likely have to retune the carb to match. If you are handy, it's not difficult. Find out what was stock for your replacement engine, and install the same jets and rods. That will be a good start.
Good luck to you.
There is a fellow named Lars Grumsfeld (I hope I spelled that right) that has a website that lists the specs for many Quadrajet applications, including the jets and rods used in each application.
If you are swapping the carburetor from one engine to another, you will likely have to retune the carb to match. If you are handy, it's not difficult. Find out what was stock for your replacement engine, and install the same jets and rods. That will be a good start.
Good luck to you.
Drifting
Joined: Dec 2004
Posts: 1,714
Likes: 42
From: Austin Texas
Can you post a pic of the passenger side of the carb? There should be at least one small vacuum canister ther e and linkage to the secondary flaps from the canister. Posting a pic may may help others identify this?
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Race Director
Joined: Apr 1999
Posts: 11,520
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From: CORVETTE 77 385 C.I. TEXAS
Hopefully they did the pri. also which has jets & rods.
You can check the Q-J vac. hose on pass. front.
Melting Slicks
Joined: Sep 2004
Posts: 3,221
Likes: 665
From: Northeast
Air valve spring tension:
http://www.73-87.com/7387garage/drivetrain/myqjet.htm
http://www.thirdgen.org/quadrajet
Chilton & the chassis manuals also explain the procedure. I noticed on the dyno that my valve didnt open at all. Adjusted the tension and made a big difference. Just something to look at. Probably need a mirror to see what you are doing and dont let allen screw come out. Good luck.
Usually you dont have to touch this but it's not your carb so you dont know what the po did. You do have to make sure the choke is operating correctly first.
http://www.73-87.com/7387garage/drivetrain/myqjet.htm
http://www.thirdgen.org/quadrajet
Chilton & the chassis manuals also explain the procedure. I noticed on the dyno that my valve didnt open at all. Adjusted the tension and made a big difference. Just something to look at. Probably need a mirror to see what you are doing and dont let allen screw come out. Good luck.
Usually you dont have to touch this but it's not your carb so you dont know what the po did. You do have to make sure the choke is operating correctly first.
Last edited by BKarol; Oct 26, 2011 at 10:07 AM.
