Quadrajet metering rods - Team Camaro Tech
Engine General Engine Discussion.

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 24 (permalink) Old Jan 26th, 09, 07:33 PM Thread Starter
Tech Team
Dan
 
Join Date: Dec 2007
Location: Beavercreek, Ohio
Posts: 34
Quadrajet metering rods

I am rebuilding my 68 Quadrajet and after disassembly and cleaning noticed one of the secondary metering rod tips is bent. Is this a big problem? If so, where can I get new ones? The code stamped on them is AX and I'm having a lot of trouble finding them anywhere. Summit has AU,CC,CE,CH,CJ,CK,CL,DA,CP. Could I use one of those? Could I reuse my bent one?

'68 SS/RS 408 BB
"I don't know what the world may need
But a V-8 engine's a good start for me
Think I'll drive and find a place to be surly."
Surly is offline  
Sponsored Links
Advertisement
 
post #2 of 24 (permalink) Old Jan 26th, 09, 08:01 PM
Senior Tech
Paul
 
Join Date: Sep 2001
Location: Queen Creek AZ
Posts: 3,677
Re: Quadrajet metering rods

How bent is it? Like a ninety degree bend or ???

If you lived closer I'd give you some...I have a whole box of QJet parts that I don't use anymore.

Best of 1.55 - [email protected]
paulm is offline  
post #3 of 24 (permalink) Old Jan 26th, 09, 08:12 PM Thread Starter
Tech Team
Dan
 
Join Date: Dec 2007
Location: Beavercreek, Ohio
Posts: 34
Re: Quadrajet metering rods

It's bent like 10 degrees. Maybe 1/32 over the last 3/16 of the tip.

'68 SS/RS 408 BB
"I don't know what the world may need
But a V-8 engine's a good start for me
Think I'll drive and find a place to be surly."
Surly is offline  
 
post #4 of 24 (permalink) Old Jan 26th, 09, 08:36 PM
Senior Tech
Paul
 
Join Date: Sep 2001
Location: Queen Creek AZ
Posts: 3,677
Re: Quadrajet metering rods

Can you just bend it back? The primary rods are thin, they get tweaked every now and then but I would just roll them on a flat surface and straighten them back out...I mean as long as the tip isn't jacked up.

Best of 1.55 - [email protected]
paulm is offline  
post #5 of 24 (permalink) Old Jan 26th, 09, 09:24 PM Thread Starter
Tech Team
Dan
 
Join Date: Dec 2007
Location: Beavercreek, Ohio
Posts: 34
Re: Quadrajet metering rods

This is a secondary rod and can't be bent easily by hand.

'68 SS/RS 408 BB
"I don't know what the world may need
But a V-8 engine's a good start for me
Think I'll drive and find a place to be surly."
Surly is offline  
post #6 of 24 (permalink) Old Jan 27th, 09, 10:03 AM Thread Starter
Tech Team
Dan
 
Join Date: Dec 2007
Location: Beavercreek, Ohio
Posts: 34
Re: Quadrajet metering rods

I found this website: http://www.hioutput.com/tech/qjetrod.html and it looks like AX is the same as CJ and BB. CJ is available from Summit...
Should I use it? What's the difference, anyway?

'68 SS/RS 408 BB
"I don't know what the world may need
But a V-8 engine's a good start for me
Think I'll drive and find a place to be surly."
Surly is offline  
post #7 of 24 (permalink) Old Jan 27th, 09, 10:23 AM
Senior Tech
Paul
 
Join Date: Sep 2001
Location: Queen Creek AZ
Posts: 3,677
Re: Quadrajet metering rods

What's the difference between rods? The taper and the diameter of the tip...it's all about how quickly the metering area changes and the final metering area (the amount of area that the gasoline can flow through...jet diameter - rod diameter).

When the rods are all the way down the fatter part of the rod is in the jet, allowing less space for the gasoline to flow through:

http://www.stratagaz.com/Quadrajet/1...s%20Cruise.jpg

When the rods are further out of the jets the smaller end of the rod is in the jet allowing more gasoline to flow through:

http://www.stratagaz.com/Quadrajet/1...Jets%20WOT.jpg

Best of 1.55 - [email protected]
paulm is offline  
post #8 of 24 (permalink) Old Jan 27th, 09, 10:52 AM
Team Member
 
Join Date: Jun 2000
Location: LaGrange,Il
Posts: 1,026
Re: Quadrajet metering rods

If you cannot straighten the rod and decide to use the CJ rod be sure to change both rods to keep it even.

It will not hurt to try the CJ rod and see if it works. They are super easy to change.

TTFN
Mat

SSCARGO
Mat Klemp is offline  
post #9 of 24 (permalink) Old Jan 27th, 09, 07:37 PM
Senior Tech
Charlie
 
Join Date: May 2007
Location: Baltimore Maryland
Posts: 3,759
Re: Quadrajet metering rods

The rods meter the fuel delivery to the secondaries at a given throttle angle. You have an "AX" on a stock carb? Have you had this since it was new? That seems a little on the rich side for a "stock" carb. The AX rod is what's known as a "L" rod. That means it reaches its rich stage at 70* of the throttle angle. The tip measures .0419" at 70* and tapers down to .0397" at 90* of throttle angle. It starts at .1339" at 0*. 0* is when the secondary throttle plates are opening, but the air valve has not started to open yet. For example, if you push the pedal almost to the floor and the secondaries open to merge in traffic or overtake someone, the air valve isn't opening, but the secondary plates are. What is the main jet and rod combo? In that particular grouping, the AX, CJ and BB all have the same exact metering.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
67CamaroRS/SS is offline  
post #10 of 24 (permalink) Old Jan 28th, 09, 09:41 AM Thread Starter
Tech Team
Dan
 
Join Date: Dec 2007
Location: Beavercreek, Ohio
Posts: 34
Re: Quadrajet metering rods

The main rods are 4B. I got this carb with the engine from a 68 Impala big block when I bought someone's project (He was moving). I've never run the carb in this or any other car. I'm going to make it a daily driver (maybe an occasional trip to the track), so do you have any recommendations for primary/secondary rods?

'68 SS/RS 408 BB
"I don't know what the world may need
But a V-8 engine's a good start for me
Think I'll drive and find a place to be surly."
Surly is offline  
post #11 of 24 (permalink) Old Jan 28th, 09, 10:07 AM
Senior Tech
Paul
 
Join Date: Sep 2001
Location: Queen Creek AZ
Posts: 3,677
Re: Quadrajet metering rods

If you have never even tried the carb, here is a tuning approach:

http://www.corvetteclub.org.uk/files...une_a_qjet.pdf

Best of 1.55 - [email protected]
paulm is offline  
post #12 of 24 (permalink) Old Jan 28th, 09, 11:18 AM
Senior Tech
Charlie
 
Join Date: May 2007
Location: Baltimore Maryland
Posts: 3,759
Re: Quadrajet metering rods

Q-Jets are emissions carbs and are designed to run on the EXACT engine it originally came on, but they can be modified to run on any engine. You are going to have to make some changes to the idle tubes, down channel restrictions, idle mixture screw holes, idle bypass air, main jet, upper and lower air bleeds and primary and secondary rods. I know this sounds like a lot, but these mods are easy to do and once they're done, the carb will out perform ANY carb on the street. I made the switch from an Edelbrock Thunder AVS 650 to a Q-Jet and have never looked back. It delivers more power/torque, better fuel economy and a better idle. The 1st thing people are going to asy is, "ditch the Q-Jet and get a Holley", but IMO, Holley's can't hold a stick to a properly tuned Q-Jet, both in power and MPG.

As far as a rod to suggest, we are going to need to know your specs. Cam size, etc. The carb settings are very specific depending on engine specs. You are going to need a full set of numbered drill bits(1-60 & 61-80).

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
67CamaroRS/SS is offline  
post #13 of 24 (permalink) Old Jan 28th, 09, 11:23 AM
Senior Tech
Paul
 
Join Date: Sep 2001
Location: Queen Creek AZ
Posts: 3,677
Re: Quadrajet metering rods

In addition to what's already been posted...you are going to have make sure that QJet is "Tip top" before you go changing stuff. If there are any issues with it you will lose your mind trying to dial it in.

Best of 1.55 - [email protected]
paulm is offline  
post #14 of 24 (permalink) Old Jan 28th, 09, 11:25 AM
Senior Tech
Charlie
 
Join Date: May 2007
Location: Baltimore Maryland
Posts: 3,759
Re: Quadrajet metering rods

Quote:
Originally Posted by paulm View Post
In addition to what's already been posted...you are going to have make sure that QJet is "Tip top" before you go changing stuff. If there are any issues with it you will lose your mind trying to dial it in.

This is a great suggestion. I agree wholeheartidly. I highly suggest you start by rebuilding the carb and then we begin the modifications.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
67CamaroRS/SS is offline  
post #15 of 24 (permalink) Old Jan 28th, 09, 11:28 AM Thread Starter
Tech Team
Dan
 
Join Date: Dec 2007
Location: Beavercreek, Ohio
Posts: 34
Re: Quadrajet metering rods

This is the carb that came with the engine and the numbers on the carb indicate it may be the original. I tore the engine down, had it machined, and rebuilt it myself. The cam is a new one recommended by the engine shop, so would they be a good place to ask about appropriate rods, needles, etc?

'68 SS/RS 408 BB
"I don't know what the world may need
But a V-8 engine's a good start for me
Think I'll drive and find a place to be surly."
Surly is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome