Carburetor questions
Thread Starter
Racer
Joined: Apr 2011
Posts: 471
Likes: 3
Carburetor questions
Hi to all, I've a stock 350ci and I "should" have a QJet on it (the motor itself is a Crate motor from '94), how can I check which type of carburetor I've installed? Thank you for your help!
Race Director
Joined: May 2006
Posts: 18,692
Likes: 2,572
This link has a picture of a Quadrajet
http://forums.corvetteforum.com/c3-t...-question.html
This link has a picture of a type of Holley
http://forums.corvetteforum.com/c3-t...-question.html
This link has a picture of an Edelbrock
http://www.summitracing.com/parts/EDL-1406/
http://forums.corvetteforum.com/c3-t...-question.html
This link has a picture of a type of Holley
http://forums.corvetteforum.com/c3-t...-question.html
This link has a picture of an Edelbrock
http://www.summitracing.com/parts/EDL-1406/
Last edited by MelWff; Oct 11, 2011 at 09:44 AM.
Thread Starter
Racer
Joined: Apr 2011
Posts: 471
Likes: 3
Looking at the pictures I realized I've a Quadrajet!
So, as I've problems from 1500 to 2500 RPM, I was planning to replace it with a new one.
I was thinking about an Edelbrock with electric choke. My question is: is it better a 500 CFM or a 600 CFM for my stock motor? I've calculated the CFM of my motor and 500 should be enough BUT somebody says 600 is better....
So, as I've problems from 1500 to 2500 RPM, I was planning to replace it with a new one.
I was thinking about an Edelbrock with electric choke. My question is: is it better a 500 CFM or a 600 CFM for my stock motor? I've calculated the CFM of my motor and 500 should be enough BUT somebody says 600 is better....
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
Looking at the pictures I realized I've a Quadrajet!
So, as I've problems from 1500 to 2500 RPM, I was planning to replace it with a new one.
I was thinking about an Edelbrock with electric choke. My question is: is it better a 500 CFM or a 600 CFM for my stock motor? I've calculated the CFM of my motor and 500 should be enough BUT somebody says 600 is better....
So, as I've problems from 1500 to 2500 RPM, I was planning to replace it with a new one.
I was thinking about an Edelbrock with electric choke. My question is: is it better a 500 CFM or a 600 CFM for my stock motor? I've calculated the CFM of my motor and 500 should be enough BUT somebody says 600 is better....
Race Director
Joined: Jun 2000
Posts: 10,039
Likes: 669
From: FL
What type of problems? Trying to fix something by just swapping parts is generally expensive and solves nothing.
95% of "carb" problems are really ignition problems.
I expect that a little recurving of the mechanical advance and setting it at 32-34 degrees mechanical all in by 2500 rpm will solve your problem. Most small blocks like 36 degrees of advance but the fast burn heads like a little less.
95% of "carb" problems are really ignition problems.
I expect that a little recurving of the mechanical advance and setting it at 32-34 degrees mechanical all in by 2500 rpm will solve your problem. Most small blocks like 36 degrees of advance but the fast burn heads like a little less.
Race Director
Joined: Apr 1999
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From: CORVETTE 77 385 C.I. TEXAS
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Thread Starter
Racer
Joined: Apr 2011
Posts: 471
Likes: 3
What type of problems? Trying to fix something by just swapping parts is generally expensive and solves nothing.
95% of "carb" problems are really ignition problems.
I expect that a little recurving of the mechanical advance and setting it at 32-34 degrees mechanical all in by 2500 rpm will solve your problem. Most small blocks like 36 degrees of advance but the fast burn heads like a little less.
95% of "carb" problems are really ignition problems.
I expect that a little recurving of the mechanical advance and setting it at 32-34 degrees mechanical all in by 2500 rpm will solve your problem. Most small blocks like 36 degrees of advance but the fast burn heads like a little less.
Thread Starter
Racer
Joined: Apr 2011
Posts: 471
Likes: 3
This is not true, I don't know but it doesn't means I don't want to learn... I want to learn because I like to play with these things.
Race Director
Joined: Jun 2000
Posts: 10,039
Likes: 669
From: FL
What does "not smooth" mean? Is it jerky? Lazy on throttle tip-in? Rough?
BTW, unless the carb has been mangled by a previous owner or mechanic, a rebuild kit is a lot cheaper than a new carb. Of course, that cost a lot less and requires some skills. Also, don't believe the advertising hype, just beacuse they call it a Performer carb, does not mean that it is a high performance part.
Thread Starter
Racer
Joined: Apr 2011
Posts: 471
Likes: 3
This is shotgun maintenance. No diagnosis, just replacing parts.
What does "not smooth" mean? Is it jerky? Lazy on throttle tip-in? Rough?
BTW, unless the carb has been mangled by a previous owner or mechanic, a rebuild kit is a lot cheaper than a new carb. Of course, that cost a lot less and requires some skills. Also, don't believe the advertising hype, just beacuse they call it a Performer carb, does not mean that it is a high performance part.
What does "not smooth" mean? Is it jerky? Lazy on throttle tip-in? Rough?
BTW, unless the carb has been mangled by a previous owner or mechanic, a rebuild kit is a lot cheaper than a new carb. Of course, that cost a lot less and requires some skills. Also, don't believe the advertising hype, just beacuse they call it a Performer carb, does not mean that it is a high performance part.
Last edited by Iron_dog; Oct 13, 2011 at 11:06 AM.
Race Director
Joined: Jul 2001
Posts: 15,892
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Electric chokes don't work any better than the stock OEM mechanical chokes. Fix yours while you're fixing the other issues.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
Get a non-plastic bucket and parts brush, an air compressor (if you are U.S. military, the base auto shop should have one) a gallon of laquer thinner and goggles. Order a carb kit, nitrophyl float and fuel filter. E-mail Lars Grimsrud for his q-jet choke set up proceedure.
Take the carb off the car and disassemble it, seating all adjustments first, counting and recording turns (do NOT take off the butterflies). Soak everything in the bucket full of laquer thinner for a day (cover the bucket and keep it in a well ventilated, non-inhabited area). Use the brush to remove any visible residue. Put on the goggles and blow compressed air through all passages untill completely clean.
Re-assemble substituting the new parts in the kit for the old, putting all adjustments back where they were originally and adjusting the choke per Lars' instructions.
Bolt it back on and you should be good to go 95% of the time. If not, it may be an ignition problem after all, or adjustments may have been "Bubba'd". We can get you through that either way.
God bless, Sensei
Take the carb off the car and disassemble it, seating all adjustments first, counting and recording turns (do NOT take off the butterflies). Soak everything in the bucket full of laquer thinner for a day (cover the bucket and keep it in a well ventilated, non-inhabited area). Use the brush to remove any visible residue. Put on the goggles and blow compressed air through all passages untill completely clean.
Re-assemble substituting the new parts in the kit for the old, putting all adjustments back where they were originally and adjusting the choke per Lars' instructions.
Bolt it back on and you should be good to go 95% of the time. If not, it may be an ignition problem after all, or adjustments may have been "Bubba'd". We can get you through that either way.
God bless, Sensei
Thread Starter
Racer
Joined: Apr 2011
Posts: 471
Likes: 3
Get a non-plastic bucket and parts brush, an air compressor (if you are U.S. military, the base auto shop should have one) a gallon of laquer thinner and goggles. Order a carb kit, nitrophyl float and fuel filter. E-mail Lars Grimsrud for his q-jet choke set up proceedure.
Take the carb off the car and disassemble it, seating all adjustments first, counting and recording turns (do NOT take off the butterflies). Soak everything in the bucket full of laquer thinner for a day (cover the bucket and keep it in a well ventilated, non-inhabited area). Use the brush to remove any visible residue. Put on the goggles and blow compressed air through all passages untill completely clean.
Re-assemble substituting the new parts in the kit for the old, putting all adjustments back where they were originally and adjusting the choke per Lars' instructions.
Bolt it back on and you should be good to go 95% of the time. If not, it may be an ignition problem after all, or adjustments may have been "Bubba'd". We can get you through that either way.
God bless, Sensei
Take the carb off the car and disassemble it, seating all adjustments first, counting and recording turns (do NOT take off the butterflies). Soak everything in the bucket full of laquer thinner for a day (cover the bucket and keep it in a well ventilated, non-inhabited area). Use the brush to remove any visible residue. Put on the goggles and blow compressed air through all passages untill completely clean.
Re-assemble substituting the new parts in the kit for the old, putting all adjustments back where they were originally and adjusting the choke per Lars' instructions.
Bolt it back on and you should be good to go 95% of the time. If not, it may be an ignition problem after all, or adjustments may have been "Bubba'd". We can get you through that either way.
God bless, Sensei
Melting Slicks
Joined: Mar 2008
Posts: 2,023
Likes: 6
From: Austin Tx
The April 2010 edition of 'Corvette Fever' had a tech article called 'Servicing the Rochester Quadrajet Carburetor'. It has lots of pictures. I can scan it, and email it to you if you want.
Also, another thing I found useful the first time I rebuilt my quadrajet, I bought an old quadrajet of the same style to use as a reference. That was a good thing too. When I went to put my carb back together, I couldn't see how the fast idle, and choke linkage went back together. Having a second carb as a reference helped figure that out. Then you can rebuild the old one, and have a spare carb.
Also, another thing I found useful the first time I rebuilt my quadrajet, I bought an old quadrajet of the same style to use as a reference. That was a good thing too. When I went to put my carb back together, I couldn't see how the fast idle, and choke linkage went back together. Having a second carb as a reference helped figure that out. Then you can rebuild the old one, and have a spare carb.