Still problems with the q-jet
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,071
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From: San Diego CA
Still problems with the q-jet
After having a few people look at it, guessing it needs bigger jets. The last mechanic I had look at it said that it seems like the carb is jetted for a 305, hence not getting enough fuel and stumbling. According to Edelbrock the primaries are .073 last time I e-mailed lars he said to go up two sizes. So I'd get .075 jets I assume?
Race Director
Joined: Dec 2004
Posts: 15,022
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I have seen them clogged. Also have seen the pump check ball corroded in place...
Without the car running, look down in the carb and give a slow full stroke of the trhrottle. You should see two solid streams of fuel for the entire stroke. If that is the case, your pump is fine.
Without the car running, look down in the carb and give a slow full stroke of the trhrottle. You should see two solid streams of fuel for the entire stroke. If that is the case, your pump is fine.
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,071
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From: San Diego CA
I should probably add that this carburetor is like a year old max and has had very little use prior to about 2 months ago. I'll have to check those nozzles, edelbrock thinks they could be clogged too. However, lars didn't think so because they're generally too large to clog. I replaced the pump and ball like a month ago so there's like no chance that the pump itself is bad. It's something in the pump's working, obviously.
Racer
Joined: May 2005
Posts: 470
Likes: 1
From: Amelia Ohio
Ya know what, SCRAP IT. I have been screwing around with my 79 q jet to no avail. 
Went out today bought new Holley 600 cfm, bolted on no adjusting and runs better than I ever imagined. Its been a lot of years since I've worked on carbs, but around here they are referred to as Quadra-Junk. 
I'm sorry i spent so much time trying to get it to work.
Went out today bought new Holley 600 cfm, bolted on no adjusting and runs better than I ever imagined. Its been a lot of years since I've worked on carbs, but around here they are referred to as Quadra-Junk. I'm sorry i spent so much time trying to get it to work.
Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
Originally Posted by evalu8r
Ya know what, SCRAP IT. I have been screwing around with my 79 q jet to no avail. Went out today bought new Holley 600 cfm, bolted on no adjusting and runs better than I ever imagined. Its been a lot of years since I've worked on carbs, but around here they are referred to as Quadra-Junk. I'm sorry i spent so much time trying to get it to work.
Went out today bought new Holley 600 cfm, bolted on no adjusting and runs better than I ever imagined. Its been a lot of years since I've worked on carbs, but around here they are referred to as Quadra-Junk. I'm sorry i spent so much time trying to get it to work.
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
I'm not scrapping a practically new q-jet from edelbrock 
So I got fed up with tinkering with it myself and took it to the dynoshop and let em have at it. The Corvette Shop couldn't get me in till next tuesday and I need it ready by Saturday. So it cost me $532 to do the "dynojet" which is basically them doing a fancy rebuild of the carburetor and some other little tweaks to it. Apparently they got it working right now and I've gotta go pick it up today. Least now I'll know how much horsepower it has
So I got fed up with tinkering with it myself and took it to the dynoshop and let em have at it. The Corvette Shop couldn't get me in till next tuesday and I need it ready by Saturday. So it cost me $532 to do the "dynojet" which is basically them doing a fancy rebuild of the carburetor and some other little tweaks to it. Apparently they got it working right now and I've gotta go pick it up today. Least now I'll know how much horsepower it has
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Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
Originally Posted by nitronick
Don't think 2 thousnths is really gonna help that much for a stumble.
Thread Starter
Safety Car
Joined: Dec 2004
Posts: 4,071
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From: San Diego CA
They did quite a bit of work to this "new" carburetor.
First off I'll let you all know my '81 is at 181hp and 260 ft-lbs of torque at the wheels right now Much better than stock.
Now for what they did. The day before I took it to the dynoshop I had a simple mechanic tinker with it, aka screw it up more. So here's what it says exactly.
"Found ignition timing was too far advanced causing cross fire at low speeds. Carb was also running too lean. Adjusted ignition timing to 16 deg. Found carb had too small of jets installed, float level was set too low and had wrong power piston spring installed. Choke rod retaining screw and bracket were installed wrong and choke pull off was bad."
Edelbrock and previous owner. Omg it doesn't stumble any more!! Now I can drive up to LA this Saturday without so many problems. My poor bank account, though 
First off I'll let you all know my '81 is at 181hp and 260 ft-lbs of torque at the wheels right now
Much better than stock.Now for what they did. The day before I took it to the dynoshop I had a simple mechanic tinker with it, aka screw it up more. So here's what it says exactly.
"Found ignition timing was too far advanced causing cross fire at low speeds. Carb was also running too lean. Adjusted ignition timing to 16 deg. Found carb had too small of jets installed, float level was set too low and had wrong power piston spring installed. Choke rod retaining screw and bracket were installed wrong and choke pull off was bad."
Edelbrock and previous owner. Omg it doesn't stumble any more!! Now I can drive up to LA this Saturday without so many problems. My poor bank account, though
