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#1
09-18-2010, 01:41 PM
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Re: 72 TA : New Project
Steve, my former WW5 HO car would nose over around 4,500...I ended up changing the metering rods and adjusting the secondary air valve. Problem solved.
To start, make sure you have the correct metering rods, hanger and cam. I would start with 3/4 to 1 full turn on the air valve and go from there. I'll see if I can find which rods I used... Mike 
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#2
09-18-2010, 02:22 PM
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Re: 72 TA : New Project
What you describe is exactly it. It seems to run out of gas at that rpm. The secondaries open very smoothly and without any bog or hesitation so hopefully it's a metering rod thing. I don't have much experience in tuning quadrajets. Any recommended websites for info (or local NJ people in the area).
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#3
09-18-2010, 07:26 PM
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Re: 72 TA : New Project
Some info here: http://www.florida4x4.com/tech/quadrajet/ Download the Q-Jet tuning paper...the writer is a little over the top but you'll get the idea.
Checking/adjusting the air valve is pretty simple. I would tighten the spring by a 1/4-1/2 turn and see what kind of change you see/feel. This alone may fix the problem.
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#4
09-18-2010, 08:04 PM
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Re: 72 TA : New Project
Drove her over to my buddy's garage this morning and got some underside shots, since all I have to this date are the ones taken from a creeper 6" underneath the car when it was on jack stands.
     
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#5
09-19-2010, 01:12 AM
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Re: 72 TA : New Project
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 68 Vert</div><div class="ubbcode-body">Steve, my former WW5 HO car would nose over around 4,500...I ended up changing the metering rods and adjusting the secondary air valve. Problem solved.
To start, make sure you have the correct metering rods, hanger and cam. I would start with 3/4 to 1 full turn on the air valve and go from there. I'll see if I can find which rods I used... Mike </div></div> I checked and the metering rods are the stock CR rods. Just out of curiosity, what would the recommended change be from there?
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#6
09-19-2010, 02:23 AM
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Re: 72 TA : New Project
I see what you mean about that article! I never realized Quadrajets were that complex. I'll see what the secondary air valve spring is set at and go slowly from there.
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#7
09-21-2010, 10:45 PM
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Re: 72 TA : New Project
On the advice of Phil at Custom Rebuilt Carburetors, here in New Joysey, who I bought the 7042273 Quadrajet from in 2005, I unbolted it and brought it by his shop where he freshened it up. He ended up putting in a pair of BE secondary metering rods, replacing the leaner stock CR rods and rechecking everything on the flow bench.
No flat spot anymore. A noticeably more linear power band. Runs scary fast now - keeps pulling all the way up the rpm range. Thankfully I have forged connecting rods now. [img]<<GRAEMLIN_URL>>/burnout.gif[/img] Here's Phil's website. Lots of neat stuff vintage stuff there. He has a lot of rare carbs in case anyone is looking for something weird and original. http://customrebuiltcarbs.com/
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